Forbidden Archeology: The Hidden History of the Human Race

But even if one were to accept Tobias’s view that the Kanam jaw was neanderthaloid, one would still not expect to discover Neanderthals in the Early Pleistocene, over 1.9 million years ago. Neanderthaloid hominids came into existence at most 400,000 years ago (Bräuer 1984, p. 394) and persisted until about 30,000 or 40,000 years ago, according to most accounts. We note that some workers (Bräuer 1984) confine the Neanderthal line to Eurasia and a small area of North Africa adjacent to Europe. These workers would not expect to find Neanderthals at Kanam in East Africa.

11.2.8 Chemical Testing Of the Kanam And Kanjera Fossils

To ascertain the age of the Kanam jaw and Kanjera skulls, K. P. Oakley of the British Museum performed fluorine, nitrogen, and uranium content tests.

The Kanam jaw and the Kanjera skulls had about the same fluorine content as other bones from the Early and Middle Pleistocene formations where they were found (Oakley 1974, p. 257; 1975, p. 151). But Oakley (1974, p. 257) pointed out that “in volcanic areas (particularly under tropical conditions) fluorine analysis does not provide a reliable method of relative dating.” If this is so, one wonders why he ran the tests. Nevertheless, the results he reported are consistent with the hypothesis that the human bones at Kanam and Kanjera are as old as the faunal remains at those sites. Of course, the agreement in fluorine content might, as Oakley suggested, be the result of uneven fluorine absorption in a volcanic, tropical environment. But then again, it might not.

Oakley (1974, p. 257) found that a Kanjera 4 skull fragment showed just a trace of nitrogen (0.01 percent), while a Kanjera 3 skull fragment showed none. Neither of the two animal fossils tested showed any nitrogen. The presence of “measurable traces” of nitrogen in the Kanjera 4 skull fragment meant, said Oakley (1974, p. 258), that all the human fossils were “considerably younger” than the Kanjeran fauna.

But certain deposits, such as clay, preserve nitrogen, sometimes for millions of years (Appendix 1.1.2). So perhaps the Kanjera 4 fragment was protected from nitrogen loss by clay. In any case, the Kanjera 3 fragment, like the animal samples, had no nitrogen. It is possible that this human bone was younger than the animal bones, and lost its nitrogen fairly quickly. But the test results do not dictate this interpretation—the bones could be the same age.

As shown in Table 11.2, the uranium content values for the Kanjera human fossils (8 – 47 parts per million) overlapped the values for the Kanjeran fauna (26–216 parts per million). This could mean they were of the same age.

But the human bones averaged 22 parts per million while the mammalian fauna averaged 136 parts per million. To Oakley (1974, p. 257), the substantial difference between the averages meant that “the Kanjera hominids, although fossilized (Upper Pleistocene?), are considerably younger than the Kanjeran faunal stage (Middle Pleistocene).” Similar uranium contents results were obtained at Kanam. The Kanam mandible had 4–12 parts per million eU O , while the Kanam fauna had 60–214 parts per million (Oakley 1975, p. 151). “The low radiometric values of the Kanam jaw fragment strongly suggest that it is younger than the Kanam fauna,” said Oakley (1975, p. 151).

While the uranium content values, as reported, are consistent with the Kanjeran and Kanam faunas being older than the human bones, there are reasons for caution. The values reported for the Kanjeran fauna—26, 131, 146, 159, and 216 parts eU3O8 per million—vary widely. The highest value is 8.3 times greater than the lowest, although the bones are supposedly of the same general age. Also, the uranium content of the Kanjera 3 human fossils ranged from 8 to 42 parts per million, differing by a factor of 5 in a single individual. The high and low values for the Kanam fauna vary by a factor of 3.5, and for the Kanam jaw itself by a factor of 3. This reinforces our observation (Appendix 1.2.4) that the rate at which a bone absorbs uranium depends on many highly variable conditions— such as the concentration of uranium in the groundwater, the rate of groundwater flow, and the nature of the surrounding sediment. Also, different kinds of bone (and, apparently, even different parts of the same bone) may absorb uranium at greatly different rates. All of this tends to reduce the value of uranium content as a relative age indicator.

Oakley himself pointed out: “the distribution of uranyl ions in ground-water, like that of fluorine ions is subject to very considerable variation from place to place . . . it appears that fossil bones of Upper Pleistocene or early Holocene age in Kugata near Mount Homa [close to Kanam] not only contain more fluorine than bones of Lower Pleistocene age at Kanam, but are more radioactive on account of adsorbed uranium” (Tobias 1968, p. 181).

Leakey reported that some of the Kanjera human skull fragments, now classified Homo sapiens cf. sapiens (Groves 1989, p. 291), were found in situ in the Middle Pleistocene Kanjeran deposits. Oakley (1974, p. 257), however, explained: “When deposits such as the Kanjera beds become waterlogged during the wet season, bones lying on the surface become readily incorporated, so that when subsequently discovered they can easily have the appearance of occurring in situ.” Is this what actually happened? Maybe yes, maybe no.

Oakley had to stretch even further to account for the Kanam jaw. After pointing out that Tobias had said the Kanam jaw was comparable to the Middle Pleistocene Rabat jaw, Oakley (1975, p. 152) said: “I suggest that during some interval in Middle Pleistocene times the jaw lay on a surface littered with fossils weathered out from the Kanam beds and it became embedded with these derived fossils in a block of surface limestone which was eventually down-faulted or trapped in a fissure penetrating the Kanam Beds. This would explain the low uranium content and the high degree of calcification, and at the same time take into account L. S. B. Leakey’s statement in his memoirs . . . that Juma Gitau discovered the Kanam jaw fragment while engaged on extracting a molar of tooth of Deinotherium. As he expressed it to me: ‘the jaw was in the same block as an undoubted Lower Pleistocene fossil.’”

Oakley had no trouble inventing special geological scenarios to explain away the stratigraphic evidence. But he offered no proof, such as positive signs of faulting, that these scenarios were correct. Operating as Oakley did, one can easily dispose of any unwanted stratigraphic evidence whatsoever.

But even if we do grant stratigraphic resorting, this does not necessarily show that the hominid fossils at Kanam and Kanjera were younger than the mammalian fossils at these sites. For example, Tobias (1968, p. 181) said: “The low radiometric values of the Kanam mandible do not necessarily bespeak a recent age for the jaw, but only a different history and probably a different age as compared with the other Kanam fauna.” In fact, if the Kanam jaw had been washed in from a Late Pliocene deposit with a low uranium content, it could be older than the Early Pleistocene animal fossils in the Kanam bed.

Tobias, however, chose a more comfortable alternative. “Nothing in these results,” he said “would rule out the possibility that the Kanam mandible was derived from Middle Pleistocene beds in the vicinity, such as those of Rawe close to Kanam West” (Tobias 1968, p. 181). A late Middle Pleistocene date would be favorable for his view that the jaw is neanderthaloid.

Significantly, the uranium content values that Oakley reported in 1974 were apparently not the first he had obtained. In a paper published in 1958, Oakley said, immediately after discussing the uranium content testing of the Kanam jaw: “Applied to the Kanjera bones our tests did not show any discrepancy between the human skulls and the associated fauna” (1958, p. 53). It would appear that Oakley was not satisfied with these early tests and later performed additional tests on the Kanjera bones, obtaining results that were more to his liking.

Our review of the chemical testing of the Kanam and Kanjera fossils leads us to the following conclusions. The fluorine and nitrogen content tests gave results consistent with the human bones being as old as their accompanying faunas. This interpretation can nevertheless be challenged. The uranium content test gave results consistent with the human bones being younger than their accompanying faunas. But here again, if one chooses to challenge this interpretation, one will find ample grounds to do so.

All in all, the results of chemical and radiometric tests do not eliminate the possibility that the Kanam and Kanjera human fossils are contemporary with their accompanying faunas. The Kanjera skulls, said to be anatomically modern (Groves 1989, p. 291), would thus be equivalent in age to Olduvai Bed IV, which is 400,000 to 700,000 years old. The taxonomic status of the Kanam jaw is uncertain. Recent workers hesitate to call it anatomically modern, although this designation cannot be ruled out completely. If it is as old as the Kanam fauna, which is older than Olduvai Gorge Bed I, then the Kanam mandible would be over 1.9 million years old. Also, crude pebble tools were found at Kanam, and more advanced Chellean tools were found at Kanjera.

11.3 The Birth of Australopithecus

In 1924, Josephine Salmons noticed a fossil baboon skull sitting above the fireplace in a friend’s home. Salmons, a student of anatomy at the University of the Witwatersrand in Johannesburg, South Africa, took the specimen to her professor, Dr. Raymond A. Dart. She thus set off a train of events that would win Dart worldwide fame.

The baboon skull given to Dart by Salmons was from a limestone quarry at Buxton, near a town called Taung, about 200 miles southwest of Johannesburg. Upon learning this, Dart asked his friend Dr. R. B. Young, a geologist, to visit the quarry and see what else might be found. At the Buxton quarry, Young found a limestone wall, the surface of which showed signs of old caves, filled in with a hard mixture of sand and travertine (a deposit of calcium carbonate). It was this old cave filling that contained the fossils, including many baboon bones. In fact, baboons still inhabited caves on nearby cliffs. When the sections of the wall containing the ancient cave deposits were blasted, Young collected some fossilbearing chunks and sent them to Dart (Keith 1931, pp. 39– 46).

11.3.1 The Taung Child

Two crates of fossils arrived at Dart’s home on the very day a friend’s wedding was to be held there. Dart’s wife pleaded with him to leave the fossils alone until after the wedding, but Dart opened the crates. In the second crate, Dart saw something that astonished him: “I found the virtually complete cast of the interior of a skull among them. This brain cast was as big as that of a large gorilla” (Wendt 1972, p. 208). Dart then found another piece of rock that appeared to contain the facial bones.

After the wedding guests departed, Dart began the arduous task of detaching the bones from their stony matrix. Without proper instruments, he used his wife’s knitting needles to carefully chip away the stone without damaging the fossil remains. Dart wrote: “No diamond cutter ever worked more lovingly or with such care on a priceless jewel—nor, I am sure, with such inadequate tools. But on the seventy-third day, December 23, the rock parted. I could view the face from the front. . . . The creature which had contained this massive brain was no giant anthropoid such as a gorilla. What emerged was a baby’s face, an infant with a full set of milk teeth and its permanent molars just in the process of erupting. I doubt if there was any parent prouder of his offspring than I was of my Taung baby on that Christmas” (Fisher 1988, p. 27).

After freeing the bones, Dart reconstructed the skull (Figure 11.5). He characterized the Taung baby’s brain as unexpectedly large, about 500 cubic centimeters. The average brain capacity of a large male adult gorilla is only about 600 cubic centimeters. Dart noted the absence of a brow ridge and suggested that the teeth displayed some humanlike features (Boule and Vallois 1957, pp. 87–88). The front teeth were smaller in relation to the back teeth than in the apes, the canines were not as pointed, and there was no diastema. The diastema is a gap between the teeth of the lower jaw in apes. The gap accommodates the tips of the large canines protruding downward from the upper jaw. The teeth of apes tend to be arranged in a U-shaped fashion, with the rows of back teeth on either side of the jaw running straight and parallel to each other. The teeth of the Taung specimen, like those of human beings, were arranged in a curved, parabolic dental arcade. The youthful age of the creature could be determined from the fact that among the 24 teeth, 20 were milk teeth and 4 were permanent molars (Keith 1931, p. 52).

Figure 11.5. Left: The infant Australopithecus skull from a quarry near Taung, South Africa, after a photograph by A. R. Hughes (Day 1989, p. 14). Right: The skull of an immature gorilla, after Eckhardt (1972, p. 95).

Dart also noted that the foramen magnum, the opening for the spinal cord, was set toward the center of the base of the skull, as in human beings, rather than toward the rear, as in adult apes. Dart took this to indicate the creature had walked upright, which meant the Taung specimen was, in his eyes, clearly a human ancestor.

Dart prepared a report for Nature, the prestigious British science journal, and sent it off to England. He also told B. G. Paver, news editor for the Johannesburg Star: “Perhaps I may shortly have news for you that will not be merely a good local lead. I may have something of worldwide significance connected with man’s origin to announce shortly” (Dart 1959, p. 23). Dart gave Paver, who was interested in anthropology, sufficient information to put together an article but made Paver promise not to print it until after his scientific report was published. Nature, however, held Dart’s article for review by other scientists. Paver became impatient and jumped the gun. He published his own story on February 3, 1925. The Nature article appeared four days later (Dart 1959, p. 34). Despite the plan going somewhat awry, Dart’s intuition was correct. He became an overnight celebrity, and letters of praise (and blame) began to pour in.

In his Nature article, Dart reported: “The specimen is of importance because it exhibits an extinct race of apes intermediate between living anthropoids and man” (Wendt 1972, p. 209). From the accompanying fossils, he estimated his find’s age at 1 million years, and called it Australopithecus africanus—the southern ape of Africa. Australopithecus, he believed, was ancestral to all other hominid forms.

Although public interest and adulation flared up quickly, reaction from the scientific community was substantially more reserved. In England, Sir Arthur Keith and Sir Arthur Smith Woodward received the report from Dart with utmost caution.

Sir Arthur Keith’s initial reaction was to give Dart the benefit of the doubt. Keith said: “Professor Dart is not likely to be led astray. If he has thoroughly examined the skull we are prepared to accept his decision” (Johanson and Edey 1981, p. 45). But Keith’s later pronouncements were negative: “one is inclined to place Australopithecus in the same group or sub-family as the chimpanzee and gorilla. . . . It seems to be akin to both” (Nature, Feb. 14, 1924). Some German scientists, such as Hans Weinert, also thought the Taung specimen was nothing more than an anthropoid ape.

The dating of the find also figured into Keith’s disapproval. “The Taung ape is much too late in the scale of time to have any place in man’s ancestry,” he wrote (Johanson and Edey 1981, p. 45). Dart had estimated that the Taung specimen was about 1 million years old. Keith had consistently held that human beings of modern type had existed for well over 100,000 years. But Keith’s ideas about the pace of evolution would not allow a transformation from a creature as apelike as the Taung specimen to modern Homo sapiens in so short a period of time.

Grafton Elliot Smith was even more critical. In his response to Dart’s article in Nature, he noted: “Many of the features cited by Professor Dart as evidence of human affinity, especially the features of the jaw and teeth mentioned by him, are not unknown in the young of the giant anthropoids and even in the adult gibbon” (Dart 1959, p. 36).

As time went by, Smith became increasingly unfavorable. In May 1925, in a lecture delivered at University College, Smith stated, in remarks reported in the Times of London: “It is unfortunate that Dart had no access to skulls of infant chimpanzees, gorillas, or orangs of an age corresponding to that of the Taung skull, for had such material been available he would have realized that the posture and poise of the head, the shape of the jaws, and many details of the nose, face, and cranium upon which he relied for proof of his contention that Australopithecus was nearly akin to man, were essentially identical with the conditions met in the infant gorilla and chimpanzee” (Dart 1959, p. 38).

Grafton Elliot Smith’s critique remains valid even today. As we shall see, despite the enshrinement of Australopithecus as an ancestor of human beings, several scientists remain doubtful. Anatomical features that to some scientists suggest incipient humanity fall for others within the ape family’s range of variation.

The popular press, initially favorable, also began to adopt a different attitude toward Australopithecus, making Dart’s baby, as it came to be called, a subject of jokes and ridicule. A popular journal, The Spectator, asked readers to submit epitaphs for Australopithecus. One entry selected for publication read (Dart 1959, p. 38):

Here lies a man, who was an ape.

Nature, grown weary of his shape,

Conceived and carried out the plan

By which the ape is now the man.

Dart also received trouble from another quarter—Biblical creationists angry with him for proposing the forbidden missing link between ape and man. Dart (1959, p. 40) wrote: “Letters from religious people all over the world poured into my office, warning me that I was ‘sitting on the brink of the eternal abyss of flame’ and would later ‘roast in the general fires of Hell.’”

In 1931, Dart was invited to London to give a report about his Australopithecus find before the Zoological Society of London. At the same meeting, Davidson Black gave his report introducing Beijing man. Black’s presentation was consummately professional, delivered confidently with well-prepared visual aids. Dart, Taung fossil in hand, apparently stumbled through a weak presentation, simply restating his old case, first made in 1924. He failed to change any minds (Dart 1959, pp. 57–58). Dart later submitted a lengthy monograph on Australopithecus to the Royal Society, which refused to publish the work in full. Dart therefore withdrew it.

11.3.2 Dart Retreats

Dart was dismayed by the cool reception he received from the British scientific establishment. “Perhaps like Davidson Black,” he said, “I should have traveled overseas with my specimens to evoke support for my beliefs” (Dart 1959, p. 51). Instead, Dart remained quietly in South Africa, teaching comparative anatomy at the University of the Witwatersrand in Johannesburg. For many years, he stopped hunting for fossils.

British scientists, led by Sir Arthur Keith, maintained their opposition to Dart’s Australopithecus throughout the 1930s. Keith (1931, p. 82) said that he found the brain markings on the endocranial cast of the Taung specimen to be like those of the gorilla or chimpanzee, and not at all human. He recognized some differences between the brain of the Taung specimen and apes but concluded that “the difference is not such as to lead us to separate Australopithecus from the category of anthropoid apes and place it in a separate group—one intermediate to the highest ape and lowest form of humanity” (Keith 1931, p. 86).

The facial skeleton also appeared quite apelike to Keith. He wrote: “Our comparison of the profile and full-face of the Taung specimen with corresponding views of human and anthropoid skulls leaves no doubt as to the true status of Australopithecus, viz. that in all its essential characters it is a true anthropoid ape” (Keith 1931, p. 103).

Here Piltdown man, believed to be similar in geological age to the Taung specimen, entered Keith’s calculations. The skull of Piltdown man, as we saw in Chapter 10, was like that of Homo sapiens. This fact argued against Australopithecus, with its apelike skull, being in the line of human ancestry.

Keith (1931, p. 109) also held that the Taung specimen’s teeth, relatively bigger than those of a human child, were apelike.

What about the position of the foramen magnum, the opening through which the spinal cord enters the bottom of the skull? Keith pointed out that Dart had wrongly compared the position of the foramen magnum in the juvenile Taung skull with that of adult human beings and adult chimpanzees.

In adult humans, the foramen magnum is located toward the center of the bottom of the skull. This indicates erect posture. In adult chimpanzees, the foramen magnum is located toward the back of the skull, indicating a quadrupedal posture. The Taung skull’s foramen magnum was located in the adult human position, so Dart thought this was good evidence for erect posture in Australopithecus.

Keith, however, pointed out that Dart should have compared the position of the foramen magnum in the infant Taung specimen with that of an infant chimpanzee instead of that of an adult. The foramen magnum of a baby chimp lies in around the same position as that of either the Taung specimen (Keith 1931, p. 110).

Also, the foramen magnum of a human child is situated more forward than the foramen magnum of the Taung baby or a baby chimp.

That the foramen magnum in the Taung specimen was located near the base of the skull, rather than the rear, did not, therefore, allow scientists to draw any conclusions about the posture of an adult Australopithecus. For that, they required an adult specimen of Australopithecus, complete with lower limbs, and no such specimen had yet been found.

Keith (1931, p. 115) concluded: “A close examination of all the features of the Taung skull—the size and configuration of the brain, the composition of the cranial walls, the features of face, the characters of jaws and teeth and the manner in which the head was hafted to the neck—leave me in no doubt as to the nature of the animal to which the skull formed part; Australopithecus was an anthropoid ape.”

As for the few humanlike characteristics of the specimen, Keith (1931, p. 53) said: “The features wherein Australopithecus departs from living African anthropoids and makes an approach towards man cannot be permitted to outweigh the predominance of its anthropoid affinities.” For Keith, the total evidence ruled out the possibility that Australopithecus was, as most modern paleoanthropologists firmly believe, a human ancestor.

11.3.3 Broom and Australopithecus

When Dart retired from the world stage, his friend Dr. Robert Broom took up the battle to establish Australopithecus as a human ancestor. From the beginning, Broom displayed keen interest in Dart’s discovery. Soon after the Taung baby made his appearance, Broom rushed to Dart’s laboratory. According to Dart (1959, p. 35): “he strode over to the bench on which the skull reposed and dropped on his knees ‘in adoration of our ancestor,’ as he put it.” British science, however, demanded an adult specimen of Australopithecus before it would kneel in adoration. Early in 1936, Broom vowed to find one.

On August 17, 1936, G. W. Barlow, the supervisor of the Sterkfontein limestone quarry, gave Broom a brain cast of an adult australopithecine. Broom (1951, p. 44) later went to the spot where the brain cast had turned up and recovered several skull fragments. From these he reconstructed the skull of Plesianthropus transvaalensis. The deposits in which the fossil was discovered are thought to be between 2.2 and 3.0 million years old (Groves 1989, p. 198).

More discoveries followed, including the lower part of a femur (TM 1513). Broom and G. W. H. Schepers (1946) described this femur as essentially human (Zuckerman 1954, p. 310). W. E. Le Gros Clark, initially skeptical of this description, later admitted that the femur “shows a resemblance to the femur of Homo which is so close as to amount to practical identity.” In 1949, W. L. Straus, Jr. (1949) said that the femur “resembles man and cercopithecid monkey in about equal degree” (Zuckerman 1954, p. 311). But according to a modern worker, the key diagnostic features of the Sterkfontein femur (TM 1513) are distinct from those of cercopithecid monkeys and African apes and are “characteristic of modern Man” (Tardieu 1981, pp. 77–79). Since the TM 1513 femur was found by itself, it is not clear that it belongs to a Plesianthropus individual. It is possible, therefore, that it could belong to a more advanced hominid, perhaps one resembling anatomically modern humans.

On June 8, 1938, Barlow gave Broom a fragment of a palate with a single molar attached. Broom, as usual, paid Barlow for the fossil, but when Broom asked from where it had come, Barlow was evasive. Broom noticed that the matrix was different from that in which the fossils from Sterkfontein were usually embedded. Some days later, he again visited Barlow and this time insisted that he reveal the source of the fossil.

Barlow told Broom that Gert Terblanche, a local schoolboy, had given him the fossil palate. Broom obtained some teeth from Gert, and together they went to the nearby Kromdraai farm, where the boy had gotten the teeth by pounding them from a fossil skull. Broom collected the skull fragments, and Gert also gave Broom a piece of lower jaw and more teeth. After reconstructing the partial skull, Broom saw it was different from the Sterkfontein type. He called the new creature Paranthropus robustus. As the name robustus indicates, this australopithecine hominid had a larger jaw and bigger teeth than Australopithecus africanus, represented by the Taung baby, and the gracile Plesianthropus specimens from Sterkfontein. The Kromdraai site is now considered to be approximately 1.0 to

1.2 million years old (Groves 1989, p. 198), although some have suggested an age of up to 1.8 million years (Tobias 1978, p. 67).

Broom also found at Kromdraai a fragment of humerus (the bone of the upper arm) and a fragment of ulna (one of the bones of the lower arm). He said: “had they been found isolated probably every anatomist in the world would say that they were undoubtedly human” (Broom 1950, p. 57).

In 1947, Le Gros Clark wrote that the humerus fragment from Paranthropus (TM 1517) displayed “a very close resemblance to the humerus of Homo sapiens and none of the distinctive features found in the recent anthropoid apes” (Zuckerman 1954, p. 310).

As might be expected, not everyone accepted this assessment of the TM 1517 humerus. In 1949, Straus said that “it is in general more like the average chimpanzee than like the average man.” But he added that “this probably should not be stressed since it consistently falls within the ranges of variation of both species” ( Zuckerman 1954, p. 311). A subsequent morphometric analysis done by H. M. McHenry (1972, p. 95) puts the TM 1517 humerus from Kromdraai “within the human range.” As we have seen, scientists attribute the TM 1517 humerus to Paranthropus robustus, a robust australopithecine. Significantly, a robust australopithecine humerus from Koobi Fora, Kenya (ER 739), fell outside the human range in McHenry’s study (1972, p. 95). So perhaps the TM 1517 humerus belonged to something other than a robust australopithecine. It is not impossible that the Kromdraai humerus and ulna, like the Sterkfontein femur, belonged to more advanced hominids, perhaps resembling anatomically modern humans.

World War II interrupted Broom’s excavation work in South Africa. During this interval, he began the task of fully describing his Australopithecus discoveries, including Dart’s Taung specimen.

After the war, Broom found another australopithecine skull (St 5) at Sterkfontein (Figure 11.6). Later he discovered further remains of an adult female australopithecine (St 14)—including parts of the pelvis, vertebral column, and legs. Their morphology, along with certain features of the Sterkfontein skulls, demonstrated, in Broom’s opinion, that the australopithecines had walked erect(Zuckerman 1954, p. 310).

Figure 11.6. Left: The skull of a female chimpanzee (after Zuckerman 1954, p. 308). Right: The St 5 Plesianthropus (Australopithecus) transvaalensis skull discovered by Robert Broom at Sterkfontein, South Africa (Broom et al. 1950, plate 1).

11.3.4 Paranthropus and Telanthropus

At Swartkrans, near Sterkfontein, Robert Broom and J. T. Robinson found, beginning in 1947, fossils of a robust australopithecine called Paranthropus crassidens (large-toothed near-man). This creature had large strong teeth and a bony crest on top of the skull. The crest served as the point of attachment for big jaw muscles.

In addition to the fossils of Paranthropus crassidens, Broom and Robinson found the jaw of another kind of hominid in the Swartkrans cave. They attributed the jaw (SK 15), smaller and more humanlike than that of Paranthropus crassidens, to a new hominid called Telanthropus capensis.

Member 1 at Swartkrans, where all of the Paranthropus bones were found, is now said to be 1.2 to 1.4 million years old (Groves 1989, p. 198) or 1.8 million years old (Susman 1988, p. 782). But ages of 2.0 million and 2.6 million years have also been proposed (Tobias 1978, p. 65). Member 2, where the SK 15 Telanthropus mandible was found, is said to be 300,000 to 500,000 years old. Member 2 is said to represent an erosion channel. This makes it hard to tell how old the SK 15 jaw really is. It could have been washed in with other bones in the Middle Pleistocene. Or perhaps it could have been eroded from Early Pleistocene Member 1. In general, dating fossils found in the South African caves is quite difficult. The caves have been periodically filled and refilled over the course of 1 to 2 million years, resulting in an exceedingly confused stratigraphy. Those who have a degree of faith in chemical dating methods may take note that K. P. Oakley tested the fluorine content of the Telanthropus jaw and found it to be the same as the Paranthropus fossils (Broom and Robinson 1952, p. 113).

In 1961, Robinson “sank” the genus Telanthropus and reclassified the Swartkrans jaw as Homo erectus (Brain 1978, p. 140). Broom and Robinson (1952), however, had previously noted several differences between the SK 15 teeth and those of Beijing man and Java man, both of which are now classified as Homo erectus. In terms of these differences, the SK 15 teeth were more like those of modern humans. Broom and Robinson also described other ways in which the SK 15 teeth were similar to those of modern humans. But the lower front part of the jaw was damaged, making it “impossible to be sure whether there was a trace of a chin or not” (Broom and Robinson 1952, p. 110). The affinities of this apparently somewhat humanlike jaw remain a mystery.

Broom and Robinson found another humanlike lower jaw at Swartkrans. This fragmentary mandible (SK 45) came not from an erosion channel but from the main deposit containing the Paranthropus fossils. Broom and Robinson (1952, p. 112) said: “In shape it is more easily matched or approached by many modern Homo jaws than by that of Telanthropus.” Robinson later referred the SK 45 jaw to Telanthropus and then to Homo erectus (Brain 1978, p. 140). But there are reasons, admittedly not unclouded, to consider other possibilities. Emphasizing the ambiguous nature of the Telanthropus fossils, a recent worker (Groves 1989, p. 275) assigned them to an unnamed species of Homo.

11.3.5 Paranthropus a Toolmaker?

In the years 1979–1983, C. K. Brain of the Transvaal Museum recovered fossil bones of 130 hominid individuals, 30 crude bone tools, and some crude stone tools. The newly discovered Swartkrans fossils included a relatively small number of well-preserved hand and foot bones.

Speaking of the 8 hand bones from Member 1 at Swartkrans, Randall L. Susman (1988, p. 783) said they indicated “that the robust australopithecines had much the same morphological potential for refined precision grasping and for tool-behavior as do modern humans.” Susman (1988, pp. 782–783) noted, however, that the hand bones retained an apelike overall morphology.

The bone tools found at Swartkrans, according to Susman (1988, p. 783), have wear patterns indicating they were used for digging. Susman (1988, p. 783) therefore proposed that Australopithecus (Paranthropus) robustus had used stone and bone implements “for vegetable procurement and processing.”

Most workers believe the making of tools is an exclusive trait of the genus Homo, starting with Homo habilis. According to this view, big-jawed Paranthropus, a robust australopithecine unconnected to the Homo line, munched vegetable matter like the modern gorilla, without the aid of tools.

In a New York Times report (1988), Donald C. Johanson, discoverer of Lucy, the most famous representative of Australopithecus afarensis, said about the Swartkrans hand bones: “The big question is, how can we be 100 percent sure these hands are not from a Homo individual.”

Susman admitted that “the attribution of individual fossils to Paranthropus is complicated by the presence of a second hominid taxon (Homo c.f. erectus) at Swartkrans.” But he pointed out: “In Member 1, however, more than 95% of the cranio-dental remains are attributed to Paranthropus. This fact suggests that there is an overwhelming probability that any one specimen recovered from Member 1 samples [represents] Paranthropus” (Susman 1988 p. 782). But even Susman (1988, p. 782) admitted that a thumb metacarpal (SK 84) found in Member 1 at Swartkrans in 1949 probably belonged to a Homo individual rather than Paranthropus.

So any matching of hand bones with hominid species at Swartkrans is still uncertain. The only thing that could end this uncertainty would be the discovery of hand bones in undisputed connection with other Paranthropus fossils.

But even if the new hand bones do belong to Paranthropus, there is no guarantee that Paranthropus, rather than Homo, made any of the stone and bone tools found at Swartkrans. “Did the two species live side by side?” asks anthropologist Eric Delson of the City University of New York. “Did [P. ] robustus use leftovers of Homo erectus tool kits? There is no way to test these questions adequately” (Bower 1988, p. 345).

11.3.6 Makapansgat and Final Victory

In 1925, Raymond A. Dart investigated a tunnel at Makapansgat, South Africa. Noting the presence of blackened bones, Dart (1925) concluded hominids had used fire there. In 1945, Philip V. Tobias, then Dart’s graduate student at the University of the Witwatersrand, found the skull of an extinct baboon in the cave deposits of Makapansgat and called it to Dart’s attention. In 1947, Dart himself went back out into the field, after a lapse of two decades, to hunt for Australopithecus bones at Makapansgat.

At Makapansgat, Dart (1948) found australopithecine skull fragments (including an occipital) and other bones, along with more signs of fire. Dart therefore called the creature who lived there Australopithecus prometheus, after the Titan who stole fire from the gods. Today, Australopithecus prometheus is classified, along with the Taung and Sterkfontein specimens, as Australopithecus africanus, distinct from the robust australopithecines of Kromdraai and Swartkrans.

Most of the Makapansgat fossils came from dumps of broken rock in front of the quarry there. From the matrix surrounding the fossils, Dart said he was able to correlate them with identifiable fossil-bearing strata nearby. Had anatomically modern human fossils been recovered in such fashion, any claims for their great age would have been subjected to merciless criticism. This is because the main hominid layers at Makapansgat have been dated at about 3 million years by paleomagnetic methods (K. Weaver 1985, p. 596).

Dart discovered 42 baboon skulls at Makapansgat, 27 of which had smashed fronts. Seven more showed blows on the left front side (Dart 1959, p. 106). Dart, suspecting that australopithecines had been the cause of the damage, requested that R. H. Mackintosh, a specialist in forensic medicine at the University of the Witwatersrand, examine the skulls. Dart and Mackintosh concluded that the skulls showed signs of having been struck by a “powerful downward, forward, and inward blow, delivered from the rear upon the right parietal bone by a double-headed object” (Wendt 1972, p. 224). They believed the weapon was an antelope’s humerus (the bone of the upper forelimb). The joint of an antelope humerus, noted Dart, exactly fit the double impressions on several broken baboon skulls.

From the evidence he gathered at Makapansgat, Dart created a lurid portrait of Australopithecus prometheus as a killer ape-man, bashing in the heads of baboons with primitive bone tools and cooking their flesh over fires in the Makapansgat cave. While his robust cousins had remained in the forest, peacefully munching vegetables, and becoming extinct, this more advanced hominid had, according to Dart, ventured into the dry savannahs, to survive by his ruthless wits, and begin the long journey to humanity.

Dart said: “Man’s predecessors differed from living apes in being confirmed killers; carnivorous creatures, that seized living quarries by violence, battered them to death, tore apart their broken bodies, dismembered them limb from limb, slaking their ravenous thirst with the hot blood of victims and greedily devouring their writhing flesh” (Johanson and Edey 1981, p. 40).

Dart and Mackintosh also ascertained that australopithecines were killed in the same way as the baboons (Wendt 1972, pp. 226–227). “Australopithecus lived a grim life,” wrote Dart (1959, p. 191). “He ruthlessly killed fellow australopithecines and fed upon them as he would upon any other beast, young or old.”

Today, however, paleoanthropologists characterize Dart’s portrait of Australopithecus as somewhat exaggerated. Johanson and Edey (1981, p. 65) call the vision of the killer ape-man “something of an embarrassment to anthropologists, who honor Dart for his dazzling recognition of the first australopithecine, but shake their heads over this later aberration.”

In addition to antelope bones, Dart collected at Makapansgat many other animal remains that he believed had been used as daggers, choppers, saws, clubs, and so forth. He grouped these into what he called an “osteodontokeratic” industry, comprising tools made from bones, teeth, and horns (Dart 1957). In 1954, C. K. Brain found pebble tools at Makapansgat, 25 feet above the main layers in which the australopithecine fossils were found. One possible conclusion: a hominid more advanced than Australopithecus was the maker of the tools. But Dart (1959, pp. 159–160) pointed out that Australopithecus skeletal fragments were also to be found in the same layer as the pebble tools.

Dart’s views about Australopithecus hunting activity at Makapansgat aroused heavy opposition. Some scientists said that the combination of Australopithecus fossils, mammalian bones, and broken baboon skulls represented not hominid occupation sites but the lairs of hyenas or leopards.

To this Dart (1959, pp. 120–131) replied that hyenas, in particular, do not tend to leave such accumulations of bones in their lairs. However, C. K. Brain replied with a more sophisticated version of the carnivore hypothesis that eventually won the day. “Over a period of years,” wrote Richard Leakey and Roger Lewin (1977, p. 96), “Brain observed that a combination of scavenging habits of local carnivores, and the differential resistance to weathering of various types of bone, produces a bone collection virtually identical to the one Dart found in the cave: the osteodontokeratic culture is apparently no more than the left overs from many leopard and hyena meals!”

Nevertheless, this version does not seem to account for some of the evidence reported by Dart. For example, Dart (1959, p. 166) told of finding a gazelle horn wedged solidly into the core of an antelope femur, clear evidence of an intentional act. Dart also noted that the bones of birds, turtles, and porcupines, not the normal prey of hyenas and leopards, were among those found in the cave.

Concerning the evidence for fire at Makapansgat, some researchers said the black deposits were not ash (Oakley 1954, 1956). Others claimed that although there might be signs of fire, the australopithecines were not the cause of them (Broom 1950, p. 74; Johanson and Edey 1981, p. 69).

But even though Dart’s views were discredited, there was a positive result. According to Herbert Wendt (1972, p. 222), the controversy over the Makapansgat discoveries “brought the australopithecines into the news, and enhanced their status even in the eyes of their original critics.”

Another key event was the publication, in 1946, of a monograph on the australopithecines by Broom and Schepers. The National Academy of Sciences of the United States gave Broom and his coauthor the Daniel Giraud Medal for the most important biological work published in that year.

Sir Arthur Keith wrote in 1947: “When Professor Dart of the University of the Witwatersrand, Johannesburg, announced in Nature the discovery of a juvenile Australopithecus and claimed for it a human kinship, I was one of those who took the point of view that when the adult form was discovered it would prove to be nearer akin to the living African anthropoids—the gorilla and the chimpanzee. Like Professor Le Gros Clark I am now convinced on the evidence submitted by Dr. Robert Broom that Professor Dart was right and I was wrong. The Australopithecinae are in or near the line which culminated in the human form” (Dart 1959, pp. 80–81). At long last, Australopithecus had won recognition in the power centers of British paleoanthropology.

11.3.7 Controversy Continues

With the new status of Australopithecus came a change in perception. Increasingly, the vast majority of scientists began to see Australopithecus as less and less apelike and more and more humanlike. Right up to the present, the place of Australopithecus in the direct line of human descent is taken as an indisputable fact by most paleoanthropologists. Pictures of australopithecines generally show them as essentially human from the neck down. Furthermore, the types of behavior displayed by the australopithecines in these pictures are such that figures of humans could be easily substituted. But even after mainstream English science changed its mind about Australopithecus, some scientists resisted. To these recalcitrant renegades, the undistorted facts continued to reveal a starkly apelike portrait of Australopithecus. According to their view, a picture of an Australopithecus individual should show it hanging by its arms from the branch of a tree rather than walking erect and humanlike on the ground.

The primary dissenter, in the early aftermath of English acceptance of Australopithecus, was Sir Solly Zuckerman, secretary of the Zoological Society of London and later a science adviser to the British government. In a comprehensive study, Zuckerman (1954) found that the teeth, skull, jaws, brain, and limbs of Australopithecus were essentially apelike. He therefore believed that attempts to identify australopithecines as human ancestors were misguided. Today, a new generation of dissident researchers is raising and sustaining the same objections to overly humanlike characterizations of Australopithecus. We shall give detailed attention to their views, and those of Zuckerman, in Section 11.8.

11.4 Leakey and His Luck

After the professional and personal disappointments he encountered in the late 1930s, Louis Leakey continued his work in East Africa, assisted by his second wife, Mary. They searched for fossils of Early Pleistocene human ancestors, which Leakey believed would be quite different from Australopithecus and Homo erectus. Eventually, the Leakeys would get lucky and make a series of important finds. But for decades they had to be content with stone tools.

11.4.1 Zinjanthropus

A site of particular interest was Olduvai Gorge in Tanzania. There the Leakeys found crude pebble choppers in Bed I, said to be 1.7 to 2.0 million years old (Oakley et al. 1977, p. 169). They also found round stones that appeared to have been used as bolas (Section 5.3.2). Leakey even found a bone implement he believed had been used for working leather. The standard image of Early Pleistocene hominids is one of ape-men scavenging carcasses of lion kills, not of protohumans working leather and hunting with bolas.

The stone tools Leakey found at Olduvai were not enough to satisfy him. “The remains of the men themselves still elude us,” he said (Goodman 1983, p. 111). Finally, on July 17, 1959, Mary Leakey came across the shattered skull of a young male hominid in Bed I at site FLK. The skull was designated OH 5.

By one account, Leakey came out, looked at the OH 5 skull, and instead of rejoicing said: “Why, it’s nothing but a goddamned robust australopithecine” (Johanson and Edey 1981, pp. 91–92). “When he saw the teeth he was disappointed since he had hoped we would find a Homo and not an Australopithecus,” said Mary Leakey (Johanson and Edey 1981, p. 92).

Mary Leakey eventually pieced together hundreds of fragments, comprising the facial region and the rear part of the hominid’s braincase. The creature had a saggital crest, a bony ridge running lengthwise along the top of the skull. In this respect, it was very much like Australopithecus robustus. Leakey nevertheless created a new species for OH 5, partly because its teeth were bigger than the South African robustus specimens. Leakey called the new find Zinjanthropus boisei. Zinj is a name for East Africa and boisei refers to Mr. Charles Boise, one of the Leakeys’ early financial backers (Wendt 1972, p. 232).

Along with the skull, the cranial capacity of which was about 530 cc, Leakey (1960a, pp. 1050–1051) found bones of mammals, including antelope and pig: “An extensive and rich living floor . . . has been uncovered. . . . All the larger animal bones have been broken open to obtain the marrow; all jaws and skulls of animals are smashed. A high proportion of the bones represent immature animals. Many more stone tools of the Oldowan culture have also been found.” This assemblage apparently caused Leakey to give up his initial reserve and proudly declare to the world that he had found the remains of the first stone tool maker, and hence the first “true man.”

Why Leakey decided to attribute the tools found at the FLK site to Zinjanthropus is somewhat puzzling. Similar tools had been found along with australopithecine remains at Sterkfontein. But Leakey had then said this proved only that the australopithecines of Sterkfontein “were contemporary with a type of early man who made these stone tools, and that the australopithecines were probably the victims which he killed and ate” (Goodman 1983, p. 113).

The FLK site presented a similar situation, calling for a similar explanation. But in a Nature article on Zinjanthropus Leakey said: “There is no reason whatsoever, in this case, to believe that the skull represents the victim of a cannibalistic feast by some hypothetical more advanced type of man” (Goodman 1983, p. 113).

Leakey became the first superstar that paleoanthropology had seen in a while. Along with Zinjanthropus, Leakey flew from Africa to the University of Chicago late in 1959 to participate in the Darwin Centennial, marking the one hundredth anniversary of the publication of The Origin of Species (Goodman 1983, p. 115).

The National Geographic Society honored Leakey with funds, publication of lavishly illustrated articles, television specials, and worldwide speaking tours. In 1962, the Society awarded him its highest award, the gold Hubbard Medal, for “revolutionizing knowledge of prehistory by unearthing fossils of earliest man . . . in East Africa” (Goodman 1983, p. 117).

The National Geographic Society is somewhat different from the other foundations active in paleoanthropological research, such as the Carnegie and Rockefeller foundations. Its funds did not represent the fortune of a single individual or family. The Society started out small and grew on the strength of individual membership contributions, in exchange for which donors received the Society’s now famous journal.

Alexander Graham Bell did, however, play an instrumental role in getting the National Geographic Society started. Although Bell did not give large sums of money, he hired Gilbert Grosvenor to supervise the publication of the Society’s magazine, and paid his salary from his own pocket for many years. When Grosvenor took over editorial duties in 1899, the magazine of the National Geographic Society was a dry technical journal, intended mainly for specialists in geography. He quickly transformed it into a pictorial magazine with vast popular appeal among the middle and upper classes.

Much of the considerable social influence enjoyed by the National Geographic Society has derived from its carefully cultivated relationships with America’s social and political elites. Its board of trustees has consistently represented a cross section of the aristocracies of money and merit. Gilbert Grosvenor himself, from an old New England family, was a cousin of William Howard Taft, who served as President of the United States and Chief Justice of the Supreme Court. Grosvenor married Alexander Graham Bell’s daughter, and his son Melville Bell Grosvenor followed him into leadership of the National Geographic Society.

Through its Committee for Research and Exploration, the National Geographic Society expends funds for scientific work in geography and related fields. Results are publicized not only through the magazine of the Society but through school bulletins, news releases, lecture series, films, and television specials.

Until the Society backed Louis Leakey, it had not, the record of its grants shows, supported any work directly related to evolution. Since then, however, the National Geographic Society has been one of the most influential forces in educating the general public, at least in the United States, about the story of human evolution. Exactly why the Society suddenly became so active in this field, starting in 1959, is not explained in any of the accounts of its history we have thus far seen. We would welcome information about this.

In the September 1960 issue of National Geographic magazine, Louis Leakey (1960b, p. 433) wrote, in a big photo article about Zinjanthropus: “In some respects this new Stone Age skull more closely resembles that of present day man than it does the skulls of the gorilla or of the South African near-men . . . Zinjanthropus represents a stage of evolution nearer to man as we know him today than to the near-men of South Africa.” The article, provocatively titled “Finding the World’s Earliest Man,” featured an artist’s representation of Zinjanthropus. Notwithstanding his huge jowls and low forehead, Zinjanthropus was depicted as blatantly humanlike—a shameless propaganda move.

But despite an outpouring of publicity, the reign of Zinjanthropus was all too brief. F. Clark Howell said: “It obviously was not a man. It was even less manlike than the least manlike of those two South African types” (Johanson and Edey 1981, p. 92). The two South African types were Australopithecus africanus (from Taung, Sterkfontein, and Makapansgat) and Australopithecus robustus (from Kromdraai and Swartkrans). Robustus was considered the least manlike.

Leakey’s biographer, Sonia Cole (1975, pp. 239–240), wrote: “He must have wished he could have eaten his words. . . . Granted that Louis had to persuade the National Geographic Society that in Zinj he had a likely candidate for ‘the first man’ in order to ensure their continued support—but need he have stuck out his neck quite so far? Even a layman looking at the skull could not be fooled: Zinj, with his gorilla-like crest on the top of the cranium and his low brow, was quite obviously far more like the robust australopithecines of South Africa than he was like modern man—to whom, quite frankly, he bears no resemblance at all.”

11.4.2 Homo Habilis

In 1960, about a year after the discovery of Zinjanthropus, Leakey’s son Jonathan found the skull of another hominid (OH 7) nearby in a slightly lower level of Bed I, judged to be about 2 million years old. In addition to the skull, the OH 7 individual included the bones of a hand. Also in 1960, the bones of a hominid foot (OH 8) were found. In succeeding years, more discoveries followed, mostly teeth and fragments of jaw and skull. The fossil individuals were given colorful nicknames: Johnny’s Child, George, Cindy, and Twiggy. Some of the bones were found in the lower part of Bed II.

Philip Tobias, the South African anatomist, gave the first newly found skull a capacity of 680 cc, far larger than Zinjanthropus at 530 cc, and larger even than the biggest australopithecine skull, at roughly 600 cc. It was, however, around

100 cc less than the smallest Homo erectus skulls (Wendt 1972, pp. 245–246).

Leakey sent the OH 7 hand bones to Dr. John Napier of the Royal Free Hospital in England. The results of Napier’s study were pleasing to Leakey. The bones, said Napier (1962, p. 409), were “strikingly human in one revealing and . . . critical character. The tips of the fingers and thumb were surmounted by broad, stout, flat, nail-bearing terminal phalanges, a condition that, as far as we know, is found only in man.”

The Leakeys sent the OH 8 foot bones to Michael Day for reconstruction. Day, recalling his impressions on completing his work, later said: “My hair stood on end. The foot was completely human” (Cole 1975, p. 253).

Like Zinjanthropus, the fossils of the new creatures were found along with broken animal bones and stone tools, scattered across a so-called living floor.

Some distance away from one of the new sites, but at the same level, a circle of large stones was found. The Leakeys interpreted this as the foundation for a windbreak made of brush, giving rise to speculation that the large-brained Olduvai hominid had made use of base camps.

Louis Leakey decided he had now come upon the real toolmaker of the lower levels of Olduvai, the real first true human. His bigger brain confirmed his status, although it was Darwin himself who had said that “one cannot measure intelligence in cubic centimeters” (Wendt 1972, p. 246). A full report on the new Olduvai hominid was published in 1964 by Louis Leakey, John Napier, and Philip Tobias. In this paper (Leakey et al. 1964), they called the creature Homo habilis. The name, suggested by Raymond Dart, means, “handy man.” The designation Homo signified a close family relation to modern humans. As we shall see, however, many scientists doubted whether the honor was merited.

After the discovery of Homo habilis, Zinjanthropus, no longer the first true human, was demoted to Australopithecus boisei, a somewhat more robust variety of Australopithecus robustus. Both of these robust australopithecines had saggital crests, and are regarded not as human ancestors but as evolutionary offshoots that eventually became extinct.

The whole business of saggital crests complicates matters somewhat. Male gorillas and some male chimpanzees also have saggital crests, whereas the females of these species do not (Fix 1984, p. 32). This leads to the possibility that creatures assigned to different australopithecine species, on the grounds that some have saggital crests and others do not, may simply represent sexual variants within a single species. For example, Mary Leakey (1971, p. 281) said: “The possibility that A. robustus and A. africanus represent the male and female of a single species deserves serious consideration.” If the possibility raised by Mary Leakey were found to be correct, this would mean that generations of experts have been wildly mistaken about the australopithecines.

11.4.3 Leakey’s Views on human evolution

With the discovery at Olduvai Gorge of Homo habilis, a creature contemporary with the early australopithecines but with a bigger brain, Louis Leakey believed he had excellent evidence supporting his view that neither Australopithecus nor Homo erectus were in the direct line of human ancestry (Figure 11.7). He later wrote: “For too long scientists have been confused by earlier theories and in particular by those which derived Homo sapiens from classical forms of Neanderthal man, which in turn was supposed to have been derived from Homo erectus, that in turn was said to have been originated in the Australopithecines. . . . Today the vast amount of evidence that has been accumulated shows us clearly that the stock which was leading to ourselves—as distinct from Homo erectus—was already present some 2 million years ago in East Africa and that, at that time, it was contemporary with Australopithecus. We should therefore expect to find evidence that true Homo, as well as primitive Australopithecus, was already present during the late stages of the Pliocene, about 4 million years ago” (L. Leakey 1971, p. 25).

Figure 11.7. According to Louis Leakey (1960d, pp. 210 – 211; 1971, p. 27), neither Australopithecus nor Homo erectus was ancestral to modern humans. The Neanderthals, said Leakey (1971, p. 27), were probably the result of crossbreeding between Homo erectus and Homo sapiens. Today, the details of human evolution remain a subject of active debate. But most paleoanthropologists favor a progression from one of the australopithecines to Homo habilis, Homo erectus, early Homo sapiens, and then the Neanderthals and modern humans.

Although Leakey was now willing to settle for somewhat primitive Homo habilis as the representative of true humanity in the Early Pleistocene, he had earlier believed that the fully modern human type extended that far back in geological time. As we have seen Leakey initially supported Reck’s anatomically modern skeleton, found in Bed II of Olduvai Gorge (Section 11.1). He also campaigned on behalf of his own finds of sapiens-like human fossils at Kanam and Kanjera (Section 11.2). These finds, all of which Leakey originally thought to be from the Middle and Early Pleistocene, would have been the contemporaries of Australopithecus and Homo erectus. Later, Leakey withdrew his support of a Middle Pleistocene date for Reck’s skeleton when challenged by Boswell, and soon thereafter saw his own finds at Kanam and Kanjera discredited in the eyes of most scientists by the same persistent critic. But in reviewing the controversies over these fossils, we have found, despite some ambiguity, sufficient reason to keep them as evidence for sapiens-like beings in Africa 1–2 million years ago.

In Leakey’s opinion, the major problem with the standard view of human origins was that it resulted in a progression that appeared to violate evolutionary principles. “Australopithecinae or ‘near-men’ show a number of characters which very strongly suggest over-specialization in directions which did not lead towards man,” said Leakey (1960d, p. 184). “The very peculiar flattening of the face, the raising of the eye sockets high above the level of the root of the nose, and the shape of the external orbital angles are among such specializations, as is also the forward position of the root of the cheek-bone process.”

Leakey (1960c, p. 212) also stated: “there are those who still hold that Peking man and Java man should be listed as direct ancestors of Homo sapiens, with Neanderthal and Solo types as intermediate forms, but I cannot support this interpretation, which implies too great a measure of reversal of specialization.” Some of Leakey’s contemporaries assumed the earliest hominids would have features reminiscent of modern apes. According to this view, the path of human evolution, proceeding through the australopithecines and Homo erectus, involves a progressive diminution of these primitive apelike features. According to Leakey (1960d), this idea is incorrect.

Certain features of modern apes, such as large brow ridges, are not primitive, said Leakey, but are instead fairly recent specializations. Proconsul, an Early Miocene African ape thought to be at the very root of the human line, did not have large brow ridges. “There is no trace whatsoever of a ridge of bone over the eyes, separating the brain-case from the face,” wrote Leakey (1960d, p. 175).

Modern humans, with their small brow ridges, according to Leakey, preserve the primitive condition found in the Miocene apes. Australopithecus, Homo erectus, and the Neanderthals, with their large brow ridges, depart, like the modern apes, from this primitive condition. The now-dominant evolutionary progression thus involves an evolutionary reversal that Leakey thought unlikely. Miocene apes with no brow ridges give rise to early hominids with heavy brow ridges, and these hominids in turn give rise to modern humans, with small brow ridges. Furthermore, the Miocene apes like Proconsul have thin skulls, while the australopithecines, Homo erectus, and the Neanderthals have relatively thick skulls. Modern humans have thin skulls, implying another evolutionary reversal.

The advocates of punctuated equilibrium in evolution have a response to Leakey, namely that such reversals can be expected (Stanley 1981, p. 155). One of the great advantages of the punctuated equilibrium theory, which holds that speciation occurs not gradually over long periods of time but in rapid bursts, is that it allows advocates of evolution to easily explain away all kinds of contradictions found in the fossil record.

Apart from size, the physical structure of modern human brow ridges is different from that of other hominids. “The brow-ridge over each eye is made up of two component parts in Homo sapiens ,” wrote Leakey (1960d, p. 164). “One part in each case starts just above the nose and extends sideways and slightly upwards to overlap the second part, which, on either side, starts at the extreme edge to right and left of the eye-socket respectively, and extends inwards and slightly downwards. Thus, above the center of each eye-socket, there is an overlap of the two elements.” In Neanderthal, Homo erectus, and Australopithecus, the large brow ridges are most often composed of a single barlike mass of bone running horizontally over the eye sockets. To Leakey (1960d, p. 165), the presence of such barlike brow ridges “suggested not an ancestral stage in human evolution but a side branch that has become more specialized, in this respect, than any Homo sapiens type.”

In addition to features found in the earliest presumed human ancestors (the Miocene apes such as Proconsul ), modern humans also have, said Leakey, other specializations that distinguish them from Homo erectus and Australopithecus.

For example, the jaw of modern Homo sapiens has a chin eminence, which Leakey (1960d, p. 168) described as a “bony buttress on the front of the middle line of the jaw.” Living apes do not have a true chin eminence, and neither do Homo erectus and Australopithecus.

According to Leakey, the purpose of the chin eminence is to strengthen the front portion of the jaw. In apes this is accomplished by the simian shelf, a ridge of bone running between the two sides of the forward part of the lower jaw. In Neanderthals, Homo erectus, Homo habilis, and Australopithecus, none of which have a simian shelf, the strengthening is accomplished by thickening the entire front portion of the jaw.

In making his case, Leakey also considered the presence of a feature of the facial skeleton called the canine fossa. Leakey (1960d, pp. 165–166) stated: “If we look at the facial region of different types of Homo sapiens we find that . . . there is always present a depression or hollow in the bone beneath each eye, which is called the ‘canine fossa.’. . . In the great apes and in the skulls of human species other than Homo sapiens it is only very rarely seen and is more commonly replaced by a convexity or puffing out of the bone in that region.”

Other anatomical differences between Homo sapiens and its presumed ancestors, as discussed by Leakey (1960d), involved the tympanic plate around the ear hole, the mastoid process, the articulation of the jaw, and the position of the foramen magnum.

Time, said Leakey, was another problem. Not only was Homo habilis contemporary with Australopithecus, thus eliminating the latter, in Leakey’s mind, as a human ancestor—there was also trouble with the supposed transition from Homo erectus to Homo sapiens. Leakey (1971, p. 27) wrote: “The textbooks, on the whole, still suggest that Homo sapiens stems from Homo erectus; this view can no longer be sustained. The time interval between Java and Peking man in Asia, or the Olduvai form of Homo erectus in Tanzania, and the appearance of Homo sapiens over a wide area from Europe and east Africa is far too short.” The later specimens of Homo erectus in Java and China, and in the upper levels of Olduvai Gorge, existed from 200,000 to 500,000 years ago in the Middle Pleistocene. Early Homo sapiens, is said to have appeared 300,000 to 400,000 years ago. In other words, Homo erectus and Homo sapiens were roughly contemporary, and this, to Leakey, seemed to eliminate Homo erectus as a human ancestor, although others might suggest that humans branched from Homo erectus far earlier.

Here we are, of course, restricting ourselves to conventionally accepted fossil evidence. In previous chapters, we have argued that the totality of evidence—including the fully modern human skeleton found in a Pliocene formation at Castenedolo in Italy, the advanced stone artifacts and human skeletal remains found in Eocene formations in the California gold country, and much else—does not support an evolutionary origin of the modern human type. If this is correct, then we should not expect the various hominid finds in Africa and elsewhere to line up neatly in an evolutionary sequence. And they do not.

If Australopithecus, Homo erectus, and the Neanderthals were not human ancestors, then how were they to be explained in terms of evolution? As far as the australopithecines were concerned, Leakey (1960d, p. 180) said it was likely that “they represent a very aberrant and specialized offshoot from the stock which gave rise to man.”

Louis Leakey also had some iconoclastic opinions about the relationships among the various australopithecines. “Textbook views that . . . the robust Australopithecus is . . . a late specialized variant of the so-called gracile one . . . cannot any longer be regarded as valid,” wrote Leakey (1971, p. 27). “A number of examples of the robust Australopithecines have now been found in deposits much older than Olduvai, while side by side with them are specimens that apparently represent ancestors of Homo habilis.” Leakey here seems to be referring to discoveries by his son Richard at sites near Lake Turkana, Kenya. As we shall see (Section 11.6), the dating of these Lake Turkana deposits was controversial. Richard Leakey originally favored an age of 2.9 million years, but he eventually agreed with critics that the deposits were about 2 million years old. Even so, the robust australopithecines fossils from Lake Turkana would be as old as the gracile australopithecine fossils found in South Africa. The elder Leakey therefore thought he had good reason to challenge the widely accepted belief that the robust australopithecines were derived from the gracile ones. Leakey’s proposal was given additional support in 1986, with the discovery of the so-called Black Skull (Section 11.11), which pushed the robust australopithecines back to 2.5 million years ago. Mary Leakey, as we have seen, outdid her husband in boldness—she suggested the robust and gracile australopithecines might be the males and females of the same species.

As for Java man and Peking man, representing Homo erectus, Leakey (1960d, p. 186) also considered them “nothing but various aberrant and over-specialized branches that broke away at different times from the main stock leading to Homo.” Leakey was not alone in his views about Homo erectus. In 1972, J. B. Birdsell, an anthropologist at the University of California at Los Angeles, wrote: “It is very difficult to visualize how any of the known forms of Homo erectus could have evolved into the grade of Homo sapiens. . . . nowhere can it be demonstrated that men of the Homo erectus grade did evolve into modern populations” (Goodman 1983, p. 121). Of course, there are many who would disagree with Leakey and Birdsell.

Some authorities have placed much emphasis on fossils such as Rhodesia man in Africa, Solo man in Java, and the European Neanderthals. These, they say, show clearly an evolutionary transition between Homo erectus and Homo sapiens. But Leakey (1971, p. 27) had another explanation: “Is it not possible that they are all variants of the result of crossbreeding between Homo sapiens and Homo erectus ?” One might object that such crossbreeding would have yielded hybrids that were unable to reproduce. But Leakey pointed out that American bison cross fertilely with ordinary cattle.

So whereas some scientists would have Homo erectus evolving into the Neanderthals, who then give rise to modern Homo sapiens, Leakey would have all three coexisting. And as we have seen (Section 9.2.9), there is substantial evidence from the Chinese Middle Pleistocene that Homo erectus coexisted with varieties of Homo sapiens, including Neanderthals. In fact, there is evidence that erectus-like creatures may exist today in isolated wilderness regions, including China (Chapter 10). There are even reports that they have interbred with humans (Section 10.8). All of this agrees with our proposal that various humanlike and apelike creatures have coexisted in the distant past, just as at present.

11.4.4 Evidence for Bone smashing in the Middle Miocene

During the late 1960s, Louis Leakey made some interesting discoveries at Fort Ternan, Kenya. The fossil-bearing formations at this site are said to be from 12.5 to 14.0 million years old (Butzer 1978, p. 198), which makes them Middle Miocene. After noting that hundreds of relatively undamaged fossil mammal bones had been found at Ft. Ternan, Leakey (1968, p. 528) said: “In striking contrast to this situation, there are in the same deposit, and at the same level, small areas of fossils where the bones have been broken up, and where the damage includes excellent examples of depressed fractures of the types usually associated with ‘a blunt instrument.’. . . We also recovered a peculiar lump of lava exhibiting several battered edges, and with every appearance of having been used to smash bones.” According to Glynn Isaac (1978, p. 229), Leakey believed that the lava was not of the kind found normally in the deposit; therefore it must have been transported to the site. Leakey concluded that an apelike Miocene hominid called Kenyapithecus had used the lava stone to crack bones for marrow. E. L. Simons (1978, pp. 548–549) and others considered Kenyapithecus to be an African variety of the Asian hominid Ramapithecus. Currently, however, scientists do not think the ramapithecines can be classified as hominids (Section 3.9). Because no one (as far as we know) now attributes tool behavior to Miocene apes, we are left wondering what hominid used stones to break bones for marrow at Ft. Ternan over 12.5 million years ago. We do not know, but, as we noted in Chapter 2, modern humans leave similar broken bone assemblages.

11.5 A Tale of Two Humeri

In 1965, Bryan Patterson and W. W. Howells found a surprisingly modern-looking hominid humerus (upper arm bone) at Kanapoi, Kenya. In 1977, French workers found a similar humerus at Gombore, Ethiopia.

11.5.1 The Kanapoi Humerus

The Kanapoi humerus fragment, consisting of the intact lower (or distal) part of the bone, was found on the surface. But B. Patterson and Howells (1967, p. 64) noted: “Color, hardness, and degree of mineralization agree with those of numerous specimens collected in situ in the sediments.” Potassium-argon tests on volcanic materials above the bone-bearing sediments yielded dates of 2.9 and 2.5 million years. Paleomagnetic tests showed the lava displayed reverse polarity. The Matuyama Reverse Epoch began 2.5 million years ago, consistent with the potassium-argon results (B. Patterson and Howells 1967, p. 64).

The Pliocene lake sediments also yielded a fauna earlier than that found in Bed I of Olduvai Gorge. Patterson and Howells said it corresponded to the early Villafranchian of Europe. Another researcher later commented on the faunal remains: “These are comparable to those found at the Mursi site in the Omo River valley, with an age of 4.0 to 4.5 million years” (Senut 1979, p. 113). Patterson accepted this as a reasonable date for the layer from which the humerus was thought to have eroded (Oakley et al. 1977, p. 59).

Could the bone have been intrusive in the deposit? B. Patterson and Howells (1967, p. 64) stated: “The excellent state of preservation—the fragment shows no significant postmortem damage other than the break that separated it from the remainder of the original bone—rules out the possibility of derivation from later deposits that may once have been present in the vicinity of the capping lava.”

B. Patterson and Howells (1967, p. 65) said the Kanapoi humerus was “readily distinguishable . . . from gorilla and orangutan.” They then made detailed “morphological and metrical comparisons” with human beings, chimpanzees, and Australopithecus.

Patterson and Howells measured 7 features on 40 human humeri, 40 chimpanzee humeri, and a cast of the distal humerus of Paranthropus robustus (Kromdraii TM 1517), the only australopithecine distal humerus then available. They concluded: “In these diagnostic measurements Kanapoi Hominoid 1 is strikingly close to the means of the human sample. It is larger than the individual of Paranthropus robustus represented by the corresponding humeral fragment from Kromdraai in each measurement” (B. Patterson and Howells 1967, p. 65). Patterson and Howells (1967, p. 65) added: “Paranthropus emerges from these morphological comparisons as rather less man-like than Kanapoi Hominoid 1.” Further emphasizing the humanlike character of the Kanapoi humerus, they said: “there are individuals in our sample of man on whom measurements . . . of Kanapoi Hominoid I can be duplicated almost exactly” (B. Patterson and Howells 1967, p. 66).

Patterson and Howells would not have dreamed of suggesting that the Kanapoi humerus belonged to an anatomically modern human. Nevertheless, if an anatomically modern human had died at Kanapoi 4.0–4.5 million years ago, he or she might have left a humerus exactly like the one they found.

Further confirmation of the humanlike morphology of the Kanapoi humerus (KNM KP 271) came from anthropologists Henry M. McHenry and Robert S. Corruccini of the University of California. Using multivariate analysis techniques, they compared 16 different measurements of the Kanapoi humerus with those of the humeri of all species of anthropoid apes, three species of monkeys, and two fossil hominids—Kromdraai (TM 1517) and East Rudolf (ER 739). McHenry and Corruccini (1975, p. 227) concluded that “the hominid fossil from Kanapoi resembles Homo sapiens very closely.” Elsewhere in the same study they noted: “The Kanapoi fossil is quite close to Homo, especially the Eskimo sample” (McHenry and Corruccini 1975, p. 235). Amplifying this, they stated that “the Kanapoi humerus is barely distinguishable from modern Homo” and “shows the early emergence of a Homo-like elbow in every subtle detail” (McHenry and Corruccini 1975, p. 240).

In an earlier study, McHenry (1973) wrote: “A humeral fragment has been found at Kanapoi that is almost five million years old yet almost indistinguishable in shape from many modern humeri. Geologically much younger australopithecine humeri at one or two million years are vastly different from those of modern man.” In his Harvard doctoral thesis, McHenry (1972, p. 95) stated that the Kana poi humerus fell “within the human range.” We have employed a simple multivariate analysis technique to evaluate the raw data supplied by McHenry in his thesis. We calculated the 16-dimensional vectors represented by his 16 measurements for each humerus, and took the size of the angles between any two vectors as indicators of the degree of similarity between the two humeri. A smaller angle means a greater similarity. This method, it should be noted, is size-independent. In other words, bones of the same conformation, though being of different size, will show a difference of zero degrees. Confirming McHenry, we found that at 2.75 degrees the Kanapoi humerus vector was closest to Homo sapiens. For comparison, the angle of Kanapoi with chimpanzee was 4.40 degrees. With Australopithecus robustus (Kromdraai TM 1517) the angle was 4.51 degrees, and with Australopithecus boisei ( East Rudolf) it was 4.83 degrees. In other words, the Kanapoi humerus differed from those of the australopithecines.

C. E. Oxnard (1975a, p. 97) agreed with McHenry’s analysis. He stated: “we can confirm clearly that the fossil from Kanapoi is very humanlike.” In his discussion, Oxnard pointed out that the Kanapoi humerus, although 4 million years old, was quite modern in form, while the australopithecine humeri from later periods were much less so. This led Oxnard (1975a, p. 121) to suggest, as did Louis Leakey, that the australopithecines were not in the main line of human evolution. Keeping Australopithecus as a human ancestor would result in a very unlikely progression from the humanlike Kanapoi humerus, to the markedly less humanlike humerus of Australopithecus, and then to one more humanlike again.

Michael A. Day (1978, p. 315) said about the Kanapoi humerus: “it is hard to point to a single anatomical feature or group of features that is not well known in modern man. Functionally it must be nearly identical with the modern human condition.”

A dissenting view may be found in a study by Marc R. Feldesman, of Portland State University in Oregon. From his own multivariate analysis of 15 fossil humeri and humeri of 22 species of monkey and apes, Feldesman (1982a, p. 73) concluded: “The Kanapoi distal humerus (KP 271), far from being more ‘human-like’ than Australopithecus, clearly associates with the hyperrobust Australopithecines from Lake Turkana.” The Lake Turkana specimen closest to KP 271, according to Feldesman, was ER 739, now thought to represent Australopithecus boisei. This is exactly the reverse of McHenry’s conclusion. McHenry found that KP 271 was close to Homo sapiens and distant from ER 739. Because Feldesman did not supply his raw data in his report, we could not evaluate his results.

In our discussion of fossil discoveries in China (Section 9.2.1), we made extensive use of the concept of possible date ranges. That is to say, when confronted with reports giving different ages for certain fossils, we established a range of possibilities that included all likely ages. Here we want to introduce a similar concept—that of possible morphology ranges. Concerning the Kanapoi humerus, we can say, on the basis of the reports we have cited, that its morphology range extends to the modern human end of the spectrum.

11.5.2 The Gombore Humerus

In 1977, French researchers (Chavaillon et al. 1977) reported finding a humanlike humerus at the Gombore site in Ethiopia, about 55 kilometers south of the capital, Addis Ababa.

The Gombore humerus was, however, more recent than the Kanapoi humerus. Noting that stone tools were found near the Gombore humerus, Brigitte Senut (1979, pp. 112 –113) stated: “The stone industry of Gombore IB is like that of the upper part of Bed I and the base of Bed II at Olduvai (Tanzania), which have been dated at 1.7 million years by the potassium-argon method. The same radiometric method applied to basalt at the Ethiopian site gives the layers in which the Oldowan tools were found a date older than 1.5 million years.” The first excavators (Chavaillon et al. 1977, p. 961) also noted: “The site is an Oldowan encampment, with a shelter and organized zones containing different types of tools.”

Senut (1979, p. 111) said, in an English summary of one of her French papers, that the Gombore humerus could, along with the Kanapoi humerus, “be attributed to the genus Homo.” Concerning the Kanapoi humerus, Senut was in agreement with B. Patterson and Howells (1967), McHenry and Corruccini (1975), McHenry (1972, 1973), Oxnard (1975a), and Day (1978), who all thought the Kanapoi humerus to be unlike that of Australopithecus. Senut differed from Feldesman (1982a), who thought the Kanapoi humerus to be like that of Australopithecus boisei (ER 739).

Like Senut (1979), the original discoverers of the Gombore humerus hesitated to designate it as anything more than Homo (Chavaillon et al. 1977). Similarly, Feldesman (1982a, p. 92), who thought the Kanapoi humerus to be like those of australopithecines, said: “The Gombore specimen appears to be closer to Homo than to anything else.” But Chavaillon and his coworkers (1977, p. 962) noted: “in the lateral view, the bone very much resembles Homo sapiens sapiens.” Senut later found other features that were humanlike. “Gombore IB 7594,

which was primitively [first] attributed to the genus Homo (Chavaillon et al. 1977, Senut 1979), cannot be differentiated from a typical modern human,” she wrote (Senut 1981b, p. 91).

So now we seem to have two very ancient and humanlike humeri to add to our list of evidence challenging the currently accepted scenario of human evolution. These are the Kanapoi humerus at 4.0–4.5 million years in Kenya and the Gombore humerus at more than 1.5 million years in Ethiopia. At the very least, the Early Pliocene Kanapoi humerus “could challenge the new phylogenies tending to show that only one genus and one species (Australopithecus afarensis) was living at this date” (Senut 1979, p. 111). The Kanapoi and Gombore humeri also support the nonevolutionary view that human beings of modern type have coexisted with other humanlike and apelike creatures for a very long time.

11.6 Richard, Son of Leakey

Louis Leakey’s son Richard at first avoided fossil hunting, working instead as a safari organizer for clients including the National Geographic Society. Eventually, however, Richard took up the family profession. Although he had no university training, he began to develop his own reputation as a competent paleoanthropologist.

In 1967, Richard Leakey, then just 23 years old, led the Kenya section of an international paleoanthropological expedition to the Omo region of southern Ethiopia. Unhappy at having to turn over fossils he discovered to professional scientists, Leakey suddenly left the Omo site. He flew by helicopter to Koobi Fora, on the crocodile-infested eastern shores of Kenya’s Lake Rudolf, now called Lake Turkana. On his very first walk around Koobi Fora, Leakey found a stone tool and fossil pig jaw. The site was promising, but he needed funding in order to systematically develop it.

In January of 1968, Richard Leakey journeyed to Washington, D.C., where he got a grant of 25,000 dollars from the National Geographic Society’s Committee for Research and Exploration. Returning to Kenya, Leakey set up a permanent camp at Koobi Fora.

That first year saw no major discoveries, but in 1969 Richard and his wife Meave found an australopithecine skull. Over the next few years, fossils of three more Australopithecus individuals turned up (R. Leakey 1973b, p. 820). Also, Glynn Isaac found hundreds of crude stone tools at several Early Pleistocene sites near Koobi Fora (R. Leakey 1973b, p. 820). Australopithecus was not known to have been a toolmaker. So who had made the tools?

11.6.1 Skull Er 1470

In August of 1972, Bernard Ngeneo, a member of Leakey’s team, found at Lake Turkana a shattered skull that appeared to give an answer. Richard’s wife Meave, a zoologist, reconstructed the skull, designated ER 1470. Alan Walker of the University of Nairobi estimated that its cranial capacity was over 810 cc (R. Leakey 1973a, p. 449), bigger than the robust australopithecines. For example, the robust OH 5 Australopithecus boisei specimen from Olduvai, formerly called Zinjanthropus, had a cranial capacity of just 530 cc (R. Leakey 1973a, p. 450). The ER 1470 skull was in fact as large as some smaller Homo erectus skulls, which range between 750 and 1100 cc. The average human skull is about 1400 cc. Among adult humans, the very lowest cranial capacities are in the low 800s (Brodrick 1971, p. 84).

Viewed from the rear, the sides of the reconstructed ER 1470 skull were nearly vertical, as in Homo sapiens. In Australopithecus and Homo erectus, the sides of the skull, seen from the rear, slope noticeably towards each other at the top (Figure 9.1, p. 556). Furthermore, the domed forehead of ER 1470 was not as receding as that of Australopithecus or Homo erectus, and the brow ridges were smaller. The skull walls of ER 1470 were thinner than those of Australopithecus or Homo erectus. Also, the foramen magnum, the opening in the base of the skull for the spinal cord, was located farther forward than in Australopithecus. In other words, several features of the somewhat primitive ER 1470 skull were characteristic of advanced species of the genus Homo ( Fix 1984, pp. 50–51; R. Leakey 1973a, p. 448 ).

Richard Leakey initially hesitated to designate a species for the ER 1470 skull, but eventually decided to call it Homo habilis. This strengthened the evidence for Homo habilis from Olduvai Gorge, announced by Louis Leakey in the 1960s.

What made the ER 1470 skull so unusual was its age. The stratum yielding the skull lay below the KBS Tuff, a volcanic deposit with a potassium-argon age of 2.6 million years. The skull itself was given an age of 2.9 million years, as old as the oldest australopithecines. The KBS Tuff’s age was later challenged, with critics favoring an age of less than 2 million years (Section 11.6.5 ).

 11.6.2 Evolutionary Significance of the ER 1470 Skull

Louis Leakey was pleased with his son’s discovery. ER 1470 vindicated his long-held view that a line of human ancestors, separate from Australopithecus and Homo erectus, extended far into the past.

Richard Leakey also believed his find had revolutionary implications for human evolution. “Either we toss out this skull or we toss out our theories of early man,” he wrote in National Geographic ( R. Leakey 1973b, p. 819). “It simply fits no previous models of human beginnings.” The model most widely accepted involved three steps. Australopithecus africanus, with some specimens as much as 3 million years old (Groves 1989, p. 198 ), gave rise to early Homo (H. habilis and then H. erectus), which in turn gave rise to Homo sapiens. But Leakey (1973b, p. 819) believed that the ER 1470 skull, larger and more humanlike than that of Australopithecus africanus, “leaves in ruins the notion that all early fossils can be arranged in an orderly sequence of evolutionary change.”

J. B. Birdsell (1975) of UCLA agreed this was true, even if the ER 1470 skull proved to be 2 million rather than 2.9 million years old. “From the very nature of its characteristics cranium 1470 does not seem to fit the standard scheme of the three grades of human evolution,” he wrote in the second edition of his textbook Human Evolution ( Fix 1984, p. 60).

In a National Geographic article, Richard Leakey included a chart showing two separate lines of hominid development. On one line, at about 3 million years ago, Leakey placed the ER 1470 hominid. Next on this line came Homo habilis at roughly 2 million years ago. At 1 million years ago, Homo habilis gave way to Homo erectus, which was followed at the very top of the chart by Homo sapiens.

The second (completely separate) line in Richard Leakey’s chart showed Australopithecus starting at 3 million years ago and finishing at 1 million years ago. Leakey (1973b, p. 819) commented: “Probably a relative rather than a forebear of mankind, apelike Australopithecus existed for at least 2 million years before it reached an evolutionary dead end.” Leakey believed, however, that further research would turn up a common ancestor for Australopithecus and the Homo line at around 4 million years ago.

Richard Leakey differed from his father by keeping Homo erectus in the direct line of human ancestry, “Most people would now agree that ‘1470’ should be called Homo habilis and that it is a direct ancestor of Homo erectus,” he wrote ( R. Leakey 1984, p. 154).

But the transition from ER 1470 to Homo erectus troubled Birdsell (1975), who wrote: “Anatomically in some ways such an evolutionary stage would seem retrogressive, for in a real sense it postulates that more archaic forms of men evolved out of a surprisingly advanced form, ER-1470” (Fix 1984, p. 137). Birdsell’s statement is of interest because the progression from Homo habilis to Homo erectus is one of the cardinal doctrines of recent evolutionary thought. If this progression turns out to be improbable, that would present severe problems for the conventional account of human evolution. The progression is arguably improbable because it involves, for example, going from skull ER 1470, with moderate brow ridges, to Homo erectus, with massive barlike brow ridges, back to Homo sapiens, with small brow ridges.

Such difficulties did not, however, trouble Richard Leakey. Recently, he said he considers Homo habilis and Homo erectus to be nothing more than early stages of one species—Homo sapiens (Willis 1989, pp. 154–155).

Richard Leakey has made other interesting statements about human beginnings. For instance, he wrote in his book Origins: “If we are honest we have to admit we will never fully know what happened to our ancestors in their journey towards modern humanity: the evidence is simply too sparse” (R. Leakey and Lewin 1977, pp. 11–12).

And in People of the Lake (R. Leakey and Lewin 1978, p. 17), Leakey said: “If someone went to the trouble of collecting together in one room all the fossil remains so far discovered of our ancestors (and their biological relatives) who lived, say, between five and one million years ago, he would need only a couple of large trestle tables on which to spread them out. . . . Yet with a confidence that may strike the uninitiated as something close to supernatural—if not to plain madness—prehistorians can now construct a view of human origins that is anything but crude, and may even bear some resemblance to the truth.” The evidence on the trestle tables would not, of course, be complete. Much has been suppressed or forgotten, and if it were placed back on the tables, it would be harder for confident prehistorians to construct plausible evolutionary lineages.

11.6.3 Humanlike Femurs From Koobi Fora

Some distance from where the ER 1470 skull had been found, but at the same level, John Harris, a paleontologist from the Kenya National Museum, discovered a quite humanlike upper leg bone. Harris summoned Richard Leakey (1973b, pp. 823, 828), who later reported: “Amid a mass of shattered elephant bone lay both ends of the femur of a remarkably advanced hominid. Further search turned up the missing pieces, parts of the tibia and a fragment of the fibula.

. . . John also discovered another femur. All these leg bones lay in deposits older than 2.6 million years. Do they belong to our new-found ‘1470 man?’ Frustratingly, we cannot be sure. It is quite clear, however, that these femurs are unlike those of Australopithecus, and astonishingly similar to those of modern man.” The femurs would later be attributed to Homo habilis.

The first femur, with associated fragments of tibia and fibula, was designated ER 1481 and the other ER 1472. An additional fragment of femur was designated ER 1475. Like the ER 1470 skull, the femurs were found on the surface. But Richard Leakey (1973a, p. 448) wrote in Nature: “The unrolled condition of the specimens and the nature of the sites rules out the possibility of secondary deposition—there is no doubt in the minds of the geologists that the provenance is as reported. All the specimens are heavily mineralized and the adhering matrix is similar to the matrix seen on other fossils from the same sites.” In other words, Leakey was certain the bones had recently weathered out of the fossil-bearing deposits from below the KBS Tuff.

Leakey (1973a, p. 450) stated in a scientific journal that these leg bones “cannot be readily distinguished from H. sapiens if one considers the range of variation known for this species.” In a National Geographic article, Leakey (1973b, p. 821) repeated this view, saying the leg bones were “almost indistinguishable from those of Homo sapiens.”

Comparing the newly found ER 1481 femur with a femur of Australopithecus, Leakey (1973b, p. 828) said: “The more ovoid, less robust shaft neck of Australopithecus implies that the latter, though capable of walking upright, did so only for short periods.” The “stronger neck shaft” of the new femur, Leakey (1973b, p. 828) added, “suggests its owner probably walked upright as his normal mode of locomotion.”

Concerning ER 1481, Richard Leakey (1973a, p. 450) wrote: “When the femur is compared with a restricted sample of modern African bones, there are marked similarities in those morphological features that are widely considered characteristic of modern H. sapiens. The fragments of tibia and fibula also resemble H. sapiens.” He further stated: “The head of the femur is large and set on a robust cylindrical neck which takes off from the shaft at a more obtuse angle than in known Australopithecus femurs” (R. Leakey 1973a, pp. 449–450).

Other scientists agreed with Leakey’s analysis. In 1976, B. A. Wood, anatomist at the Charing Cross Hospital Medical School in London, showed that in terms of three critical variables (femur neck length, femur head size, and femur neck shape), the ER 1472 and ER 1481 femurs always fell within a single standard deviation from the modern human mean. Wood (1976, p. 502) wrote: “The data . . . clearly show that femurs 1472 and 1481 from East Rudolf belong to the ‘modern human walking’ locomotor group.” Christine Tardieu (1981), also identified several humanlike features of the lower parts of the ER 1481 and ER 1472 femurs. Other workers found the femurs different from those of Homo erectus (Section 11.7.1).

Although most scientists would never dream of it, one could consider attributing the Koobi Fora femurs to a hominid very much like modern Homo sapiens, living in Africa about 2.9 million years ago (about 2.0 million years ago if you choose to believe the revised date of 1.9 million years for the KBS Tuff).

The ER 1472 and ER 1481 femurs show that distinctly anomalous discoveries are not confined to the nineteenth century. They have continued to occur with astonishing regularity up to the present day, right under our very noses, so to speak, although hardly anyone recognizes them for what they are. In Africa alone, we are building up quite a catalog: Reck’s skeleton, the Kanam jaw, the Kanjera skulls, the Kanapoi humerus, the Gombore humerus, and now the Lake Turkana femurs. All have been either attributed to Homo sapiens or described as being very humanlike. Except for the Middle Pleistocene Kanjera skulls, all were discovered in Early Pleistocene or Pliocene contexts.

11.6.4 The ER 813 Talus

In 1974, B. A. Wood (1974a, p. 135) described a talus (ankle bone) found between the KBS Tuff, then given an age of 2.6 million years, and the overlying Koobi Fora Tuff, with an age of 1.57 million years. Wood compared the fossil talus, designated ER 813, with hundreds of others, including those of modern humans, gorillas, chimpanzees, and other arboreal primates.

Using multivariate statistical techniques, Wood analyzed the ankle bones in terms of 3 angular and 5 linear measurements. He concluded: “In all the variates, the fossil aligned with the modern human tali” (Wood 1974a, p. 135). Wood further stated: “the functional implications of the canonical analysis results, combined with the close morphological affinity of the fossil talus with the modern human bones, make it possible that the locomotor pattern of this early hominid was like that of modern man” (1974a, p. 136).

If we accept the younger date for the KBS Tuff, the humanlike ER 813 talus would be 1.5 to 1.9 million years old, roughly contemporary with creatures designated as Australopithecus robustus, Homo erectus, and Homo habilis.

In a subsequent report, Wood (1976, pp. 500–501) said his tests confirmed “the similarity of KNM-ER 813 with modern human bones,” showing it to be “not significantly different from the tali of modern bushmen.” One could therefore consider the possibility that the KNM-ER 813 talus belonged to an anatomically modern human in the Early Pleistocene or Late Pliocene.

C. E. Oxnard (1975a, p. 121) wrote of ER 813: “description and examination using canonical analysis by Wood (1974) confirms that it is indeed very similar to modern man and is thus unlike the australopithecine specimens.” Challenging the ancestral status of Australopithecus, Oxnard (1975a, p. 121) added: “Unless evolution took the talus through a stage where it was much like man (as at East Rudolf), then through a stage where it was uniquely different from man (as at Olduvai and possibly Kromdraai), and back again to a stage like man (modern man), then australopithecine fossils had to have been unrelated to any direct human line.”

Of course, if the KNM-ER 813 talus really did belong to a creature very much like modern human beings, it fits, like the ER 1481 and ER 1472 femurs, into a continuum of such finds reaching back millions of years. In this case, any talk of an evolving human line, to which hominid fossils different from those of modern humans may be related, directly or indirectly, becomes irrelevant.

11.6.5 The Age of The KBS Tuff

The KBS Tuff was named after Kay Behrensmeyer, the Yale geologist who first identified it. Such volcanic tuffs can be dated by the potassium-argon method. If the dated tuff can be properly traced over difficult terrain, it can be used to determine a minimum age for fossils found below it. Over the years, workers obtained differing potassium-argon ages for the KBS Tuff, with substantial impact on the dating of fossil hominids at Lake Turkana.

The potassium-argon (K/Ar) method relies on the decay of radioactive potassium 40 into argon, a stable gas. In principle, one can, by correctly measuring the amounts of potassium and argon in a sample, calculate its age. The more argon, the older the sample.

In practice, there are many difficulties in using this method. For the age range in question (2– 4 million years), the accumulation of argon is very small. The measurements are thus extremely sensitive to any artificial loss or gain of argon.

Exposed to weathering, a sample may lose some of its argon. In this case, the measured age would be younger than the sample’s true age. If materials from older deposits get mixed into a sample, thus adding argon, the measured age would then be older than the true age of the sample.

In testing a sample, this question always arises: Has there been any argon loss or gain? In making such judgements, the investigator has wide latitude for personal interpretation.

Illustrating the difficulties inherent in the potassium-argon method, scientists have obtained ages ranging from 160 million to 2.96 billion years for Hawaiian lava flows that occurred in the year 1800. A report in the Journal of Geophysical Research stated: “It is possible that some of the abnormally high potassium-argon ages . . . may be caused by the presence of excess argon contained in fluid and gaseous inclusions” ( Funkhouser and Naughton 1968, p. 4606).

Potassium-argon tests often yield such unexpected results, far older or younger than the generally accepted ages for the formations being dated. One researcher (Woodmorappe 1979) compiled a list of 275 discrepant potassiumargon dates. From his tables, we have selected a few representative dates from the geological era most relevant to our study, the later Tertiary (Table 11.3).

In a potassium-argon study of formations in the western United States, geologist R. L. Mauger (1977, p. 37) stated: “In general, dates in the ‘correct ball park’ are assumed to be correct and are published, but those in disagreement with other data are seldom published nor are discrepancies fully explained.” And geologist J. B. Waterhouse (1978, p. 316) noted: “It is, of course, all too facile to ‘correct’ various values by explanations of leakage, or initially high concentrates of strontium or argon.

These explanations may be correct, but they must first be related to a time line or ‘cline of values’ itself subject to similar adjustments and corrections on a nonstatistical and nonexperimental basis.”

This raises an important issue. E. T. Hall (1974, p. 15), director of Oxford’s Research Laboratory for Archaeology and the History of Art, warned: “the greatest temptation is the one which leads an archaeologist selectively to believe evidence which seems to confirm the theories upon which he thinks his professional reputation rests. When the evidence comes from complex scientific techniques which are error prone and involve principles not wholly understood even by the scientists themselves, the dangers are great indeed.”

Potassium-argon dating is such an error-prone technique. When, however, ordinary persons, or even scientists in disciplines other than those directly connected with the paleoanthropological enterprise, hear that a fossil has been dated by the potassium-argon method, they think the matter has been settled by science in a thoroughly reliable fashion. But when one gets beyond the screen of footnotes and suitably restrained phrasing in paleoanthropological reports, one frequently discovers that the dating is quite nebulous. The strongest argument in favor of a particular date is often the personal commitment of a scientist whose ideas are supported by the date.

Radiometric dates, said E. T. Hall (1974, p. 15), “tend to acquire a spurious infallibility for the layman or for quasi-scientists like archeologists. They believe because they want to believe.”

11.6.5.2 The Potassium-Argon Dating of the KBS Tuff

In 1969, Richard Leakey sent samples of the KBS tuff to England for potassiumargon testing. According to E. T. Hall (1974, p. 15), the age obtained was a seemingly impossible 220 million years.

In 1970, F. T. Fitch and J. A. Miller, having received new samples, ran more potassium-argon tests and decided that the KBS Tuff was 2.6 million years old.

In 1972, Richard Leakey discovered the ER 1470 Homo habilis skull. Because the skull came from well below the KBS Tuff, he assigned it an age of 2.9 million years. This was controversial, because it made Homo as old as the oldest Australopithecus.

Results of paleomagnetic studies by Dr. A. Brock of the University of Nairobi confirmed the potassium-argon date given by Fitch and Miller for the KBS Tuff. ( For an explanation of the paleomagnetic dating method, see Section 9.2.10.)

Brock found that samples in and near the KBS Tuff were of normal polarity (Brock and Isaac 1974, p. 346). This was consistent with the potassium-argon date of 2.6 million years obtained by Fitch and Miller, which, if correct, falls in the upper part of the Gauss Normal Epoch (Figure 11.8). Below the KBS Tuff, the samples were predominantly of normal polarity. But Brock also found in this region two short intervals of reversed polarity, which he identified with the Kaena and Mammoth Events (Brock and Isaac 1974, p. 346). This tended to confirm that the KBS Tuff was in the Gauss Normal Epoch and was somewhere between 2.5 and 2.9 million years old.

Figure 11.8. This is the standard paleomagnetic polarity scale (after Wu, X. and Wang, L. 1985, p. 36). Brock and Isaac (1974) believed the polarity sequence at Koobi Fora supported an age of 2.6 million years, in the Gauss Normal Epoch, for the KBS Tuff.

Brock stated that skull ER 1470 came from “a level equivalent to that in which the Kaena and Mammoth events have been identified” (Brock and Isaac 1974, p. 347). He added: “An age of 2.7 to 3.0 Myr . . . is strongly indicated” (Brock and Isaac 1974, p. 347). Referring to the potassium-argon dates by Fitch and Miller, Brock concluded that “in every case the isotopic and paleomagnetic dates are consistent” (Brock and Isaac 1974, p. 347). Brock also found his version consistent with the faunal chronology prepared by Vincent J. Maglio.

Maglio identified marker fossils in the hominid-bearing sediments of the Lake Turkana sites. Skull ER 1470 was found in the zone containing Mesochoerus limnetes, an extinct pig. Maglio compared the pig teeth found at Lake Turkana with those found at the Shungura site in Ethiopia, where it had been demonstrated that the pig teeth increased in size with the passage of time. At Shungura, teeth of the size found at Lake Turkana fell in a time period extending from 1.8 million to 2.7 million years ago.

Maglio (1972, p. 383) noted: “The indicated age range includes the K /Ar date of 2.6 m.y. for the KBS tuff located within the sedimentary unit containing this fauna.” Richard Leakey believed that Maglio’s report supported his position on the ages of the KBS Tuff and the important ER 1470 skull.

But other scientists, who had different ideas about the relative antiquity of Australopithecus and Homo, were not happy about the potassium-argon age of 2.6 million years for the KBS Tuff (Johanson and Edey 1981). They pointed to new faunal studies that seemed to make the KBS Tuff much younger.

Basil Cooke (1976), for example, said the size range of pig teeth from below the KBS Tuff matched that of Ethiopian pig teeth with an age of 2 million years. If this correlation were accepted, the KBS Tuff would have to be less than 2 million years old.

Richard Leakey proposed differential rates of evolution as a possible explanation. Perhaps the pigs at Lake Turkana and their teeth got bigger earlier than those in Ethiopia because of a more favorable environment.

The dispute over the pig teeth and the KBS Tuff was a major topic at a February 1975 conference in London. Fitch and Miller presented the results of new potassium-argon tests, which yielded an age for the KBS tuff of 2.4 million rather than 2.6 million years (R. Leakey 1984, p. 167).

Another group of scientists showed uranium fission track evidence confirming the new potassium-argon date of 2.4 million years (R. Leakey 1984, p. 168). When uranium 238, a radioactive element, decays into lead, particles released during fission leave tracks in zircon crystals. By measuring the amount of uranium and counting the tracks in the crystals, one can estimate the crystals’ age.

At the London meeting, Basil Cooke used his fossil pig evidence to dispute the potassium-argon and fission track dates. But Richard Leakey (1984, p. 168), who did not regard Cooke’s results as conclusive, strongly defended the potassium-argon age of 2.4 million years for the KBS Tuff.

Not long afterward, Garniss Curtis of the University of California published his own potassium-argon test results (Curtis et al. 1975, p. 395). He obtained ages of 1.6 million and 1.8 million years for the KBS Tuff.

Curtis said the samples tested by Fitch and Miller were probably contaminated with argon from older inclusions. Fitch and Miller said Curtis’s samples possibly suffered argon loss, giving a date younger than the actual date of the tuff. Who was right? From the information provided in the published reports, it is hard to tell.

In one of their reports, Fitch and Miller (1976) did, however, give an interesting insight into potassium-argon dating procedures. They arranged some of their dated samples from the KBS Tuff into 4 groups, having average ages of 221 million years, 3.02 million years, 8.43 million years, and 17.5 million years.

They also listed over a dozen other individual samples with ages ranging from 0.52 to 2.54 million years. This bewildering array of dates comprises the actual results of the potassium-argon testing of samples from the KBS Tuff.

All dates older and younger than the ones finally published were thrown out, mainly because the researchers assumed the samples had been in some way contaminated or degassed. They proposed, for example, that flowing water could have mixed new and old volcanic materials or that water from hot springs could have released argon originally trapped in the sampled material (Fitch and Miller 1976, p. 125).

When Anthony J. Hurford and his associates published the conclusions of their fission track test, presented in preliminary form at the 1975 London meeting, they, like Fitch and Miller, disputed the 1.8 million year date for the KBS tuff obtained by Curtis. They stated: “Fission-track dating of zircon separated from two pumice samples from the KBS Tuff in the Koobi Fora Formation, in Area 131, East Rudolf, Kenya, gives an age of 2.44±0.08 Myr for the eruption of the pumice. This result is compatible with the previously published K-Ar and 40Ar/39Ar age spectrum estimate of 2.61±0.26 Myr for the KBS Tuff in Area 105, but differs from the more recently published K-Ar date of 1.82±0.04 Myr for the KBS Tuff in Area 131. This study does not support the suggestion that pumice cobbles of different ages occur in the KBS Tuff” (Hurford et al. 1976, p. 738).

Curtis had suggested that the Fitch and Miller dates of 2.61 and 2.42 million years were the result of older pumice included in the KBS tuff. Hurford also pointed out that his results were compatible with the paleomagnetic results obtained earlier by Brock and Isaac (Hurford et al. 1976, p. 740).

In another development, it turned out that Curtis’s potassium-argon age for the KBS Tuff was “flawed by an improperly adjusted weighing balance” (Johanson and Shreeve 1989, p. 99).

Meanwhile, Richard Leakey commissioned John Harris and Tim White to study the faunal conclusions reached by Basil Cooke. As it turned out, their investigation confirmed Cooke’s results. Leakey, as leader of the Koobi Fora project, prevailed upon Harris to remove any mention of how this faunal evidence related to the hominids of Lake Turkana. White, in protest, asked to have his name removed from the paper before it was published. Harris did not remove White’s name. The paper was rejected by Nature, but a revised version was published by the American journal Science in 1977 (Johanson and Edey 1981, pp. 240 –242).

The controversy dragged on for several years. The younger age for the KBS Tuff was very much favored by Don Johanson and Tim White, who promoted Australopithecus afarensis (including “Lucy”) as the ultimate ancestor of both Homo habilis and Australopithecus africanus. Afarensis was around 3 million years old. The skull of afarensis was typically australopithecine, smallbrained with heavy brow ridges. Having the much bigger, smooth-browed ER

1470 cranium at around 2.9 million years, as Richard Leakey originally suggested, would have made afarensis an unlikely ancestor of ER 1470, classified as Homo habilis.

In order to put an end to the controversy, Richard Leakey decided to call in additional researchers. “It was only in 1980,” wrote Leakey, “that a broad consensus was finally achieved. . . . Glynn [Isaac] and I decided we should invite other geophysicists to work on the KBS date. Eventually we managed to arrange for several different laboratories to evaluate the same material from split samples, using two methods: fission-track dating, as well as conventional potassiumargon. This was done quietly and with little fanfare. As a result, it became quite clear that the KBS tuff is no more than 1.9 million years old . . . it would be prudent to think of the skull KNM-ER 1470 as being about two million years old” (R. Leakey 1984, p. 170).

The case of the KBS Tuff is intriguing. Initially, Leakey had potassiumargon dates, faunal evidence, paleomagnetic dates, and fission track dates supporting an age of 2.6 million years. Then, a few years later, he said new potassiumargon dates, faunal evidence, and fission track dates favored an age of 1.9 million years.

Richard Leakey’s allusion to consensus is instructive. Researchers party to such an agreement may announce that their consensus must be correct because it is supported by dating methods A, B, and C. But as we have seen, various dating methods tend to give age ranges broad enough to support a number of age determinations.

Many place excessive, even unquestioning, faith in published age determinations, unaware of the many sources of error inherent in current dating methods. They do not adequately appreciate the crucial role that the judgements of individual researchers play in arriving at a published date from among the spread of dates often obtained from a series of tests. These complex judgements can easily be influenced by the researcher’s expectations and preconceptions.

11.7 Oh 62: Will The Real Homo Habilis Please Stand Up?

Artists, working from fossils and reports supplied by paleoanthropologists, have typically depicted Homo habilis as having an essentially humanlike body except for its apelike head (Figure 11.9).

Figure 11.9. Left: This drawing (after Johnson and Edey 1981, p. 286) shows Homo habilis, as generally depicted before 1987. Below the head, the anatomy is essentially human. Right: After OH 62 was found at Olduvai Gorge in 1987, a new picture of Homo habilis (after Budiansky 1987, p. 10) emerged, far smaller and more apelike than before.

Occasionally, scientists have raised questions about such depictions. “Were the australopithecines hairy? Was Homo habilis slightly less hairy, just to give it a hint of human respectability?” asked Richard Leakey. “Certainly, all the portraits ever painted of our ancestors show this kind of pattern. But as no artist has ever seen a living hominid, and as we have no way of knowing whether they were naked or not, it will remain a favorite topic of after-dinner speculation and fantasy forevermore” ( Leakey and Lewin 1978, p. 66).

In any case, a very humanlike portrait of Homo habilis persisted until 1987. In that year, Tim White and Don Johanson reported they had found in lower Bed I at Olduvai the first Homo habilis individual (OH 62) with postcranial bones clearly associated with a cranium.

Johanson and his coworkers (1987, p. 205) stated: “This specimen’s

craniodental anatomy indicates attribution to Homo habilis, but its postcranial anatomy, including small body size [ less than 3.5 feet] and relatively long arms, is striking similar to that of some early Australopithecus individuals.” Drawings of the new Homo habilis (Figure 11.9) were decidedly more apelike than those of the past.

Wood (1987, p. 188) noted: “The shape and size of the proximal femur, and the anatomy and relative lengths of the limb bones, both run counter to the view which sees H. habilis as a biped with a postcranial skeleton that is essentially modern human in its morphology, proportions and, by inference, function.”

Johanson and his coworkers (1987, p. 209) concluded it was likely that scientists had incorrectly attributed to Homo habilis many postcranial bones discovered prior to 1987.

11.7.1 Implications for the eR 1481 and eR 1472 Femurs

The OH 62 find supports our suggestion that the ER 1481 and ER 1472 femurs from Koobi Fora, described as very much like those of modern Homo sapiens (Section 11.6.3), might have belonged to anatomically modern humans living in Africa during the Late Pliocene. These femurs have been attributed by some workers to Homo habilis and by others to Homo erectus. But these attributions are questionable. Showing this will, however, take a few paragraphs of unavoidably obscure and intricate analysis of bone morphology.

In his book Lucy’s Child (Johanson and Shreeve 1989, photo section), D. Johanson suggested that the comparatively large ER 1481 femur was the Homo habilis male counterpart to the smaller OH 62 female Homo habilis femur.

But the attribution of the ER 1481 femur to the same species as OH 62 involves a

Figure 11.10. (Traced from Johanson and Shreeve 1989, photo section.) According to D. Johanson, the KNM-ER 1481 femur from Koobi Fora, Kenya, is from a male Homo habilis. It is, however, much larger than the OH 62 female Homo habilis femur from Olduvai Gorge. Attributing both femurs to the same species implies an unusual degree of sexual dimorphism. They display a greater size difference than the male (AL 333-3) and female (AL 288) Australopithecus afarensis femurs from Hadar, Ethiopia. Some workers have said that the degree of sexual dimorphism in the Hadar sample is too great to be accommodated within a single species. The same may be true of the KNM-ER 1481 and OH 62 femurs.

remarkable degree of sexual dimorphism for Homo habilis. The ER 1481 femur is much bigger than the OH 62 female femur (Figure 11.10).

Johanson believed, however, that the femurs of Lucy (AL 288) and a male hominid (AL 333-3) from the Hadar, Ethiopia, site displayed a degree of sexual dimorphism similar to that of the OH 62 and ER 1481 femurs. This made it conceivable, to Johanson, that the OH 62 and ER 1481 femurs might belong to a single species of hominid. To us, however, the degree of sexual dimorphism in OH 62 and ER 1481 appears much greater than that in the Hadar femurs.

Furthermore, although Johanson thought that both Hadar femurs belonged to one species (Australopithecus afarensis), other paleoanthropologists have said that the AL 333-3 femur, along with many other fossils attributed by Johanson to Australopithecus afarensis, actually belonged to Homo individuals (Groves 1989, pp. 260–263).

One of these workers (Zihlman 1985, pp. 216–217) demonstrated that putting all the Hadar hominids in one species would involve sexual dimorphism more extreme than that encountered in the most sexually dimorphic anthropoid apes (Section 11.9.8). Zihlman therefore believed Johanson was not justified in assigning all the Hadar fossils to a single species.

If the Hadar fossils were too sexually dimorphic to be included in one species, we believe the same would be true of the ER 1481 and OH 62 femurs, which seem to manifest an even greater degree of sexual dimorphism than the Hadar femurs.

Johanson’s attribution of the ER 1481 and OH 62 femurs to a single species appears to be a consequence of his belief that only one hominid species other than Australopithecus boisei (namely, Homo habilis) existed around 2 million years ago in East Africa ( Willis 1989, p. 263).

As we shall see in Section 11.7.5, some workers have suggested that Homo habilis represents at least two species, including, perhaps, an australopithecine. Wood (1987), for example, proposed that small, apelike OH 62 might represent an East African gracile australopithecine rather than Homo habilis.

Accepting this, one might try to keep the traditional picture of Homo habilis. One could then, as previously, attribute the ER 1481 and ER 1472 femurs to Homo habilis, as represented by the somewhat humanlike ER 1470 skull. But the ER 1481 and ER 1472 femurs were found some distance from the ER 1470 skull, which means there is no solid reason to connect them. Attribution of the ER 1481 and ER 1472 femurs to Homo habilis is therefore questionable.

Some workers have suggested that the ER 1481 and ER 1472 femurs, and other bones attributed to Homo habilis, should be attributed to Homo erectus (Wood 1987, p. 188).

Even before the discovery of OH 62, Kennedy (1983) assigned the ER 1481 femur to Homo erectus. Kennedy’s view would involve extending the age of African Homo erectus from about 1.6 million to at least 2 million years, since femur ER 1481 was found below the KBS Tuff at Koobi Fora.

In coming to her conclusion, Kennedy relied on comparative analysis of several femoral shaft measurements. But Trinkaus (1984, p. 137) noted that out of these measurements only one, the midshaft diameter, showed a “significant difference” (more than two standard deviations from the mean) from a sample of early anatomically modern human femurs. Trinkaus’s early anatomically modern human sample i ncluded 24 fossil femurs from Cro-Magnon, Predmost, and other early Homo sapiens sapiens sites. We suspect, however, that if the midshaft diameter of ER 1481 were compared with a sample that represented the total variation among living humans, it would fall closer to the mean. The other femoral shaft measurements of ER 1481 reported by Kennedy all fell within the range of early anatomically modern humans. This suggests that ER 1481 might be assigned to Homo sapiens rather than Homo erectus.

There are other reasons why attribution of the ER 1481 and ER 1472 femurs to Homo erectus is questionable. Since the discovery of Java man in the 1890s, scientists have written numerous books and articles describing femurs said to be those of Homo erectus. But until recently, no femurs, or other postcranial bones, have ever been found in direct connection with a cranium of Homo erectus. Therefore, it is not absolutely certain that any of the femurs scientists had previously described actually belonged to Homo erectus individuals.

In 1984, however, members of Richard Leakey’s team found a Homo erectus boy (KNM-WT 15000) at Lake Turkana. KNM-WT 15000 was assigned an age of 1.6 million years. The skeleton comprised associated cranial and postcranial elements, including the femur (Brown et al. 1985, p. 788).

According to the discoverers (Brown et al. 1985, p. 791), several features of the KNM-WT 15000 Homo erectus femur were different from those normally encountered in Homo sapiens. Other workers (Johanson et al. 1987, p. 209) also called attention to “Australopithecus-like aspects of . . . proximal femoral anatomy in early Homo erectus (KNM-WT 15000).” On the other hand, several workers have found the KNM-ER 1481 femur to be very much like modern human femurs and unlike those of australopithecines (Section 11.6.3).

Furthermore, Day and Molleson (1973, p. 128) said that most of the hominid femurs generally attributed to Homo erectus (such as the OH 28 femur from Olduvai Gorge and the Sinanthropus femurs from Zhoukoudian) were unlike those of modern human beings.

But Day and Molleson found the Java man femurs from Trinil, generally classified as Homo erectus, to be distinct from the OH 28 and Chinese Homo erectus femurs and almost identical to those of modern humans. They thus concluded that the Trinil femurs belonged not to Homo erectus but to anatomically modern humans (Section 7.1.8). This may put Homo sapiens sapiens at the Trinil site about 800,000 years ago.

In a study by Wood (1976), the ER 1481 and ER 1472 femurs came closer to the human mean in several key features than the Trinil I femur, which Day and Molleson said was anatomically modern and distinct from that of Homo erectus.

All of this suggests that it would not be correct to assign the anatomically modern ER 1481 and ER 1472 femurs to either Homo erectus or Homo habilis.

11.7.2 The Leap From Oh 62 to Knm-Wt 15000

The discoverers of OH 62 had to grapple with the evolutionary link between the new, more apelike Homo habilis and Homo erectus. “The juxtaposition of an otherwise relatively derived H. erectus postcranium at ~ 1.6 Myr (KNM-WT 15000) and a postcranially primitive H. habilis at ~ 1.8 Myr (OH 62) may imply an abrupt transition between these taxa in eastern Africa,” they stated (Johanson et al. 1987, p. 209). In paleoanthropology, the term “derived” is applied to a skeletal element that has supposedly undergone a significant and progressive morphological change relative to the same element in a supposedly ancestral form.

The H. habilis-H. erectus transition proposed by Johanson involves some rather extreme morphological changes, including a big change in size. Richard Leakey, applying normal human growth patterns, said that the Homo erectus boy, who was 5.6 feet tall, would probably have grown to over 6 feet tall as an adult. The female OH 62, on the other hand, was only about 3.25 feet tall, smaller than Lucy, who was about 3.5 feet tall.

How tall were the OH 62-type males? That is hard to say. Some presumably male Australopithecus afarensis individuals from the same Hadar, Ethiopia, site as Lucy may have been as much as 5 feet tall. On this basis, one might propose that an OH 62-type male might have been almost 5 feet tall. But, as we have seen, some workers say the size difference between the large and small Hadar specimens is too great to be accommodated within a single sexually dimorphic species. It seems likely, therefore, that the male companion to the 3.25-foot-tall OH 62 adult female was not much more than 4 feet tall. Altogether, an evolutionary leap from small, apelike OH 62 to big, humanlike KNM-WT 15000 in less than 200,000 years seems implausible.

Advocates of the much-debated punctuational model of evolution, however, can easily accept the transition. Unlike the traditional gradualists, punctuationalists assert that evolution proceeds by rapid episodes of change interrupted by long periods of stasis. The periods of change are so brief, say the punctuationalists, that intermediate forms are rarely preserved in the fossil record. Punctuationalism can, therefore, accommodate a variety of troublesome evolutionary anomalies, such as the habilis to erectus transition proposed by Johanson.

“The very small body size of the OH 62 individual,” said its discoverers, “suggests that views of human evolution positing incremental body size increase through time may be rooted in gradualistic preconceptions rather than fact” (Johanson et al. 1987, p. 209). But punctuational views may also be rooted in preconception rather than fact. The paleontological facts, considered in their entirety, suggest that various ape-man-like and humanlike beings, including some resembling modern humans, coexisted throughout the Pleistocene, and earlier.

In summary, the OH 62 specimen, seen as Homo habilis, delivers a triple blow to conventional ideas about human evolution. (1) OH 62 shatters the prevailing humanlike portrayal of Homo habilis, as presented in book and magazine illustrations, television shows, and museum exhibits. (2) The primitive morphology of OH 62 raises questions about the taxonomic status of very humanlike postcranial bones, such as the ER 1481 femur, which have been attributed to Homo habilis. To what kind of hominid should they now be assigned? It is possible they belonged to an anatomically modern human species that coexisted with Homo habilis, the australopithecines, and Homo erectus around 2 million years ago in Africa. (3) The size and geological age of OH 62 make the conventionally accepted evolutionary transition from Homo habilis to Homo erectus less plausible. Of course, if one were to classify OH 62 as an australopithecine that would resolve some of these difficulties.

11.7.3 Conflicting Assessments of Other Homo Habilis Fossils