The Bone Labyrinth

NOTES FROM THE SCIENTIFIC RECORD

A fundamental mystery tied to our origins — to what makes us human—can be summarized by a single question: Why are we so smart?

The evolution of human intelligence still puzzles scientists and philosophers. Yes, it’s possible to trace the growth of our brains from earlier hominins through the emergence of Homo sapiens some 200,000 years ago. But what remains unknown is why our species suddenly and inexplicably had a burst of intelligence 50,000 years ago.

Anthropologists refer to this moment in time as the Great Leap Forward. It appears in the fossil record as a sudden explosion of art, music, even advancements in weaponry. Anatomically, nothing had changed in the sizes of our brains to explain this leap of ingenuity, yet something fundamental must have occurred to cause that abrupt spike in intelligence and consciousness. Theories abound, attributing this event to climate change, to genetic mutations, even to alterations in diet and nutrition.

Even more disconcerting is that for the past 10,000 years our brains have been shrinking in size — by a full 15 percent as of today. What does this new change mean? What does it portend for our future? The answer may lie in solving the mystery of that Great Leap Forward. But as of yet, no firm conclusion has come to the forefront to explain this pivotal development in human history.

Until now.

And with the revelations found within these pages, a more disturbing question arises: Are we at the cusp of a second Great Leap Forward? Or are we doomed to fall backward once again?