David Geary’s Shrinking Brain

David GearyNew research shows that over the past 30,000 years, human brains have shrunk. This is not a sign, however, humans are growing dumber but that evolution is causing the key motor to be leaner and more proficient. The average size has decreased roughly 10 percent during this period from 1,500 to 1,359 cubic centimeters.

The measurements were taken from skulls in Europe, the Middle East and Asia.

Other anthropologists, however, note that brain shrinkage isn’t surprising given that the larger and stronger we are the more gray matter is needed to control such a larger mass. The Neanderthal, a cousin of the homo Sapien, who vanished some 30 millennia ago, was much larger and had a bigger brain.

The Cro-Magnons who made cave paintings of large animals in the Lascaux cave over 17,000 years ago had the biggest brain and were stronger.

David Geary, a psychology professor at the University of Missouri researched the evolution of skull sizes 1.9 million to 10,000 years old as our cousins and ancestors lived in a more complex social environment. Professor Geary used population density to measure social complexity, with the hypothesis that the more humans there are living closer together, the better the exchange is between groups, the division of labor and interactions between people.

Brain size, they found, decreased as population increased.

Such downsizing, however, doesn’t mean modern humans are less intelligent than their ancestors, but that they developed in a different way.

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