Stephanie Pappas writes:

Over the course of the Pleistocene epoch, between 2.6 million years ago and 11,700 years ago, the brains of humans and their relatives grew. Now, scientists from Tel Aviv University have a new hypothesis as to why: As the largest animals on the landscape disappeared, the scientists propose, human brains had to grow to enable the hunting of smaller, swifter prey.

This hypothesis argues that early humans specialized in taking down the largest animals, such as elephants, which would have provided ample fatty meals. When these animals’ numbers declined, humans with bigger brains, who presumably had more brainpower, were better at adapting and capturing smaller prey, which led to better survival for the brainiacs.

Ultimately, adult human brains expanded from an average of 40 cubic inches (650 cubic centimeters) at 2 million years ago to about 92 cubic inches (1,500 cubic cm) on the cusp of the agricultural revolution about 10,000 years ago. The hypothesis also explains why brain size shrank slightly, to about 80 cubic inches (1,300 cubic cm), after farming began: The extra tissue was no longer needed to maximize hunting success.

This new hypothesis bucks a trend in human origins studies. Many scholars in the field now argue that human brains grew in response to a lot of little pressures, rather than one big one. But Tel Aviv University archaeologists Miki Ben-Dor and Ran Barkai argue that one major change in the environment would provide a better explanation [Continue reading…]