Life's Little Mysteries

Are Our Brains Shrinking?

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If not for our large brains, humans would still be poking at anthills with rudimentary stick tools instead of picking up our lunch at a drive-thru joint. The big wads of gray matter gave us the ability to solve problems, create complex language and, eventually, build civilization as we know it. So it comes as a bit of a shock to learn that the human brain is actually getting smaller, and an even bigger shock to find out that it has been decreasing  in size for some 20,000 years.

The modern human brain is about 10 percent smaller than that of the Cro-Magnon man that lived 20,000 to 30,000 years ago. Make a fist, subtract your pinky and ring fingers and that part of your palm. That's about how much brain has disappeared over time.

Losing a little brain doesn't necessarily mean that we've gotten dumber. In fact, quite possibly it means the opposite.

Brian Hare, an anthropologist at the Duke University Institute for Brain Sciences, recently told NPR that a smaller brain might actually be an indirect sign of higher intelligence.

Hare studies chimpanzees and bonobos . Both are similar to humans, as well as each other, but bonobos have smaller brains than chimpanzees, and are also much less aggressive. Both types of primates are good puzzle-solvers, Hare said, but when you give them a challenge that requires teamwork, chimpanzees are much more likely to flunk it. Bonobos, however, understand the importance of banding together.

"If the food is quite sparse and it's not easy to share, [bonobos] can solve the problem," Hare said. "Chimpanzees, in the same context — where there's not much food and it's not easy to share — they just refuse to work together. They can't solve the problem, even though they know how."

If there's anything smarter than enlisting friends to help get you food, I can't think of it.

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Follow Bjorn Carey on Twitter @thebjorncarey

Bjorn Carey is the science information officer at Stanford University. He has written and edited for various news outlets, including Live Science's Life's Little Mysteries, and Popular Science. When it comes to reporting on and explaining wacky science and weird news, Bjorn is your guy. He currently lives in the San Francisco Bay Area with his beautiful son and wife.