Only Human Brains Shrink

Next time you start to feel mentally superior to a chimp, think again. It turns out that while human brains shrink as they age, chimpanzee brains do not, a new George Washington University study has discovered. The findings upend the conventional wisdom that all primates saw their brains shrink over time, the Wall Street Journal explains—in fact, the researchers now suspect that only humans decline in this way.

“It seems that this is the cost,” says the head researcher, referring to humans' longer life spans. “We experience more extensive atrophy in the brain that results in this obvious shrinkage, of a kind that is not seen even in our closest relatives, chimpanzees.” Chimps also aren’t prey to the various neurological diseases linked to brain shrinkage—like Alzheimer’s and dementia. “We are very weird animals,” says one anthropologist. “This shows there is something really unusual about the late-life biology of the human species.” (More chimpanzees stories.)