Editor's Letter: Our shrinking brains

last updated 8 January 2015

As if life weren’t complicated enough, now we have to get our heads around this: The human brain has been shrinking. A University of Wisconsin anthropologist has analyzed skulls unearthed by archeologists around the globe and concluded that over the last 5,000 years, human brains have shrunk by roughly 150 cubic centimeters, or a full 10 percent. The finding seems counterintuitive—you’d think that as civilization has gotten more complex, we would need more brain cells to function, not fewer. (Just try reading the 1,990-page House health-reform bill, for instance.) But evolution works in curious ways. As anthropologist John Hawks told? LiveScience.com last week, having moved away from our hunter-gatherer lifestyles, “we can rely on other people for more things, can specialize our behavior to a greater extent, and maybe not need our brains as much.”

I’m all for relying more on other people, shrinking brains or no. Still, with our species confronting such threats as global warming and nuclear proliferation, this would seem to be an inopportune time for any slippage in collective brainpower. Hawks does note that smaller brains are not necessarily weaker ones; their size reduction could reflect a more efficient use of glucose and the other resources that brains need to function. “Efficiency demands that the brain should be smaller,” Hawks said. “Maybe we got better with smaller brains, but maybe we’re getting dumber. How can we know?” There’s evidence to support either contention. On the one hand, we have used our dwindling brains to cure polio, land on the moon, and invent the Internet. Then again, Britney Spears now has nearly 4 million followers on Twitter.