Why Endurance Matters: The Human Brain is Getting Smaller

     About three years ago, when I finished writing a book on the adventure of running America's largest ultramarathon, I titled the manuscript Running Wild.  Before going to press, the publisher changed the title to The Longest Race: a Lifelong Runner, an Iconic Ultramarathon, and the Case for Human Endurance.  I thought it sounded awfully textbooky, but in the publishing biz the title is usually the publisher's call.  Later, I wished I'd held out for Running Wild.
     The thing is, for 99 percent of our evolution as bipedal hunter-gatherers, we humans were wild.  For all those hundreds of thousands of years, our ancestors had to have enormous endurance and savvy just to survive.  A Paleolithic human was to a modern human what a wildcat is to a house cat, or a wolf to a dog, or an aurochs to a cow.  Now, we've been thoroughly domesticated.  We're cowed!
     The domestication of humans began with the advent of civilization, and with our growing dependence on technology to do what we'd previously depended almost entirely on our bodies and brains to do.  Today, we reflexively associate tech advancement with becoming smarter, and assume that while we may be physically weaker than our nomadic ancestors were, we're mentally far stronger.  But anthropological research says that may not be true.  Here's an excerpt from my forthcoming book, tentatively titled Racing to the End of the World:

   Between the beginning of civilization and today, it seems, the overall size of the human brain has apparently diminished by 15 to 20 percent.  In the last 500 years (the most recent 0.01 percent of our evolution), and especially in the past 50 years (the most recent 0.001 percent), equipped with our computers, Internet, and rockets, we have conquered the earth and are eyeing other planets—and meanwhile have lost a substantial part of the organ that enabled us to achieve that conquest.  Now, the conquerors are being conquered.  The size of the human brain peaked at about 1,500 cubic centimeters during the time of Early Modern Humans, or so-called Cro Magnon man, 20,000 to 40,000 years ago.  Now look what’s happened:

 

                              Cro Magnon Brain

(after 99.6 percent of our evolution:   1,500 cc

 

Modern Human Brain

(after just the subsequent 0.4 percent:  1,300 cc

 

  The most convincing confirmation of this came in 2010, when anthropologist Antoine Balzeau of the French Museum of Natural History examined the skull of a 28,000-year-old Cro Magnon skeleton that had been found in a cave in Dordogne, France.  Using advanced imaging technology, Balzeau made an endocast showing that the brain this skull once contained had been 15 to 20 percent larger than the modern human brain.  Other studies, cited by University of Wisconsin anthropologist John Hawks, indicate that the shrinkage since Cro-Magnon man has been about 10 percent, or 150 cubic centimeters—an amount of brain about the size of a Macintosh apple—the original kind, with a lower-case “a”.

   When I was a kid first learning about evolution, I heard science-fiction-inspired jokes about humans eventually becoming giant heads with tiny vestigial appendages.  But now, instead, the brain getting smaller?  Doesn’t that totally contradict what we know of human progress? And how could I not have heard of this?  It’s not that the evidence of a significant shrink is much questioned.  And I’m not a conspiracy theorist, but I can only infer that for some reason this shrinking of our brains is a thing that the media most of us depend on for news or stimulation have very little incentive to cover.  The U.S. economy—and increasingly the world’s—is heavily invested in consumer technology sales.   It is only lightly invested in serious education, environmental protection, human health, adaptation to the far-reaching ravages of global warming, preparation for the coming destruction of coastal cities, replacement of deteriorating roads, bridges, pipelines, water mains, and other costly infrastructure, and a long list of other urgent needs of the kind it will take hard use of our brains to meet.

      Consumer technology (including all the devices used to deliver passive entertainment, chatter, and distraction) generates the lion’s share of revenue that, through advertising and promotion, pays for and controls the major news media.  Just watch how much of the advertising is for cars, fast food, and drugs, along with a fair amount of “hey, we’re good guys” PR to appease those of us who have gotten too suspicious--like the BP ads in the wake of the Gulf oil rig disaster assuring us that BP is invested in America and is our friend.  As the Romans found, before their collapse, there are benefits to be gained by keeping the populace satisfied with “bread and circus.”  Their formulation was later updated by Marie Antoinette’s “Let them eat cake,” before her brain-severing demise, and more recently by the hugely profitable but debilitating American penchant for quelling anxiety with Twinkies, doughnuts, and fries.  There’s no political or commercial profit in pointing out that people may be getting dumber.