Excerpt from The Genetics of Health
As Haruki Murakami writes, “I move, therefore I am”—no movement, no life. That’s not quite true if you ask a slumbering sloth. You should ask a sea squirt instead. These are fascinating creatures. The English neuroscientist Daniel Wolpert always uses the sea squirt as an example of why the brain evolved primarily for movement.
About 70 percent of our planet is seawater, so it is only natural that this constantly moving, majestic, and mellifluous body of liquid holds many secrets about our collective pasts. When we seek life on other planets, the first thing we look for is a sign of water. Even though the ocean is home to many unique and mysterious biological masterpieces, the sea squirt still remains one of my favorite creatures. This is an animal that has two life-forms—mobile and immobile. It begins life moving around on brightly colored, tentacle-like structures. Once it attaches itself to a rock, it begins to digest its brain, as the organ is redundant now. I said this in my recent TEDx Talk—if we find our rock and then spend our lives in front of a television, virtually immobile, we may as well eat our brains. As Wolpert put it in his 2011 TED Talk:
So think about communication—speech, gestures, writing, sign language—they’re all mediated through contractions of your muscles. So it’s really important to remember that sensory, memory, and cognitive processes are all important, but they’re only important to either drive or suppress future movements. There can be no evolutionary advantage to laying down memories of childhood or perceiving the color of a rose if it doesn’t affect the way you’re going to move later in life.
Actually that’s pretty logical because everything we do, we do because we move—for example, I am writing this book by moving many muscles: fingers typing on my computer keyboard, coffee-sipping lip muscles, eyebrows furrow as I consider this passage. Living life requires movement and, therefore, brain activity. Skin may sense touch, but without movement, our fingers or limbs cannot move toward an object we desire to touch. Movement is everything.
More and more, science points out that movement is not only essential, but it also actually makes our brains smarter in a kind of evolutionary feedback mechanism. In 2004, the evolutionary biologists Daniel E. Lieberman of Harvard and Dennis M. Bramble of the University of Utah published an article in the influential journal Nature, in which they hypothesized that our bipedal ancestors survived by becoming endurance athletes—by being able to chase and drag down prey. Most other fast animals like cheetahs can run very fast in short bursts, but cannot run for a long time. They are sprinters, not endurance runners.
However, when humans became upright, everything about our bodies evolved to make us walk and run, two legged, over great distances. When compared to other primates, humans developed longer legs, shorter toes, less hair, and convoluted inner-ear mechanisms to maintain balance and keep us stable when we stand or run upright.
With this increase in movement, something else was happening, almost miraculously—our brains were becoming larger. The human brain is proportionally three times as big when compared to other animals’ body size. In the beginning, people felt it was just because of increased movement. But increasingly, it appears endurance is also equally important. Dogs and rats, for example, are good endurance runners also, and these creatures also have larger-than-average brain sizes in proportion to their body sizes. Lieberman’s team specifically decided to test the importance of endurance. They compared mice that were trained at endurance running with standard mice, and they found that, after a few generations, the mice that had undergone these fitness workouts had activated new genes and had innately high levels of substances that promote tissue growth and health, especially a protein called brain-derived neurotrophic factor (BDNF). BDNF is in humans too, and it not only makes your endurance better, but it also drives brain growth. The phrase “jogging your memory” may indeed be more literal than we imagine.
The Lieberman study was followed by a study by David A. Raichlen, an anthropologist at the University of Arizona. He suggests the link between endurance exercise, especially leg movements, and the brain is thus: when an animal undertakes endurance exercise, they produce more BDNF in muscles. These muscles produce so much BDNF that some of this protein eventually ends up in the brain. The Canadian American cognitive scientist Steven Pinker’s writings often suggest that evolution is a sneaky component in any study of psychology. Therefore, if humans developed endurance to hunt prey, and thereby developed larger brains, this was also because they were growing their ability to think and better plan tracking prey—an evolutionary game of chess that fed both body and brain.
Speaking of chess, I met the Russian chess champion Garry Kasparov at THiNK, an ideas conference, when we were at a book signing together. Garry was signing copies of How Life Imitates Chess: Insights into Life as a Game of Strategy and I was autographing copies of my previous book Skin: A Biography. That was the biggest booksigning I’ve ever had to do at one event—250 copies one after another. We discussed chess and his battles with the IBM supercomputer Deep Blue. Garry felt that a human is always superior to a computer, even though computers were getting better. When I asked him if it was a lack of concentration that made him lose to a computer once, he replied in the negative—it was because he had forgotten to play like a human, full of impulse and irrationality. He was trying to best the computer in a memory game and got beaten. But it was something else he said that got me thinking: “If I were sitting in front of a chess board, moving solid chess pieces about, the computer would have never beaten me.” I’m not sure if Kasparov meant this, but therein is the answer, I reckon—to move chess pieces, we have to move many muscles, and this movement also makes our brain smarter. Daniel Wolpert would agree heartily. Wolpert says that it takes years to train a robot to pour a glass of water into different-sized cups, something a small child can master quickly. As long as we are moving something, the brain will do what it has to do much more efficiently and elegantly.