Brain Rules (Updated and Expanded). John Medina

no other creature. It is as close to mind reading as we are likely to get.

      This ability to peer inside somebody’s mental life and make predictions takes a tremendous amount of intelligence and, not surprisingly, brain activity. Knowing where to find fruit in the jungle is cognitive child’s play compared with predicting and manipulating other people within a group setting. Many researchers believe a direct line exists between the acquisition of this skill and our intellectual dominance of the planet.

      When we try to predict another person’s mental state, we have physically very little to go on. Signs do not appear above a person’s head, flashing in bold letters his or her motivations. We are forced to detect something that is not physically obvious at all, such as fear, shame, greed, or loyalty. This talent is so automatic, we hardly know when we do it. We began doing it in every domain. Remember dual representation: the stick and the thing that the stick represents? Our intellectual prowess, from language to mathematics to art, may have come from the powerful need to predict our neighbor’s psychological interiors. As I said, your brain is amazing.

      Why did I want to spend time walking you through the brain’s survival strategies? Because they aren’t just part of our species’ ancient history. They give us real insight into how humans acquire knowledge. We improvise off a database, thinking symbolically about our world. We are predisposed to social cooperation, which requires constantly reading other people. Along with the performance envelope, these concepts determine at the most fundamental level how our brains work.

      Now that you’ve gotten the gist of things, let’s dive into the details.

      Brain Rule #1

      The human brain evolved, too.

      • The brain appears to be designed to (1) solve problems (2) related to surviving (3) in an unstable outdoor environment, and (4) to do so in nearly constant motion.

      • We started with a “lizard brain” to keep us breathing, then added a brain like a cat’s, and then topped those with the thin layer known as the cortex—the third, and powerful, “human” brain.

      • We adapted to change itself, after we were forced from the trees to the savannah when climate swings disrupted our food supply.

      • Going from four legs to two to walk on the savannah freed up energy to develop a complex brain.

      • Symbolic reasoning is a uniquely human talent. It may have arisen from our need to understand one another’s intentions and motivations. This allowed us to coordinate within a group, which is how we took over the Earth.

exercise

      Brain Rule #2

      Exercise boosts brain power.

      IF THE CAMERAS WEREN’T rolling and the media abuzz with live reports, it is possible nobody would have believed the following story:

      A man had been handcuffed, shackled, and thrown into California’s Long Beach Harbor, where he was quickly fastened to a floating cable. The cable had been attached at the other end to 70 boats, bobbing up and down in the harbor, each carrying a single person. Battling strong winds and currents, the man then swam, towing all 70 boats (and passengers) behind him, traveling 1½ miles from Queensway Bridge. The man, Jack LaLanne, was celebrating his birthday.

      He had just turned 70 years old.

      Jack LaLanne, born in 1914, has been called the godfather of the American fitness movement. He starred in one of the longest-running exercise programs produced for commercial television. A prolific inventor, LaLanne designed the first leg-extension machines, the first cable-fastened pulleys, and the first weight selectors, all now standard issue in the modern gym. He is credited with inventing an exercise that supposedly bears his name, the Jumping Jack. LaLanne lived to the age of 96. But even these feats are probably not the most interesting aspect of this famed bodybuilder’s story.

      If you watch him during an interview late in his life, your biggest impression will be not the strength of his muscles but the strength of his mind. LaLanne is mentally alert. His sense of humor is both lightning fast and improvisatory. “I tell people I can’t afford to die. It will wreck my image!” he joked to Larry King. He once railed: “Do you know how many calories are in butter and cheese and ice cream? Would you get your dog up in the morning for a cup of coffee and a donut?” (He claims he hasn’t had dessert since 1929.) He has the energy of an athlete in his 20s, and he is possessed of an impressive intellectual vigor.

      So it’s hard not to ask, “Is there a relationship between exercise and mental alertness?” The answer, it turns out, is yes.

      Survival of the fittest

      Though a great deal of our evolutionary history remains shrouded in controversy, the one fact that every paleoanthropologist on the planet accepts can be summarized in two words:

      We moved.

      A lot. As soon as our Homo erectus ancestors evolved, about 2 million years ago, they started moving out of town. Our direct ancestors, Homo sapiens, rapidly did the same thing. Because bountiful rainforests began to shrink, collapsing the local food supply, our ancestors were forced to wander an increasingly dry landscape looking for more trees to scamper up and dine on. Instead of moving up, down, and across complex arboreal environments, which required a lot of dexterity, we began walking back and forth across arid savannahs, which required a lot of stamina. Homo sapiens started in Africa and then took a victory lap around the rest of the world. The speed of the migration is uncertain; the number changes as we find new physical evidence of habitation and as we’re better able to isolate and characterize ancient DNA. Anthropologists can say that our ancestors moved fast and they moved far. Males may have walked and run 10 to 20 kilometers a day, says anthropologist Richard Wrangham. The estimate for females is half that. Up to 12 miles: That’s the amount of ground scientists estimate we covered every day. That means our fancy brains developed not while we were lounging around but while we were exercising.

      Regardless of its exact speed, our ancestors’ migration is an impressive feat. This was no casual stroll on groomed trails. Early travelers had to contend with fires and floods, insurmountable mountain ranges, foot-rotting jungles, and moisture-sucking deserts. They had no GPS to reassure them, no real tools to speak of. Eventually they made oceangoing boats, without the benefit of wheels or metallurgy, and then traveled up and down the Pacific with only the crudest navigational skills. Our ancestors constantly encountered new food sources, new predators, new physical dangers. Along the way they routinely suffered injuries, experienced strange illnesses, and delivered and nurtured offspring, all without the benefit of textbooks or modern medicine. Given our relative wimpiness in the animal kingdom (we don’t even have enough body hair to survive a mildly chilly night), what these data tell us is that we grew up in top physical shape, or we didn’t grow up at all. These data also tell us the human brain became the most powerful in the world under conditions where motion was a constant presence.

      If our unique cognitive skills were forged in the furnace of physical activity, is it possible that physical activity still influences our cognitive skills? Are the cognitive abilities of someone in good physical condition different from those of someone in poor physical condition? And what if someone in poor physical condition were whipped into shape? Those are scientifically testable questions. The answers are directly related to why Jack LaLanne can still crack jokes about eating dessert. In his nineties.

      Will you age like Jim or like Frank?

      Scientists discovered the beneficial effects of exercise on the brain by looking at aging populations. Years ago while watching television, I came across a documentary on American nursing homes. It showed people in wheelchairs,