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, many in their mid- to late 80s, lining the halls of a dimly lit facility, just sitting around, seemingly waiting to die. One was named Jim. His eyes seemed vacant, lonely, friendless. He could cry at the drop of a hat but otherwise spent the last years of his life mostly staring off into space. I switched channels. I stumbled upon a very young-looking Mike Wallace. The journalist was interviewing architect Frank Lloyd Wright, in his late 80s. I was about to hear a most riveting conversation.
“When I walk into St. Patrick’s Cathedral … here in New York City, I am enveloped in a feeling of reverence,” said Wallace, tapping his cigarette.
The old man eyed Wallace. “Sure it isn’t an inferiority complex?”
“Just because the building is big and I’m small, you mean?”
“Yes.”
“I think not.”
“I hope not.”
“You feel nothing when you go into St. Patrick’s?”
“Regret,” Wright said without a moment’s pause, “because it isn’t the thing that really represents the spirit of independence and the sovereignty of the individual which I feel should be represented in our edifices devoted to culture.”
I was dumbfounded by the dexterity of Wright’s response. In the space of a few moments, one could detect the clarity of his mind, his unshakable vision, his willingness to think outside the box. The rest of the interview was just as compelling, as was the rest of Wright’s life. He completed the designs for the Guggenheim Museum, his last work, in 1957, when he was 90 years old. But I also was dumbfounded by something else. As I contemplated Wright’s answers, I remembered Jim from the nursing home. He was the same age as Wright. In fact, most of the residents were. I was beholding two types of aging. Jim and Frank lived in roughly the same period of time. But one mind had almost completely withered, seemingly battered and broken by the aging process, while the other mind remained as incandescent as a light bulb.
What was the difference in the aging process between men like Jim and the famous architect? This question has intrigued the research community for a long time. Attempts to explain these differences led to many important discoveries. I have grouped them as answers to six questions.
1) Is there one factor that predicts how well you will age?
When research on aging began, this question was a tough one to answer. Researchers found many variables, stemming from both nature and nurture, that contributed to someone’s ability to age gracefully. That’s why the scientific community was both intrigued and cautious when a group of researchers uncovered a powerful environmental influence. One of the greatest predictors of successful aging, they found, is the presence or absence of a sedentary lifestyle.
Put simply, if you are a couch potato, you are more likely to age like Jim, if you make it to your 80s at all. If you have an active lifestyle, you are more likely to age like Frank Lloyd Wright—and much more likely to make it to your 90s. The chief reason for the longer life is that exercise improves cardiovascular fitness, which in turn reduces the risk for diseases such as heart attacks and stroke. But researchers wondered why the people who were aging well also seemed to be more mentally alert. This led to an obvious second question.
2) Were they more mentally alert?
Just about every mental test possible was tried. No matter how it was measured, the answer was consistently yes: A lifetime of exercise results in a sometimes astonishing elevation in cognitive performance, compared with those who are sedentary. Exercisers outperform couch potatoes in tests that measure long-term memory, reasoning, attention, and problem-solving skill. The same is true of fluid-intelligence tasks, which test the ability to reason quickly, think abstractly, and improvise off previously learned material in order to solve a new problem. Essentially, exercise improves a whole host of abilities prized in the classroom and at work.
What about people who aren’t elderly? Here, the number of studies done thins out. But in one case, researchers looked at more than 10,000 British civil servants between the ages of 35 and 55, grading their activity levels as low, medium, or high. Those with low levels of physical activity were more likely to have poor cognitive performance. Fluid intelligence, the type that requires improvisatory problem-solving skills, was particularly hurt by a sedentary lifestyle.
Not every cognitive ability is improved by exercise, however. Short-term memory, for example, and certain types of reaction times appear to be unrelated to physical activity. And, while nearly everybody shows some improvement, the degree varies quite a bit among individuals. It’s one thing to look at a group of people and note, as early studies did, that those who exercise are also smarter. It’s another thing to prove that exercise is the direct cause of the benefits. A more intrusive set of experiments needed
