Tyler Graham and Drew Ramsey are not evolutionary biologists but a science writer and a medical doctor, respectively, and their argument, summarized in their book The Happiness Diet, does not derive from !Kung practices but from modern humans. They argue as we do that our happiness and mental well-being are rooted in what we eat, and this is more than a matter of depression. For instance, trace brain-derived neurotrophic factor, or BDNF. In Spark, John called this chemical “Miracle-Gro for the brain.” It is the important link that explains why simple exercise can have such a profound effect on cognition and well-being, and we’ll have more to say about it in the next chapter, when we address movement. But nutrition affects BDNF, too. Eating a diet high in sugar decreases BDNF. Eating foods with folate, vitamin B12, and omega-3 fats increases BDNF in the brain, just as exercise does.
Graham and Ramsey examine a list of twelve micronutrients and vitamins: vitamin B12, iodine, magnesium, cholesterol, vitamin D, calcium, fiber, folate, vitamin A, omega-3s, vitamin E, and iron; each is plentiful in the very foods, like fresh fruits and vegetables, that we have eliminated from the modern industrial diet, and each is vital to brain health and well-being on very specific pathways. But this is just the beginning. We are starting to understand the phenomenon of bioavailability, which says that addressing the lack of a given vitamin or micronutrient is not simply a matter of adding a given amount back through a supplement. The body’s ability to absorb those nutrients is greatly influenced by the presence or absence of other nutrients. For instance, eating spinach with lemon helps the body absorb much more of the iron in the spinach. Eating eggs and cheese together delivers a better uptake of vitamin D and calcium.
What emerges is the rough outline of a picture far too complex to detail in a prescriptive diet, and in the end, that’s the point. Yes, we can keep track of some of this in the cultural wisdom that has evolved through the millennia, but in the end, we’re simply not able, as individuals, to account for all of it, to count the calories, read the labels, and total the RDAs for a long list of necessary nutrients. The case that emerges, then, is precisely the situation evolution prepared us for. We can only begin to satisfy the complex and highly evolved requirements of our bodies, especially our brains, through variety. That’s why evolution hard-wired us to value it so greatly.
And the fact is, no one understands this fundamental, innate drive for variety more than the modern-day marketers of industrial and processed food. Walk through the aisle of any convenience store or thumb through ads for fast-food chains, soft drinks, and box cereals. Note the variety, exotic names, every shape, color, and texture imaginable. This is what we crave. Then begin reading labels and note the predominance of the suffixes “-trose” and “-crose,” i.e., sugar, and of corn and corn derivatives, processed soybeans, trans fats, and flour. The variety is an illusion. Under the label and chemical colorings and aromas, it is the same deadly industrial blend.
All of this forms the outline of our prescription, and the first half we’ve already given you is indeed negative: to not eat sugar, dense carbohydrates like grains, and trans fats, which is to say processed foods. But this is really advice to reject the monotony of the modern industrial diet. We are not urging a diet or even calorie restriction; we are outlining a sustainable way of life, and it rests on variety: the profusion and explosion of flavors, colors, and textures that evolution tuned our senses to pursue. Nuts, root vegetables, leafy greens, fruits, fish, wild game, clean, cool water. Range far and wide. Eat well.
BACK TO MARY BETH STUTZMAN
We caught up again with Mary Beth Stutzman during a quiet summer’s evening in 2013 over dinner in a pleasant little restaurant at the mouth of northern Michigan’s Thunder Bay River. She was well. We ordered, and she decided to pass on the local lake-caught fish fillets, which on the surface may seem a bit odd, because she is an active booster of the local sport fishery and even has her own television show dedicated to the topic. It’s how she supports her community, and that’s part of what she is about and glad to do now that she is well.
But the restaurant’s fillets came breaded. No bread—no way. That’s the rule that made her well. That was the key she was looking for in all those years of traipsing to specialists and emergency rooms doubled over in pain. She found the solution not from any advice from an MD but by accident. Just about the time she thought she was going to die, a friend happened to bring her some cupcakes to cheer her up. The irony is, the friend himself knew better than to eat cupcakes, but he thought Mary Beth might like them. He also brought her a book on the paleo diet, which he himself had adopted and which was why he didn’t eat cupcakes. She read the book, particularly the section about a problem called leaky gut, which sounded terribly, achingly, shockingly familiar. Leaky gut is caused by eating dense, refined carbs and sugar. In all those years of seeing doctors and delivering long lists of symptoms, no one suggested this to her, let alone asked what she was eating. No one asked about her nutrition. She adopted the diet and got immediately and noticeably better. And better. And better. Food healed her. It’s as simple as that.
Now she is vibrant and alive, an exercise enthusiast, actively promoting fitness as fun. She is engaged with her family and happy.
“I can’t even describe how great I felt. It was like being born again. It was a feeling of how great it is to be alive. It was out of this world,” she told us.
And no, she is not a food fanatic; in fact, she loathes the term “paleo.” If you press her on this matter, she’ll simply label her diet “trending toward paleo.” She even allows herself occasional tastes of selected whole grains, and now and again a little ice cream with its sugar. She’s okay with a little lactose. And maybe this variation and experimentation, even more than her diet and recovery, are the lessons we’d like you to carry with you as we develop our story. Here, though, are some key points: First, her path to well-being began with diet, specifically with recognizing the basic fact that civilization’s grain and sugar were making her ill, and even—as a young woman—close to death. All she had to do to fix it was pay some reasonable attention to diet—nothing extreme, but simply head in the direction of eating the way humans were evolved to eat. Second, she used that knowledge to devise her own path through the pitfalls. But most important, once she started to get better, her path to well-being led beyond diet, through other areas like fitness, family, and community. You will see this happen to others as we go on. Not every pathway begins with diet and nutrition, although many do, and it’s hard to imagine getting better if nutrition is wrong. But in some way or another, we think every pathway begins with a lesson from evolution.
CAUTION: EVOLUTION RUNS BOTH WAYS
There is a popular myth about evolution: that it is progressive and leads only one way, to bigger, better, and smarter, to more complex. It can lead that way, because complexity takes time to assemble, so complex comes later. But so does simpler, and the koala bear, that cuddly icon of cute, is our favorite example. Koalas are interesting to biologists because they eat only one thing, eucalyptus leaves, so they inhabit these trees ubiquitous in Australia. As a result, they really never have to leave the trees; they can just sit and watch the world go by, day in, day out.
It wasn’t always so. Koalas once had a more diverse diet in their evolutionary history. The mark of this is inside their head, as their brain does not fill the entire space allotted for it in their skull. That’s because, coincident with adopting the narrower diet, their brain shrank, and evolution has not yet had time to make skull size compensate, so the tiny little brain rattles around in a too-big case. One single source of food. That, and they are sedentary. If the koalas wanted to retain the bigger brain that evolution gave them, they also needed to move, and this is the lesson we turn to next.
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Building and Rebuilding the Brain Through Movement
No one can be blamed for being confused about this matter, particularly those who follow health news in the popular press. Duelin
g headlines appear almost daily summarizing the latest published results and fronting pronouncements such as this one from a recent paragraph in the New York Times’ health section: “And in a just world, frequent physical activity should make us slim. But repeated studies have shown that many people who begin an exercise program lose little or no weight. Some gain.”
The fact is, we don’t care whether the studies like the ones reported here are the final word on the matter. (We don’t think they are.) The larger issue is far more important: these sorts of conclusions are irrelevant. Physical exercise is not about weight loss; it is about your well-being.
The British scientist Daniel Wolpert likes to begin his case with the sort of fundamental and vexing question that seriously shakes up our thinking: why do we have a brain? He expects the obvious answer: to think.
“But this is completely wrong,” he says. “We have a brain for one reason only: to produce adaptable and complex movements. There is no other plausible explanation.” He is saying that our brains are literally built on and inextricably tied to movement of our bodies. Movement builds our brain because movement requires a brain.
Wolpert’s career of researching this traces the same argument that people often use about basic intelligence: that computers can’t do what we do. After generations of trying, the best and brightest of computer science still have been unable to approach something like artificial intelligence, and what we mean by that is that we can’t program computers to perform music, exercise judgment, or write books. Wolpert thinks something is missing in this familiar argument: “While computers can now beat grand masters at chess, no computer can yet control a robot to manipulate a chess piece with the dexterity of a six-year-old child.”
This is because even the simplest of motions—a flick of a finger or a turn of the hand to pick up a pencil—is maddeningly complex and requires coordination and computational power beyond electronic abilities. For this you need a brain. One of our favorite quotes on this matter comes from the neuroscientist Rodolfo Llinás: “That which we call thinking is the evolutionary internalization of movement.”
The telling encapsulation of this argument is the case of the sea squirt, a primitive sea animal with a rudimentary nervous system. For part of its life, the squirt spends time moving but only to look for a spot where it can anchor itself in the path of a ready source of food. On doing so, its first act is to eat and digest its own brain; it doesn’t need one anymore because it no longer needs to move.
Yet this is the sort of linkage between brain and movement that holds up from sea squirt to human along the long evolutionary chain. The association is clear: the more a species needs to move, the bigger its brain—a relationship particularly pronounced in mammals. And although we don’t often think of it this way, the argument gets its clincher with the great ape that (a) has the very largest of brains (we humans) and (b) happens to be the champion of movement. Coincidence, you think? One of our greatest and enduring fascinations as humans is with movement. Sedentary as we may be, we still pay enormous amounts of money and invest enormous amounts of cultural capital in watching people move, obviously so with sports but consider, too, movement like ballet. What other species could accomplish this level of variation and control in pure movement? Our attraction to ballet and dance is not coincidence, just as our deep appreciation for a naked human body of the gender that attracts us is not coincidence. This attraction is evolution’s way of making us pay attention to what matters, and movement matters. Evolution has made us think that graceful movement is beautiful.
BRAIN BUILDING
Neuroscience in the ’90s delivered a game-changing set of realizations that shone a couple of bright lights in new directions on the concepts of neuroplasticity and neurogenesis. The first says your brain is plastic in the prechemical sense of the word, malleable, shape-shifting, moldable. It is not the hardwired, compartmentalized organ we once thought it to be; it’s not true that given cells and networks of cells and given areas and structures of the brain are assigned a task and that’s that. Lose a set of cells to, say, a stroke, and you lose the ability to perform that task. Or, more to the point, get dealt a weak spot by genetics, say for language, and you will always have a struggle with language. But the brain can, in fact, rewire itself, repurpose bits and pieces. It can adapt. It grows. This is neuroplasticity.
Neurogenesis says something similar but even more revolutionary. New cells and networks of the brain grow as needed, very much as muscles grow with exercise. In fact, new-era neuroscience says that the brain is a muscle. This is more than an analogy. As science began to understand these phenomena, it began to tease out mechanisms, the cascades of signals and biochemicals that triggered this exquisite set of responses. This line of inquiry greatly illuminated what evolutionary biologists had already realized: that big brains and intricate physical movement went together, that evolution had in fact used some of the same principles to signal brain growth that it had used to signal muscle growth. Through time, evolution used biochemistry to enhance muscles, movement, and brains.
So far in our story, we have relied often on the concept of homeostasis, which is an array of signaling mechanisms within the body that responds to shocks or changes in the environment to return systems to a normal operating state. We’ll see it again and again to the point of ramping up to a new level of complexity and a new idea as our argument develops. All in time. But at this point in the discussion we need another related idea: hormesis. Hormesis is a biological response to low doses of a stressor, such as a toxin, that improves the ability of the body to handle that toxin. It can be applied to exercise. Unlike homeostasis, hormesis does not return the body to a normal state. It returns it to a better-than-normal state. When a bodybuilder lifts weights, he is placing heavy stress on a given set of muscles, a process that damages them by overload. The body reacts with an immune response and inflammation. And now notice that we have introduced two troubling words into the discussion, at least troubling in terms of the popular understanding: inflammation and stress. The fact is, the body uses both to rebuild, and we’ll argue later for a more refined appreciation of these forces.
But for now, the important point is that rebuilding the body does not simply build back what was torn down: it builds bigger and better, an adaptive response. Your muscles face a new challenge in the form of heavier weights, so the body responds by building infrastructure to meet that challenge. It grows and makes the body more resilient. Take the challenge away, and the body heads in the other direction: once again, use it or lose it.
And now we come back to BDNF, brain-derived neurotrophic factor, the Miracle-Gro of the brain. Movement places demands on the brain, just as it does on muscle, and so the brain releases BDNF, which triggers the growth of cells to meet the increased mental demands of movement. But BDNF floods throughout the brain, not just to the parts engaged in movement. Thus, the whole brain flourishes as a result of movement. It provides the environment that brain cells need to grow and function well.
Chemically, there is more to this story—lots more. For instance, exercise also triggers responses in the important neurotransmitters long studied in connection with issues like addiction and depression, chemicals like serotonin, dopamine, and norepinephrine. These are parallel processes. It all hangs together. But in the end, cells are cells. The brain is an energy-burning network of specially adapted cells like any other organ and is wrapped up in the health of the rest of the system. This ought to follow logically from the connection between the brain and movement: if the body needs stronger or more refined movement to meet a given challenge, it will need more brain circuitry to guide that movement. It would make no sense adaptively to build one without the other, so we need the biochemical provisions to do both.
This is no longer conjecture or theoretical construct. We may be a sedentary culture, but while we’ve been couch-bound in front of video games and computer monitors, science has been busy assembling a massive pile of evidence that says the qu
ickest, surest path to the health and well-being of the brain and body is movement, or vigorous aerobic exercise.
Begin by considering a formal review of the literature, now more than a decade old but with conclusions that have even more support today. Writing in the Journal of Applied Physiology, researchers including Frank W. Booth laid out the case that inactivity was a looming factor in at least twenty “of the most chronic disorders.” Yes, it does include obesity, but it extends far beyond to other afflictions of civilization, including congestive heart failure, coronary artery disease, angina and myocardial infarction, hypertension, stroke, type 2 diabetes, dyslipidemia, gallstones, breast cancer, colon cancer, prostate cancer, pancreatic cancer, asthma, chronic obstructive pulmonary disease, immune dysfunction, osteoarthritis, rheumatoid arthritis, osteoporosis, and a range of neurological dysfunctions, a subcategory of particular interest here and one we will unpack in a moment.
In almost all of these cases, the causes of the disease are directly linked to inactivity, but not all. For instance, Booth concludes that there is no evidence saying inactivity causes chronic obstructive pulmonary disease. That is, exercise may not prevent it but can heal it once it does occur—an important distinction. This is the realization that ought to ring through public discourse like a loud pealing bell, given that the list cited above is hugely responsible for the crushing burden of health-care costs in our society—and yet almost nowhere in the widespread discussion of reducing those costs do we mention how much of that bill is traceable to our sedentary ways.
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