University of Arizona
EVOLUTION, ECOLOGY, AND THE WESTERN DIET
With a Glance at Jared Diamond, Michael Pollan, and Gary Nabhan
Our earliest primate precursors lived 25 million years ago, followed by various types of evolving apes until, 5 or 6 million years ago, hominids split off from chimpanzees, our nearest relative. In those earliest years, as they lived in trees and moved about the ground on all fours, our precursors were foragers, almost total vegetarians, lacking the physiques and brains needed to hunt anything more carnal than small animals over which they happened to trip. William Calvin, in A Brain For All Seasons, tells us that gorillas eat 50 pounds of vegetation a day to extract enough calories from the super high-fiber diets their jaws evolved to handle. Not until bipedal hominids became hunter-gatherers several million years ago did their fodder-rich, calorie-poor diets begin to include sufficient protein to promote brain growth, as a result of incorporating meat from hunting. With the appearance of Homo sapiens several hundred thousand years ago, root digging and soaking, primitive cooking, and eventually the start of farming (a mere ten thousand years ago) gradually began to alter the hominid diet even further.
Today, even though gut length and jaw size have shrunk, while brain size and complexity have increased, we are still, according to evolutionary biologists, basically the offspring of twenty million years of primate evolution. But as a result of settlements, civilization, and farming, to which were added the manufacturing skills from the industrial revolution, close to zero percent of today’s diet can be said to be found in nature: our foods have all been changed through processing. Yet we are still constituted for a high carbohydrate, moderate meat-eating diet. Our precursors could eat meat only after a kill. There were no refrigerators and freezers to stop rot and decay. Eat it now or do without! A binge stored body fat for lean days ahead. Today’s daily binges of meats and carbs are another story altogether.
Is it really possible, you may ask, that just about all the foods we eat today did not exist for 99.9% of “our” history? Yes. Except for a few wild raspberries you might find on a country walk, or some wild mushrooms, or milk from a family cow, the foods we eat today can be found only in a superfarm, a superfactory, or a supermarket.
Are these manufactured foods good for us or bad? As a general principle, I would say that if they increase our adaptiveness, our survivability—that is, our health—they are good. If they make us less adapted to survival, they are bad.
Today’s chief food culprit is not carbohydrates, the dietary mainstay of 25 million years—it’s refined carbohydrates, which did not exist until recently. Just what is a refined carb? It is a product of technology, a food that has been extracted from a “whole food,” leaving behind some of its most important nutrients. White flour (referred to as “wheat flour” on the packages of bread and cakes) is extracted from the whole grains of wheat (which yield “whole wheat flour”) ; sugars are extracted from canes, beets, and corn (the last of which yields high fructose corn syrup, a long bad story in itself). White rice is extracted from brown rice. These refined carbs appear in almost everything eaten today: bread (but not 100% whole grain bread), pasta (but not whole wheat pasta), cake, cookies, ice cream, most cold (and some hot) breakfast cereals, sauces, chips, candy and much more. Without the husks or germ or endosperm from the whole food, these refined carbs digest so rapidly that you would need to have the metabolism of a hyperactive teenager or run a marathon immediately after eating them in order to burn up the sudden burst of energy. Fruit juices (extracted and refined from whole fruit) are not much better than soda pop, a glass of apple juice consisting mainly of 100 calories of sugar-water from several apples instead of the sugar, fiber, and phytochemicals from one whole munched apple. Wine and beer, of course, are refined carbs (juices extracted from fruits and plants), but they offer compensatory benefits not obtainable from apple juice—and the report on red wine is consistently positive for health. Unused, all this energy stores as body fat for future use. (But if you eat this stuff again the next day, there IS no future use. You store more fat for a starvation period that never arrives.) Insulin resistance, diabetes, obesity and much more are the consequences. Whole foods release their energy slowly, giving you more time to use it up. And, of course, whole carbs have all sorts of trace minerals and fiber that our systems have evolved to need, that fill us up with fewer calories, and that today are believed to reduce the risk of cancer and other diseases.
All the meats we eat are also manufactures. Whereas hunter-gatherers caught wild animals that were low in body fat and muscular from running—tough and chewy by current standards—today’s animals are raised in factories, confined in pens, unable sometimes even to turn around. They are fed foods that they mostly never ate before, such as corn, to fatten them up quickly without muscle-toughening exercise (I won’t go into the drugs needed to enable their systems to tolerate this food). They are high in saturated fat (bad). That’s what all the “marbling” is about in prime meats, which fortunately have become hard to find.
Yet there is a fat that’s even worse for the arteries, heart, etc.: transfat, produced through hydrogenization of liquid fats. It’s present in almost every manufactured cake, bread, candy, cookie, coffee creamer and whatnot. (Though it’s not hard to avoid if you pay attention.) All that Crisco and Spry—pure transfat so cozily peddled to our mothers as “vegetable shortening” during our childhood—was just the beginning. Now it’s everywhere.
As for vegetables, hunter-gatherers would probably not recognize the ones we have today, which have been hybridized for a long time and now are further altered by genetic engineering. In the forty years during which I grew corn, for instance, the changes have been drastic, as anyone who bought seeds from Burpee’s and Gurney’s and Harris Seeds will recognize. Although there has been a bad side to some of this, my personal opinion here is that vegetables are better than ever and that we would find the veggies from our childhoods to be unappetizing and limited in variety. What the foragers searched all day to find (expending most of the calories from their last meal), we’d now regard as hog fodder. Vegetables and minimally processed grains are probably our best bet today for survival, supplemented with fish (hold the mercury!) and fowl (hold the antibiotics!).
In sum, the standard diet of industrialized nations is unsuited to our evolved constitutions. The sweet tooth that once goaded us to search for vegetation in the wilds now can be mega-gratified in five minutes by a brownie equal to a week’s worth of sugar from foraging.
Three leading scholar-writers in ecology and evolutionary biology have been shedding additional light on this core problem. In Guns, Germs, and Steel, Jared Diamond connects ecology and diet with the development of settled communities and civilization, explaining how the fortuities of environment and human intelligence are responsible for the foods we eat today, foods selected from myriad possibilities that were not as conducive to early modes of farming as the ones that emerged as winners. Although yams, manioc, and millet, for example, are still staples of non-Western diets, it is a handful of early-cultivated grains and beans that have become the primal fodder of the West, healthful at first but now degraded in the universally refined versions that suit the needs of food manufacturers more than the health needs of the general population. As these monocultured crops destroy the topsoil while requiring more and more pesticides, the knowledge of wild foods and natural products still retained by the world’s few remaining hunter-gatherer societies slowly disappears. Or as Diamond puts it, “This traditional knowledge gradually loses its value and becomes lost, until one arrives at modern supermarket shoppers who could not distinguish a wild grass from a wild pulse.”
The most powerful accounts I know of what has happened to the Western diet and its ecology can be found in the brilliant writings of Michael Pollan. In one of the four essays of his entrancing book, The Botany of Desire, Pollan provides background and meaning to the 19th century dissemination of appletree seeds by the legendary Johnny Appleseed. We learn that every seed in an apple (unlike every bean in a pod) will produce a different type of progeny with a different genetic character, so that grafting is the only way to produce new trees true to the occasionally sweet parent. The consequence, to quote one of Pollan’s informants, is that “A century ago there were several thousand different varieties of apples in commerce; now most of the apples we grow have the same five or six parents.” What results from this, of course, is a monoculture that breeds indigenous bugs with an evolved genetic makeup to thrive on these few varieties. Only constant use of pesticides can control them. Furthermore, to quote Pollan, “the domestication of the apple has gone too far, to the point where the species’ fitness for life in nature . . . has been dangerously compromised,” reduced to a “handful of genetically identical clones.”
In an even more striking series of articles that Pollan wrote for the New York Times, high-tech commercial domestication of foods is shown to produce consequences more dire. In his shocking article “Power Steer” Pollan describes his purchase of a newly born calf that he consigned to a standard feed lot while tracking its every stage as it was moved through the process leading to slaughter and packaging as supermarket meat. The horrors are manifold but the exaltation of corn feed by the combined power of the meat and agribusiness industries is especially egregious. The ruminative stomachs of cattle, which evolved to digest grass from grazing, are instead fed corn to fatten up bodies of meat that will be turned into steaks and chops in a fraction of the free-range time. Corn makes the cow’s rumen “unnaturally acidic, however, causing a kind of bovine heartburn, which in some cases can kill the animal but usually just makes it sick,” leading to a host of diseases, from ulcers to pneumonia and feedlot polio. The remedy, of course, is antibiotics, most of which in America end up in animal feed, producing antibiotic-resistant superbugs along the way.
Pollan, in “An Animal’s Place,” has a lot more to say about this as well as other forms of market-produced animal cruelty. Surveying the spectrum of philosophical views of animals, he writes: “Even vegans have a ‘serious clash of interests’ with other animals. The grain that the vegan eats is harvested with a combine that shreds field mice, while the farmer’s tractor crushes woodchucks in their burrows, and his pesticides drop songbirds from the sky. Steve Davis, an animal scientist at Oregon State University, has estimated that if America were to adopt a strictly vegetarian diet, the total number of animals killed every year would actually increase, as animal pasture gave way to row crops. Davis contends that if our goal is to kill as few animals as possible, then people should eat the largest possible animal that can live on the least intensively cultivated land: grass-fed beef for everybody. It would appear that killing animals is unavoidable no matter what we choose to eat.”
In his brief article about corn, “When a Crop Becomes King,” Pollan picks up on the feedlot corn diet to describe how “our entire food supply has undergone a process of ‘cornification’” through the efforts of giant agribusinesses such as Archer Daniels Midland, ConAgra, and Cargill. Not only are we being force-fed corn via the guts of factory raised animals, but high fructose corn syrup has become the most widely used sweetener, added to more products than the average consumer realizes, from the obvious soft drinks to every type of snack food and condiment. Of this immense ingestion of sugar, Pollan remarks,” It’s probably no coincidence that the wholesale switch to corn sweeteners in the 1980’s marks the beginning of the epidemic of obesity and Type 2 diabetes.” Moreover, corn requires more nitrogen-based fertilizers and pesticides than any other crop, as well as oil and natural gas to produce them, so the damage from corn extends to both humans and the environment (though the “environment” is ultimately us).
The subject of obesity and diabetes leads us to Gary Nabhan, whose two most recent books address these subjects directly. Why Some Like it Hot, the newer of them, has logical priority because it provides the theory whose practice had already been worked out in the earlier book, Coming Home to Eat. The theory, in a nutshell, is that the food needs of Homo sapiens are not just the product of their Paleolithic past but of the indigenous cultures that have tweaked their genes since that past. When members of these cultures leave their native habitats and migrate to other parts of the world, puzzling infirmities often manifest themselves along with the change in diet. Moreover, not even a migration is needed—a cultural change that produces a dietary change is a virtual migration that can be just as dire as a real one. In the United States the increasingly Westernized diet of Native Americans has produced the most extreme proliferation of diabetes. Nabhan, living in Arizona and with many Indian friends, has seen the consequences at close quarters. But as an ecologist, he also has an additional motive for addressing the refined carbohydrate diet that precipitated this epidemic: the extraordinary amount of energy—particularly fossil fuels—that is consumed to process and transport foods of all kinds, even those considered healthful, from far away places (like the Braeburne apples I buy imported from New Zealand). The cumulative force of these various motives led Nabhan to investigate the plausibility of eating locally grown whole foods. Tossing cans and bags of junk or refined foods from his larder into the trash he began to track down local farmers and backyard vegetable growers in southern Arizona, largely an older generation, who still grew and consumed indigenous crops. Not only did he begin to eat plants that most of us have never encountered as food, he organized a band of about 180 Native Americans and Anglos to walk several hundred miles across the Sonoran Desert of Arizona, subsisting mainly on indigenous plants and animals, with a bit of dietary help from friends along the route. Although largely symbolic, the aim of this walk was to show that a return to a local, healthful, diet was still possible.
But even Nabhan had to admit that getting most of his friends to eat this food in their normal daily lives was a hard sell. And to speak personally, apart from those mired in poverty and primitive conditions, the dream of a return to an indigenous diet seems highly implausible in a world of 6 billion people, many of whom have reached a stage of unprecedented comfort and affluence—while others starve.
Those of us who come to conferences, highly educated, mostly well off, living not far from a Trader Joe’s or a Whole Foods or even an upscale Safeway are in a privileged position to buy unrefined whole foods and maintain a healthful diet, though it’s a diet that can not by a long shot be considered local. But it’s hard to see how the intertwined dilemma of mass produced cheap refined foods--triggering widespread obesity plus diabetes--and enormous consumption of fossil fuels to process, package, and deliver them is going to be resolved in the near future.