Alone among the animals, we humans insist that our food be not only “good to eat”—tasty, safe, and nutritious—but also, in the words of Claude Lévi-Strauss, “good to think,” for among all the many other things we eat, we also eat ideas. Animal sacrifice has been a way to make animal flesh “good to think”—to help people feel better about killing, cooking, and eating animals, which has never been anything less than a momentous, spiritually freighted, and deeply ambivalent occasion. That might explain why, whether in Homer or Leviticus, the work of slaughter, butchery, and cooking all had to be performed by a priest; these were all equally solemn operations. Nowadays, we think of sacrifice as a primitive rite, and snicker at the underlying rationalizations, but the cultures that practiced such rituals before eating were at least acknowledging that something important was going on, something that demanded their full attention. Just because we no longer pay that kind of attention when we eat meat doesn’t mean that something momentous—in fact, a kind of sacrifice—hasn’t taken place. You have to wonder, who is really the more “primitive” character here? In our failure to attend to the processes that put meat on our plates, we moderns eat more like the animals than the ancients did.
This points to something else ritual sacrifice did for people: It drew sharp lines of distinction between humans and other animals on the one side, and between humans and the gods on the other. Other animals don’t clothe their killing or eating in ritual; nor do they cook their food over fires they control. When people participate in a ritual sacrifice, they’re situating themselves in the cosmos at a precise point halfway between the gods, whose power over them they acknowledge by making the sacred offering, and the animals, over whom the ceremonial killing demonstrates their own godlike powers. The recipe for the ritual tells us exactly where we stand.
One way to approach cooking of any kind is as a secular and somewhat faded version of the same operation, helping us to locate ourselves in nature and deal with our ambivalence about eating other beings. Like fire itself, which destroys what photosynthesis has created, all cooking begins with small or large acts of destruction: killing, cutting, chopping, mashing. In that sense, a sacrifice is at its very heart. But cooking also helps put Emerson’s “graceful distance of miles”—or time, or smoke, or seasoning, or chopping, or sauce—between the eaters and the eaten, its various transformations helping us to forget, or suppress, the violence of the underlying transaction. At the same time, the wonderful refining alchemies of the kitchen demonstrate how far we have come as a species, affirming that we have indeed lifted ourselves out of nature red in tooth and claw, achieved a kind of transcendence. Cooking sets us apart, helps us to mark and patrol the borders between ourselves and nature’s other creatures—none of which can cook.
“My definition of Man is a ‘Cooking Animal,’” James Boswell wrote. “The beasts have memory, judgment, and all the faculties and passions of our mind, in a certain degree, but no beast is a cook.” Boswell was not alone in regarding cooking as a faculty that defines us as human. According to Lévi-Strauss, the distinction between “the raw” and “the cooked” has served many cultures as the great trope for the difference between animals and people. In The Raw and the Cooked, he wrote, “Not only does cooking mark the transition from nature to culture, but through it and by means of it, the human state can be defined with all its attributes.” Cooking transforms nature and, by doing so, elevates us above that state, making us human.
If the human enterprise involves transforming the raw of nature into the cooked of culture, the different techniques we’ve devised for achieving this transformation each embody a different stance toward both nature on the one side and culture on the other. After studying the foodways of hundreds of peoples around the world, Lévi-Strauss (who apparently never saw a dualism he didn’t like) distinguished two basic methods for turning the stuff of nature into something that is not only more tasty and digestible but more human (i.e., good to think) as well: cooking directly over a fire and cooking in a pot with liquid.
To barbecue or to braise? To roast or to boil? That, apparently, is the question, and much—about who we think we are—depends on the answer. Compared with cooking over a fire, braising or stewing implies a more civilized approach to the transformation of nature. The braise or boil, since it cooks meat all the way through, achieves a more complete transcendence of the animal, and perhaps the animal in us, than does grilling over a fire, which leaves its object partly or entirely intact, and often leaves a trace of blood—a visible reminder, in other words, that this is a formerly living creature we’re feasting on. This lingering hint of savagery isn’t necessarily a strike against fire cooking, however. To the contrary, some believe a bloody slab of beefsteak augments the power of the eater. “Whoever partakes of it,” Roland Barthes wrote in Mythologies, “assimilates a bull-like strength.” By comparison, the braise or stew—and particularly the braise or stew of meat that’s been cut into geometric cubes and rendered tender by long hours in the pot—represents a deeper sublimation, or forgetting, of the brutal reality of this particular transaction among species.
Certainly this kind of forgetting has its advantages, especially in everyday life, where cooking in pots is the norm. Who wants to be confronted with existential questions of life and death and human identity on a daily basis? And yet there are times when that is exactly what we’re looking for, when we want to be reminded, if only a little, of what’s really going on just beneath the thin crust of civilization. This is, perhaps, the same impulse that compels some people to endure the discomforts of sleeping out in the woods, or to go to the unnecessary lengths of hunting their own meat or growing their own tomatoes. All these activities are forms of adult play that also serve as ceremonial acts of remembering—who we are, where we came from, how nature works. (And, perhaps, of a time when men were still indispensable.) Cooking meat over a fire—whether a few steaks thrown on the backyard barbecue or, more spectacularly, a whole animal roasted all night over a wood fire—is one of the most stirring of those ritual acts, usually performed outdoors, on special occasions, in public, and by men. And what, exactly, does such cooking commemorate? No doubt many things, including male power (for isn’t the triumph of the hunt at least implied?) and ritual sacrifice (for this is cooking-as-performance, exerting the kind of gravitational force that draws people out of the house to watch). But I suspect that, as much as anything else, grilling meat over a fire today commemorates the transformative power of cooking itself, which never appears so bright or explicit as when wood and fire and flesh are brought together under that aromatic empire of smoke.
II.
Cambridge, Massachusetts
“Homo sapiens is the only animal that …”
How many flattering clauses have philosophers tacked on to that cherished construction, only to watch them eventually crumble? One by one, the faculties on which we thought we could stake the flag of our specialness science has shown belong to other animals as well. Suffering? Reason? Language? Counting? Laughter? Self-consciousness? All have been proposed as human monopolies, and all have fallen before science’s deepening understanding of the animal brain and behavior. James Boswell’s nomination of cooking as the defining human ability seems more durable than most, though perhaps an even sturdier candidate would be this: “Humans are the only species that feels compelled to identify faculties that it alone possesses.”
But here’s why cooking may stand a better-than-average chance of surviving this silly game: Only the control of fire and consequent invention of cooking can explain the evolution of brains big and self-conscious enough to construct sentences like “Homo sapiens is the only species that …”
; That at least is the import of “the cooking hypothesis,” a recent contribution to evolutionary theory that throws a wonderfully ironic wrench into the scaffold of our self-regard. Cooking, according to the hypothesis, is not merely a metaphor for the creation of culture, as Lévi-Strauss proposed; it is its evolutionary prerequisite and biological foundation. Had our protohuman ancestors not seized control of fire and used it to cook their food, they would never have evolved into Homo sapiens. We think of cooking as a cultural innovation that lifts us up out of nature, a manifestation of human transcendence. But the reality is much more interesting: Cooking is by now baked into our biology (as it were), something that we have no choice but to do, if we are to feed our big, energy-guzzling brains. For our species, cooking is not a turn away from nature—it is our nature, by now as obligatory as nest building is for the birds.
I first encountered the cooking hypothesis in a 1999 article in the journal Current Anthropology titled “The Raw and the Stolen: Cooking and the Ecology of Human Origins” by Richard Wrangham, a Harvard anthropologist and primatologist, and four of his colleagues. Wrangham subsequently fleshed out the theory in a fascinating 2009 book, Catching Fire: How Cooking Made Us Human. Soon after it came out, we began corresponding by e-mail, and eventually we had the opportunity to meet, over a lunch (of raw salads) at the Harvard Faculty Club.
The hypothesis is an attempt to account for the dramatic change in primate physiology that occurred in Africa between 1.9 and 1.8 million years ago, with the emergence of Homo erectus, our evolutionary predecessor. Compared to the apelike habilines from which it evolved, Homo erectus had a smaller jaw, smaller teeth, a smaller gut—and a considerably larger brain. Standing upright and living on the ground, Homo erectus is the first primate to bear a stronger resemblance to humans than apes.
Anthropologists have long theorized that the advent of meat eating could account for the growth in the size of the primate brain, since the flesh of animals contains more energy than plant matter. But as Wrangham points out, the alimentary and digestive apparatus of Homo erectus is poorly adapted to a diet of raw meat, and even more poorly adapted to the raw plant foods that would still have been an important part of its diet, since a primate cannot live on meat alone. The chewing and digestion of raw food of any kind requires a big gut and big strong jaws and teeth—all tools that our ancestors had lost right around the time they acquired their bigger brains.
The control of fire and discovery of cooking best explain both these developments, Wrangham contends. Cooking renders food much easier to chew and digest, obviating the need for a strong jaw or substantial gut. Digestion is a metabolically expensive operation, consuming in many species as much energy as locomotion. The body must work especially hard to process raw foodstuffs, in which the strong muscle fibers and sinews in meat and the tough cellulose in the cell walls of plants must be broken down before the small intestines can absorb the amino acids, lipids, and sugars locked up in these foods. Cooking in effect takes much of the work of digestion outside the body, using the energy of fire in (partial) place of the energy of our bodies to break down complex carbohydrates and render proteins more digestible.
Applying the heat of a fire to food transforms it in several ways—some of them chemical, others physical—but all with the same result: making more energy available to the creatures that eat it. Exposure to heat “denatures” proteins—unfolding their origami structures in such a way as to expose more surface area to the action of our digestive enzymes. Given enough time, heat also turns the tough collagen in the connective tissues of muscle into a soft, readily digestible jelly. In the case of plant foods, fire “gelatinizes” starches, the first step in breaking them down into simple sugars. Many plants that are toxic eaten raw, including tubers such as cassava, are rendered harmless as well as more nutritious by heat. Other foodstuffs the cook fire purifies, by killing bacteria and parasites; it also retards spoilage in meat. Cooking improves texture and taste as well, making many foods more tender, and others sweeter or less bitter. Though which comes first—an inborn taste for cooked food or nearly two million years of familiarity with it—is hard to say.
True, cooking can have some negative, seemingly maladaptive, effects, too. High heat produces carcinogenic compounds in some foods, but the danger of these toxins is outweighed by the sheer increase in energy that cooking makes available to us—and life is at bottom a competition for energy. Taken as a whole, cooking opened up vast new horizons of edibility for our ancestors, giving them an important competitive edge over other species and, not insignificantly, leaving us more time to do things besides looking for food and chewing it.
This is no small matter. Based on observations of other primates of comparable size, Wrangham estimates that before our ancestors learned to cook their food they would have had to devote fully half their waking hours simply to the act of chewing it. Chimps like to eat meat and can hunt, but they have to spend so much of their time in mastication that only about eighteen minutes are left each day for hunting, not nearly enough to make meat a staple of their diets. Wrangham estimates that cooking our food gives our species an extra four hours a day. (This happens to be roughly the same amount of time we now devote to watching television.)
“Voracious animals … both feed continually and as incessantly eliminate,” the Roman physician Galen of Pergamum pointed out, “leading a life truly inimical to philosophy and music, as Plato has said, whereas nobler animals neither eat nor eliminate continually.” By freeing us from the need to feed constantly, cooking ennobled us, putting us on the path to philosophy and music. All those myths that trace the godlike powers of the human mind to a divine gift or theft of fire may contain a larger truth than we ever realized.
Yet having crossed this Rubicon, trading away a big gut for a big brain, we can’t go back, as much as raw-food faddists would like to. Wrangham cites several studies indicating that in fact humans don’t do well on raw food: They can’t maintain their body weight, and half of the women on a raw-food regimen stop menstruating. Devotees of raw food rely heavily on juicers and blenders, because otherwise they would have to spend as much time chewing as the chimps do. It is difficult, if not impossible, to extract sufficient energy from unprocessed plant matter to power a body with such a big, hungry brain. (Our brains constitute only 2.5 percent of our weight yet consume 20 percent of our energy when we’re resting.) By now, “humans are adapted to eating cooked food in the same essential way as cows are adapted to eating grass,” Wrangham says. “We are tied to our adapted diet of cooked food, and the results pervade our lives, from our bodies to our minds. We humans are the cooking apes, the creatures of the flame.”
How do we know if the cooking hypothesis is true? We don’t. It’s just a hypothesis, and not an easy one to prove. The fossil evidence that humans were cooking when Homo erectus walked the earth is not yet there, though it has recently gotten stronger. When Wrangham first published, the oldest known fossil remains put the date for controlled fire at around 790,000 B.C., but Wrangham’s hypothesis suggests cooking must have begun at least a million years earlier. In his defense, Wrangham pointed out that evidence of fires that old would be unlikely to survive. Also, cooking meat doesn’t necessarily leave behind charred bones. But recently archaeologists found a hearth in a cave in South Africa that pushed the likely date for cooking back considerably further,* to one million years B.C., and the hunt for even older cook fires is on.
So far at least, Wrangham’s most convincing arguments are deductive ones. Some new factor of natural selection changed the course of primate evolution about two million years ago, expanding the brain and shrinking the gut; the most plausible candidate for this new sel
ective pressure is the availability of a new, higher-quality diet. Meat by itself could not have supplied that diet. Primates, unlike dogs, don’t digest raw flesh efficiently enough to thrive on it. The only diet that could have yielded such a dramatic increase in energy is cooked food. “We are,” he concludes, “cooks more than carnivores.”
To demonstrate how the advent of cooking could have supplied a caloric boon sufficient to change the course of our evolution, Wrangham cites several animal-feeding studies comparing raw and cooked or otherwise processed food. When researchers switch a python’s diet from raw beef to cooked hamburger, the snake’s “metabolic cost of digestion” is reduced by nearly 25 percent, leaving the animal that much more energy to put to other purposes. Mice grow faster and fatter on a diet of cooked meat than on a diet of the same meat raw.* This might explain why our pets tend toward obesity, since most modern pet food is cooked.
It would seem that all calories are not created equal, or, as a proverb quoted by Jean Anthelme Brillat-Savarin in The Physiology of Taste puts it, “A man does not live on what he eats, an old proverb says, but on what he digests.” Cooking allows us to digest more of what we eat, and to use less energy doing it.† What is curious is that animals seem instinctively to know this: Given the choice, many animals will opt for cooked food over raw. This shouldn’t surprise us: “Cooked food is better than raw,” Wrangham says, “because life is mostly concerned with energy”—and cooked food yields more energy.