Catching Fire: How Cooking Made Us Human
When we think about what makes us human, we usually think about our upright stance, our large brains, and our ability to use tools and language. Those aspects of humanity are easy to see and leave durable traces, such as million-year-old stone hand axes from Africa and ten thousand year old cuneiform tablets from Mesopotamia. Yet it may be something more humble and difficult to spot that really set us on the evolutionary path to where we are now. According to anthropologist and primatologist Richard Wrangham, cooking is likely the one thing above all others that made us human.
It is possible to envision how it got started. Modern primates are known to throw rocks around, perhaps in conflict or play, and perhaps one of our tree-dwelling ancestors noticed that crashing certain types of rocks together would send off sparks that could catch grass on fire. Tending such a fire would certainly have been within the capability of our distant ancestors, as it is for primates today. Some can even start a fire if given matches. Fire would have been an excellent deterrent against predators, and would have made living on the ground and out of the trees safer. This would have been important during times of climate change when forest was replaced with savannah. It was probably not long before someone noticed that food dropped in the fire for a while tasted better, was easier to eat, and felt more satisfying. The rest is evolutionary history.
These days there a lot of theories going around about what humans are supposed to eat. Two of the most popular (and extreme) are the raw food movement and the (supposedly) paleolithic diet. Wrangham easily demolishes the former by pointing out that cooked food is far more digestible than raw food, and that our digestive systems are clearly adapted to easily digestible food. Compared to other primates, our teeth are small, our jaws are weak, and our intestines are small. We are simply not physically capable of chewing and digesting wild raw foods as other primates do. The proof of this comes from studies of raw food enthusiasts, which show that about half of the women stop menstruating, even on a diet much richer than you would actually find in the wild. No species can survive with half of its females infertile.
The other diet fad Wrangham addresses is the “paleolithic” diet, which emphasizes meat, meat, and more meat, and avoids carbs as much as possible. People on this sort of diet (as on the raw food diet) find that they are always hungry. This is something the native peoples of North America could have told them about. They call it “rabbit hunger” and scientists call it “ketosis.” A diet heavy in lean meat causes protein poisoning that damages the kidneys and liver, causes intense hunger, and eventually leads to death, as many early explorers discovered the hard way. In fact we know that the maximum safe level of protein intake is half of all calories, so at least half our diet must consist of carbohydrates and fat. Fat, whether animal or vegetable, is a rare commodity in the tropics where we evolved, so that means our ancestors ate at least half of their diet as carbohydrates. So much for that theory.
Although cooking can seem like a chore to some of us, it actually liberated us from the much more onerous chore of chewing and digesting raw food. Primates spend a good deal of their day just chewing tough raw foods like leaves and wild fruits (which are not as soft and plump as agricultural fruits). Furthermore, because their food was so low in digestible calories, they had to eat almost constantly throughout the day. Chimpanzees only get about 20 minutes off between meals, which doesn’t leave much time for doing anything constructive. Our ancestors, on the other hand, could get far more calories from cooked food, and so had hours of free time to go gather choice foods, such as carbohydrate-rich roots, honey, and of course, animals. All that travelling, hunting, digging, and carrying would have encouraged our bipedal stance and our ability to walk and run with our hands free. (See more on that here.) The more rich cooked food we ate, the less energy was devoted to chewing and digestion and the more could be devoted to our growing brains. And so, here we are.
I posted before about the downside of all this: due to the size difference between males and females, a male can force a female to cook for him in exchange for occasional meat and, more importantly, protection from other males who would take the cooked food by force. Wrangham calls it a protection racket, which sounds about right. This is the system that prevails in every culture ever studied, past or present, rich or poor, pastoral or agricultural, “primitive” or “civilized,” patriarchal or (otherwise) egalitarian. It may be dressed up with romance and marriage rituals, but the cooking compact is at its foundation an unequal bargain. What really impresses me is that women still know it. Our sense of equal worth has not been blunted by two million years of involuntary servitude. Anthropologists have recorded the complaints of women from diverse cultures saying exactly the same thing: “Here I am, slaving over the fire/stove while my husband sits around doing nothing.” The ability to cook has done wonderful things for our species, but perhaps it is the utterly unquenchable desire for equality and freedom that is the best human characteristic.