How cooking turned humans into an invasive species

How did humans become the swarming, world-spanning species that we are today? A lot of reasons, sure, but one of them may very well have been the invention of cooking. This everyday scientific discipline changed the world - and may change it still more.

Food innovation is considered many things: a basic necessity, an art, an aesthetic accomplishment, or hipster foodie nonsense. What it is, and always has been, is a scientific innovation. The first person who realized that egg white, when whipped and baked, could be made into a hard shell-like substance that could be eaten, was a materials scientist. In this case, the contribution was small. But other scientific steps forward made major changes in human development.

How to Digest Food Outside Your Stomach

How many pounds of food did you eat today? Was it less than, roughly, twelve? Then you probably cooked a few things. (Even if you stayed away from all cooked food, the food you did eat was cultivated for tens of thousands of years in an effort to make it fit for humans.) Richard Wrangham, an anthropologist and biologist, calculated that Homo Erectus would have needed roughly that much food to survive. There wasn't always that much on offer. What made the difference? A bunch of hot sticks.

How cooking turned humans into an invasive speciesS

Cooking breaks down proteins, softens fruits and tubers, and causes the overall bulk of a piece of food to shrink. It essentially, does part of the digestion for us. And that saves energy. When Wrangham studied a python model of digestion - a common way to study the biological process of digestion - he discovered that the snake got more energy from cooked food than from raw food. This discovery corresponded with an early 'campsite' where wood of various different types was burned at ground level about 1.6 million years ago. The two discoveries together could indicate the reason for a profound change in human physiology and behavior.

The human gut, not needing to process as much food as it once did and not needing to process it as strenuously as it once did, shrank down. The brain, meanwhile, with its prodigious need for food (requiring nine times as much energy as muscle tissue) enlarged. The teeth and mouth shrank down. The cranium expanded.

And there was more time to use that cranium. Twelve pounds of food doesn't gather and digest itself. The fibrous fruit and leaves that chimpanzees eat take them a long while to chew and swallow, even with their larger mouths and massive teeth. Even if all the necessary food was on hand, humans would have had to be chewing, just chewing, for about six hours a day. Paired with gathering the food, nutrition would have taken up the vast majority of every human's waking hours. Add a little fire, and proto-humans turned from food gathering machines to a species with a big brain and time on its hands. That was a dangerous combination, and it lead to the swarming, invasive species we are today.

Learning to Love Sour and Bitter

What humans always do when they have time on their hands, is find a way to fill it. Ancient humans filled it in ways we still resort to today; traveling around, making new little humans, and wondering 'what would that taste like?' The first two generally drove the third. Heribert Watzke, a food scientist, believes that cooking greatly helped out with that third thing. Humans are so intrinsically bound up with cooked food, he believes, that they should stop calling themselves 'omnivores' and start calling themselves 'coctivores.' Humans are the only animal that, the world over, lives on cooked food.

It was coctivores that walked out of Africa, and onto every other continent. Not only was cooking, finding new things to cook, new scents and flavors, a constant exercise for the brain, it was a way to transform any food into something, well, at least edible. Cooking almost any meat, even fish in a hot climate, burned away the bugs most likely to kill people, letting humans be more adventurous with their diet in a foreign land. The process of cooking also helped the psychological adjustment that it took to digest food. Modern day humans will recoil from food that is too foreign to them. A new taste or smell might be repellent, but if it were incorporated into an old 'recipe,' it could slip by without the stomach rebelling.

How cooking turned humans into an invasive speciesS


Finally, according to Watzke, cooking helped overcome the two tastes most likely to dissuade humans from eating: sour and bitter. These tastes, originally, were designed to keep humans and other animals away from poisonous, spoiled, or rotting food. Plants took advantage of the tastes and used them to keep their leaves and fruits safe from all but select animals. But a well-cooked meal could include these new flavors. Few will bite directly into a lemon, but they'll bite into something flavored with lemon juice and lemon peel readily enough. Bitter greens aren't fun to eat, but flavor a stew perfectly well. Cooking expanded the reach of humans, both in the number of plants and animals that offered themselves up as food, and consequently in the total range of ground covered. Unlike animals, humans didn't need a steady diet of recognizable foods. They went to different environments and made their own.

How cooking turned humans into an invasive speciesS

Let's Get Agricultural

But the real test of an invasive species is whether or not it displaces other species in order to make a place for itself. In this, cooking most definitely helped. Not simply the cooking of a haunch of wildebeest over the fire, but the grain revolution. Although herders do transform the landscape dramatically, there have always been herds, and always been those that killed and fed on them. Grain fields were something else again. The earliest grains, all wheat grasses like einkorn, spelt, and emmer, could be harvested once and stored for the length of the rest of the year.

However grains were stored, they needed to be cooked before they could be consumed. Rice is an inedible pellet without cooking. Wheat is a handful of fibrous tufts, much of which are difficult to digest when raw. Even soaking it won't make it completely digestible. It takes the heat. The earliest breads were simple things, grains mashed up, mixed with water, and put on some stones with coals or ashes shoveled on top of the dough. Some grains were eaten simply warmed in water as a slurry or porridge. Whatever the form did, the heating denatured the long strands of protein within the grains.

Ultimately grain, whether raw or cooked, could provide for entire communities, all of whom stayed in one place. It could free up even more time, leaving certain members of those communities with no food-gathering tasks whatsoever. If cooking meat and tubers left each individual with time to explore, to find new places to live, new foods to eat, to have a bigger family, build a steady base and then expand - the cultivation and cooking of grains left entire sections of communities free to do the same. Humans were free to transform the landscape, build bases of power, have plenty of children, build technology that lead them to new horizons, and make their way into pretty much every available scrap of land on Earth. As long as they cooked.

Top Image: TWO
Frying Meat Image: Jan Harenburg

Lemon Image: André Karwath

Wheat Image: Go2anna
Via Scientific American, Ted Talks, Neuroanthropology, the Exploratorium.