We are the creatures of flame: interview with Richard WRANGHAM 

Rarely do we ask ourselves what our life would be like without fire. We may not notice it with the naked eye, but it is there, in our basement, in the engine of our car or in the power grid. We made it our own until we completely forgot what we left behind thanks to fire: nothing but a life of cold, dark and dangerous nights. And it gave us the gift of something that makes us human: cooked food. 

The change in food consumption marked our evolution and that is precisely what we’re talking about with Richard Wrangham, professor, lecturer and researcher of Biological Anthropology at Harvard University and author of the book Catching Fire: How Cooking Made Us Human 

In Africa two million years ago, the genus Homo, i.e., the “human race”, emerged. They differed from their ancestors, the Australopithecus apes, in a number of physical conditions: these ancestors of Homo were twice as heavy, had brains almost twice as large, and smaller mouths, teeth and abdomens. They were also very adept at climbing easily, another trait that Homo did not retain. In the cooking hypothesis developed by Wrangham in his book published by Profile Books, the key to these differences lies in the kitchen. 

“The ability to control fire and cook food explains these changes: compared to the australopithecines, Homo had more digestible food and could afford to sleep on the ground when they were protected by fire”, says the specialist.

The kitchen has many advantages. Some of them are the elimination of bacteria, reduction of toxins, and the improvement of flavours and texture. However, “the most important advantage of cooking is that we get more calories from our food when we eat it cooked than when we eat it raw”, explains the specialist. 

“When people restrict their diet to raw foods, even if they put their food through a food processor, they have difficulty maintaining their body weight”, he adds. Humans are unique among animals in having adapted to eating cooked food. The advantage is that we can have relatively small intestines, which allows us to use our energy reserves for other organs such as the brain. The downside is that we are specialised: we can no longer thrive on raw foods. 

— But in ancient times we only ate fresh vegetables and raw meat, why couldn’t we live today without cooked food? 

— “The problem for humans is two-fold. First, our digestive systems have adapted so well to eating our food cooked that we can no longer digest raw food very well. But second, even if we had retained the digestive system found in apes such as chimpanzees and gorillas, a raw diet would be incompatible with having brains as big as ours”. 

The human brain weighs about 2.5 percent of our body; however, it consumes 25 percent of our energy. It is, to put it bluntly, an expensive organ to maintain. “It requires very high amounts of energy 24 hours a day. It was only after our ancestors began to cook, and therefore had more digestive energy, that natural selection could favour an increase in the size of human brains”. 

Today, studies of raw food eaters show that, on average, women who eat raw foods tend to consume so few calories that they stop ovulating, so they would not be able to have babies. In nature, the difficulty would be much worse and would mean that humans would not be able to maintain their populations without cooking their food. 

— What other changes did our ancestors experience due to cooked food? 

— “One very big change was a reduction in the amount of time spent eating. If we ate raw wild foods, we would be chewing about 8 hours a day, and then we would have to spend more time resting to allow digestion to occur! But thanks to cooked food, we only spend about an hour a day chewing our food.” 

This reduction in the amount of time spent chewing meant that humans were free to do many other things. Not only gathering firewood and cooking, but also hunting difficult prey or making tools, among other activities. 

—Let’s talk about what’s to come. 

— “In recent centuries the diets of many people in the world have become more digestible thanks to changes in farming systems and food preparation. Overall, we can expect our food to become more and more easily digestible, which might mean that we have more problems with our teeth and jaws because they are not used sufficiently to make them develop as they should”. 

—What about cuisine and culture? How are they linked?  

— “Cuisine is a recent phenomenon, in evolutionary terms, and greatly enriches cultural life. People are much more flexible in developing their food preferences up to about 8 years old than they are in adolescence and adulthood. This means that as adults, we tend to cling to the cuisines we grew up with as children. Why we should be so stuck on our childhood cuisines is an interesting puzzle”. 

The way we eat shapes our lives. Today, our food systems are damaged and generate problems of availability, access, nutrition and stability. 

— “We  have been living in recent decades with an amazingly successful and relaxed relationship between global food production and global food needs, thanks to the green revolution and global trade. We need to find ways to make that kind of relationship sustainable.

Most importantly, we should avoid turning the entire planet into a giant system for producing human food because if agricultural production covers the Earth, we will lose not only the biodiversity that means so much to us, but also the flexibility to respond to the inevitable crises.”