Cooking is essential to our species. Some researchers believe it allowed our ancestors to free up extra calories needed for brain growth. The exact timing of this transition is unknown, but there is evidence to suggest it. People were cooking at least 50,000 years ago and up until 2 million years agoThis evidence comes from two fields: archaeology and biology.

What evidence does archaeology provide?

One archaeological evidence of cooking is cooked starch grains found in tartar (hardened dental plaque). Scientists have found this evidence in 50,000-year-old teeth.

But if we look at an earlier period, the evidence is less clear. Scientists often look for evidence that humans controlled fire. But the existence of controlled fire does not necessarily mean that food was being cooked: People may have used fire for warmth, for example, to make tools or to scare animals.

There is evidence of fire in all archaeological sources, but the problem lies in distinguishing whether it was a controlled fire or a naturally occurring fire, such as a forest fire.

We have a forest fire moving across the landscape, and we have hominids who can pick up a smoldering branch and use it, perhaps to make tools or cook food.
– says archaeologist-geochemist Bethan Linscott from Oxford University.

Linscott adds that one of the key things scientists look for when trying to prove firefighting patterns is the actual structure of the burn — perhaps stones arranged in a circle and then in the middle there’s a bit of ash, or phytoliths (silica structures left over from long-dead plants) or burned artifacts and other things.

Researchers have found these artifacts at many sites that existed before the emergence of Homo sapiens, meaning that earlier hominins also used fire:

• At Kesem Cave in Israel, a research team found evidence of a 300,000-year-old hearth alongside the remains of butchered animals.
• A 400,000-year-old hearth containing charred bones and flint used to make tools has been found buried in Suffolk, England.
• Researchers working at a site in Israel called Gesher Benot Yaakov have found convincing evidence of cooking 780,000 years ago: not only stone circles indicating a hearth, but also fish bones indicating that they were heated.
• Even earlier, ash in Vanderwerk Cave in South Africa led scientists to suspect that cooking took place 1 million years ago. The cave is so deep (about 30 meters deep) that the ash could not have formed a million years ago by a natural process.
• There is even evidence of controlled fire in Kenya 1.6 million years ago.

What clues does biology provide?

Biological evidence for when cooking began is available in the evolution of the human organism.

We as a species are different from every other species on Earth because we are biologically adapted to eat cooked food. So the question is: When did this happen?
– says Richard Wrangham, former professor of biological anthropology at Harvard University.

For example, in a study of people on a raw food diet, scientists found that participants tended to lose weight and a third of women stopped menstruating.

This may have started even before the emergence of modern humans, Wrangham says. Homo erectus was the first hominin to have body proportions that were less primate-like and more human-like, and some of these features suggest they may have been the first humans to prepare food.

One of the main differences between humans and our primate relatives is the size of our guts. Our guts are smaller than those of primates because cooking requires less digestion.

The last part of our intestines, our large intestine, is about two-thirds the size it would be if we were a chimpanzee, bonobo or gorilla.
Wrangham explained.

To accommodate a larger gut, non-human primates have a wide pelvis and broad ribs. Our human ancestors lost these features about 2 million years ago. So, we had to start preparing food earlier so that evolutionary processes could gradually respond and adjust our bodies accordingly.

Another event that happened around the same time (1.8 million years ago) was the largest reduction in the size of the chewing teeth in human evolutionary history. And again, this fits in very well with the idea that something suddenly changed in diet. In particular, food became easier to chew, softer.