Around 1.9 million years ago some major changes occurred in hominin biology. Compared with its ancestors, Homo erectus had very small teeth, a small body and a much larger brain. According to a controversial hypothesis put forward by primatologist Richard Wrangham, these changes were driven by cooked food. In fact, Wrangham believes that cooking drove our lineage’s divergence from more ape-like ancestors and that the bodies of Homo sapiens couldn’t exist without cooked food.

Our small teeth and jaws tell a similar story. They are too small for the task of grinding down large quantities of tough raw food. Compared with earlier hominins such as Homo habilis, modern humans, Neanderthals and Homo erectus all have small teeth relative to their body size. To Wrangham, these morphological features are adaptations to cooking that arose around 1.9 million years ago.

There are, however, flaws in the cooking hypothesis. Many of the adaptations attributed to cooked food such as large brains could have arisen through an increase in raw meat consumption. The disconnect in time between the biological evidence and the control of fire is another stumbling block.

However, the earliest firm evidence that our own species was cooking dates back just 20,000 years, when the first pots were made in China. The scorch marks and soot on their outer surfaces point to their use as cooking utensils. But all in all, archaeological evidence doesn’t paint a clear picture.

The Neanderthals who evolved from Homo erectus some 250,000 years ago certainly created fires, as hearths have been found at many Neanderthal sites, some containing burnt bones. We also know from analysing their dental plaque that Neanderthals spiced up their diets with herbs. But we don’t know whether they habitually cooked their food.

Traces of ash found in the Wonderwerk cave in South Africa suggest that hominins were controlling fire at least 1 million years ago, the time of our direct ancestor Homo erectus. Burnt bone fragments also found at this site suggest that Homo erectus was cooking meat. However, the oldest remains of obvious hearths are just 400,000 years old.