Cooked food features into the diet of every human culture. Indeed, some anthropologists such as Richard Wrangham at Harvard have argued that the acquisition of cooking was the catalyst that allowed for the development of many of the unique physical and behavioral adaptations of the hominid line since Homo erectus such as smaller molars and jaws, a larger body size with less sexual dimorphism, a larger brain, and a further focus on bipedality with a reduction in the upper body features that allowed earlier hominids to more easily climb and move about in trees (Wrangham et al. 1999; Wrangham 2009).
Cooked food has many advantages over raw food. First, cooked plant food is softer and thus easier to both chew and digest. Cooking meat also kills many of the pathogens. There are also many foods that can’t be consumed by humans unless they are processed and cooked, such as many tubers that are rich in starch. Wrangham has argued that cooking was a form of ‘pre-digestion’ that allowed the digestive system to expend less energy in digestion. Cooking would have allowed people to exploit many new kinds of resources, as well as allow them to expand into new habitats, which may have contributed to the colonization by Homo erectus of most of Eurasia. Some other interesting recent evidence is that in most cases, the great apes – albeit captive apes that are provisioned in a sanctuary and regularly receive some cooked food – also appear to prefer cooked food over raw food as well, suggesting that paleolithic hominids would also have preferred cooked food if when it was discovered (Wobber et al. 2008).
The argument that cooking fundamentally changed the body and behavior of the human lineage is known as the cooking hypothesis. It’s one of the contenders attempting to account for many of the unique derived features in the human lineage. Among others are the savanna hypothesis and the meat hunting hypothesis, that argued that these features were adaptations that came from an increased focus on a open area savanna habitat or from an increased dietary commitment to hunting, respectively.
One problem that has prevented a more widespread acceptance of the cooking hypothesis is that the most oldest evidence for controlled fire has only dated back to about 400,000 years ago at Qesem Cave in Palestine, which puts it in the time of the archaic Homo sapiens and the Neanderthals rather than Homo erectus. Archaeologists have found evidence of fire associated with human sites from earlier times in China, Kenya, and France, going back over 1.5 million years. However, these have been from open air sites, which makes us unable to rule out that they were the result of wildfires.
A new study just published in the Proceedings of the National Academy of Sciences, however, has presented what is as yet the earliest evidence of controlled fire (Berna et al. 2012). The site is Wonderwerk Cave in Northern Cape province, South Africa. Using micromorphological analysis and Fourier transform infrared microspectroscopy (neither of which I’m equipped to explain), they have found ashed plant material and charred bones and teeth at the same layer as several Acheulean hand axes and other lithic materials that date to around 1.0 million years ago.
Using their techniques, they were also able to estimate that the remains were heated to over 400o C, but at no higher than 700o C. This suggests that a light fuel source was used, such as grass, leaves, and brush rather than heavier fuel sources such as large pieces of wood that burn at too high of a temperature. The site was located far enough into the cave to rule out wildfires, and they also point out that there was no evidence of bat guano in the relevant layers, which has been known to self-ignite within caves.
This is interesting evidence that extends controlled fire and cooking back far into the lower paleolithic. It does not show that cooking was present at the speciation event around 1.8 or 1.9 million years ago that produced H. erectus, which is what Wrangham’s cooking hypothesis relies upon, but it does show that Acheulian hominids were capable of controlling and cooking with fire.
* * *
Berna, F., et al. 2012. Microstratigraphic Evidence of In Situ Fire in the Acheulean Strata of Wonderwerk Cave, Northern Cape Province, South Africa. Proceedings of the National Academy of Sciences, In Press. http://www.pnas.org/content/early/2012/03/27/1117620109.full.pdf+html
Roebroeks, W. & Villa, P. 2011. On the Earliest Evidence for Habitual Use of Fire in Europe. Proceedings of the National Academy of Sciences 108, 5209-5214. http://www.pnas.org/content/108/13/5209.full – Open Access
Wobber V, Hare B, & Wrangham R. 2008. Great apes prefer cooked food. Journal of Human Evolution 55, 340–348. http://evolutionaryanthropology.duke.edu/uploads/assets/Wobber%20et%20al,%202008.pdf
Wrangham, R. 1999. Catching Fire: How Cooking Made Us Human. Basic Books. http://www.amazon.com/Catching-Fire-Cooking-Made-Human/dp/0465013627
Wrangham, R., Holland Jones, J., Laden, G., Pilbeam, D., & Conklin-Brittain, N.L. 1999. The Raw and the Stolen: Cooking and the Ecology of Human Origins. Current Anthropolgy 40, 567-594. http://www.gregladen.com/wordpress/wp-content/pdf/WranghamEtAl.pdf