The Cooking Ape Hypothesis: How Humans Became Intelligent

steak on campfire cooking

Chimpanzees are our closest cousins, yet we differ from them in many aspects – the main one being our brain capacity. Have you ever wondered how humans diverged from apes and how we attained our superior intelligence? It might be hard to believe, but the reason could be as simple as the act of cooking. Known as the ‘Cooking Ape hypothesis’ (developed by British primatologist Richard Wrangham), many scientists today agree that cooking was the catalyst for the development of our intelligence.

Cooking and the Evolution of Human Intelligence

Cooking is essentially the only universal behavior that is unique to human beings. Whether carnivorous, herbivorous or somewhere in between, every other animal on the planet eats their food raw. We can even go so far as to say that the consumption of cooked food is responsible for humans evolving our unmatched intellectual capacity. This is especially apparent when we compare ourselves to our Simian (primate) counterparts in the context of cooking, in what is referred to as the ‘Cooking Ape Hypothesis’.



Cooking and the Brain

It may be hard to believe that cooked food is actually linked to our intelligence. It does not mean that if you consume more cooked food, you will become smarter, although this would be pretty neat. Rather, from prehistoric hominids to present-day humans, the emergence of cooked food is strongly intertwined with the evolution of our intelligence.

Our brain is one of the highest energy-consuming organs, taking up 20% of our body’s energy requirements. The problem with raw food is that it does not give us enough calories to sustain the activities of our higher-capacity brains. This is where cooked food comes in as a solution. The process of cooking food breaks it down, making it easier for digestion and absorption by our digestive system. Not only do we gain more energy from the more effective absorption of nutrients from cooked food, but the energy saved in digesting a softer diet also boosts our calorie intake further1.

Biological Adaptations to Eating Cooked Food

Unlike other mammals’ biological makeup, our teeth and digestive tract are better suited to digesting cooked food. Firstly, human intestines are shorter and smaller compared to those of other mammals2. Raw food requires a longer digestion time since the nutrients are not partially broken down, unlike when food is cooked. With a smaller digestive tract, it is a given that our body has to adapt to a lower-fiber diet due to a shorter digestive pathway available to digest our food.  While we can eat raw leaves in the occasional salad, we cannot survive on it solely, unlike chimpanzees who feed off these leaves daily.

Digestive tract anatomy across various mammals. In comparison, the human digestive tract is the shortest (Source)

Secondly, humans have very small teeth; we have the smallest teeth of any primate relative to our body size3. This has evolved over time to account for a softer diet. Having such small molars also means we cannot chew on tough foods continuously, compared to other primates with massive grinding machinery.

Fun fact: Great apes, despite their size, have extremely small baculum (penis bone)

Comparisons of molar sizes with our primate counterparts and early hominids (Source)

Due to the way our human body has evolved and adapted to a soft diet, we also spend less time eating compared to other animals. This gives us more time to go about other activities throughout the day. Combined with the evolutionary factors outlined, there is strong evidence that shows our ancestral dependence on cooked food over millions of years (even pre-Homo sapiens!)

Cooked Food versus Raw Food

What about the Inuits? Don’t they consume raw seals? Yes, they partly do – but only as a delicacy. Most of our favorite raw dishes, like sashimi, only make up a small part of our diet. For the most part, our body relies on cooked food to function. In fact, humans are unable to survive on a raw food diet alone due to our biological makeup and adaptations. Consuming only raw food as a staple causes body mass index (BMI) to quickly decrease to dangerously low levels, with other health concerns such as amenorrhea in women4.

As an aside, Wrangham’s investigations found that the longest recorded case of a human surviving on raw food was a woman named Helena Valero who was held captive by a Brazilian Indian tribe and escaped to the forest. By her own account, she was able to survive 6 months eating only raw bananas5.

Fire – The Cooking Ape’s Weakness

Despite the encouraging evidence in support of the theory, Richard Wrangham’s Cooking Ape hypothesis is just that – a hypothesis – and it comes with loopholes as well. In this case, one major issue with Wrangham’s hypothesis is the origin of the use of fire.

Earliest Use of Fire In Cooking?

How far back do we have substantial evidence of the use of fire for cooking by prehistoric humans? If Wrangham was right, somewhere along the prehistoric timeline of early hominids – such as during the Homo erectus era – there should be evidence of the use of fire for cooking to substantiate the claim that our anatomy became more biologically adapted to eating cooked food.

Using special dating techniques, the earliest evidence of a cooking fire was found to be used by Homo erectus around 400,000 years ago6, but this does not fully cover the era that the ‘Cooking Ape’ hypothesis is set in. The biological adaptations for consuming cooked food date back to 2 million years ago, around the time when Homo erectus first emerged. Fossil records show that their anatomical adaptations mirrored that of modern-day humans (Homo sapiens)7.

Many of Wrangham’s point at the lack of evidence of fire used for cooking at the time. Since the biological adaptations occurred without evidence of cooked food, critics suggest that the evolution of a ‘cooked-food digestive system’ might not actually be driven by cooked food!

Wrangham counterargues that the features of our anatomy today, like the smaller digestive tract and molars, can only be attributed to the consumption of cooked food and that there is no other viable explanation. Additionally, if one were to go back more than a million years, the evidence for the use of fire would deteriorate after exposure to the elements.

In a Nutshell

The Cooking Ape hypothesis is favored by many scientists but is also regarded to be ambiguous by some critics. Granted, we are presently unable to prove that our early prehistoric hominid ancestors did use fire for cooking food. However, the bulk of evidence in the anatomy changes and differences in humans compared to the fossils of those hominid ancestors alone seems to be convincing enough to justify the wide acceptance of this hypothesis.

We might never know whether eating cooked food gave rise to our relatively higher cognitive intelligence, but we can sure be glad that humans have evolved this way!

This article was written by Jovi Wong via Write For Us.



Reference

  1. Carmody, R. N., Weintraub, G. S., & Wrangham, R. W. (2011). Energetic consequences of thermal and nonthermal food processing. Proceedings of the National Academy of Sciences108(48), 19199–19203. https://doi.org/10.1073/pnas.1112128108
  2. David J Chivers, Claude Marcel Hladik (1980). Morphology of the gastrointestinal tract in primates: Comparisons with other mammals in relation to diet. Journal of Morphology, Wiley, 1980, 166, pp.337-386. ffhal-00561758
  3. Kay, Richard. (1975). The Functional Adaptations of Primate Molar Teeth. American Journal of Physical Anthropology. 43. 195 – 215. 10.1002/ajpa.1330430207.
  4. Koebnick, C., Strassner, C., Hoffmann, I., & Leitzmann, C. (1999). Consequences of a Long-Term Raw Food Diet on Body Weight and Menstruation: Results of a Questionnaire Survey. Annals of Nutrition and Metabolism, 43(2), 69–79. https://doi.org/10.1159/000012770
  5. Wrangham, R. W. (2010). Catching fire: how cooking made us human. London: Profile Books, Cop.
  6. Roebroeks, W., & Villa, P. (2011). On the earliest evidence for habitual use of fire in Europe. Proceedings of the National Academy of Sciences, 108(13), 5209–5214. https://doi.org/10.1073/pnas.1018116108
  7. Herries, A. I. R., Martin, J. M., Leece, A. B., Adams, J. W., Boschian, G., Joannes-Boyau, R., Edwards, T. R., Mallett, T., Massey, J., Murszewski, A., Neubauer, S., Pickering, R., Strait, D. S., Armstrong, B. J., Baker, S., Caruana, M. V., Denham, T., Hellstrom, J., Moggi-Cecchi, J., … Menter, C. (2020). Contemporaneity of Australopithecus, Paranthropus, and early Homo erectus in South Africa. Science, 368(6486), eaaw7293. https://doi.org/10.1126/science.aaw7293

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