Cooking
Cooking of food occurs only among humans (with the exception of some captive apes that assist humans in cooking). The invention of cooking allowed humans to extract more nutrients from various foods, by making the foods more digestible, and by destruction of toxins, and other anti-nutrients including protease inhibitors and lectins or infectious agents. This provided a massive widening of the dietary niche, with access to many novel foods. The invention of cooking may have also allowed humans to increase hunting activities and evolve larger brains by increasing the quality of their diets.
Cooking refers to applying heat in the preparation of food. It is sometimes used to describe fermentation also. It is known only among humans, except for captive apes that have learned to eat cooked food and to cook it with the assistance of humans. Cooked food is more digestible than raw food, meaning that a higher proportion of nutrients are digested in the small intestine. The costs of digestion are also lower for cooked food than raw food.5 The two effects cause cooked food to yield consistently greater net energy than raw food, both in humans and other animals. No formula is available for estimating the percentage increase in energy gain obtained by cooking food, but it may be up to 50% or more for foods containing complex carbohydrates such as starch.10 In addition to providing extra energy, cooking tends to remove or reduce toxins (from plants or pathogens), anti-nutrients (such as tannins) and pathogens (such as bacteria). By making potential food items more rewarding and safer, cooking substantially broadens the dietary food niche, which means that hominids who learned to cook would have been able to extend the range of habitats that they could live in. It also reduces the time spent chewing by several hours per day.7 The freeing of time would have enabled individuals to spend more time in preferred activities such as hunting. Cooked food has been argued to be a physiological necessity for releasing energy constraints on the evolution of large brain size.9,6
All animals tested to date are similar to humans in preferring their food to be cooked, including the great apes and domesticated species (dogs, cats, rats, mice).11 The preference for cooked foods even in species encountering it for the first time is explained by cooked food giving easily perceived signals of high digestibility, such as reduced starchiness and toughness, and increased glucose and aminoacids. Experiments with chimpanzees show that they possess several of the cognitive abilities needed for cooking, including understanding the transformation of raw food into cooked food and being willing to postpone eating raw food in order to get the benefit of cooking. This suggests that once hominids had achieved control of fire, cooking would have followed swiftly.6
Consumption of most food in a cooked state (whether hot or cold) is a cross-cultural universal across human populations. Among hunter-gatherers foods eaten raw tend to be snacks consumed during foraging expeditions. Most foods eaten in camp are cooked, the main exception being collected fruits. Domestic cooking tends to be done by mothers in all societies, whereas fathers cook mostly on public occasions. Cooking is thus less universal than the eating of cooked food.9
Thanks to having a relatively small mouth, teeth, stomach and colon, humans are biologically obliged to eat foods of high caloric density and digestibility. No raw wild diets are known that satisfy these needs longterm. In theory a sufficient amount of raw, fat-rich animal matter could do so (such as marrow and brains), but in practice only cooked food is known to provide an adequate diet. Even under energetically easy conditions of urban life, women eating raw diets, using high-energy domesticated plants and animals and electric blenders, lose so much energy that at least half do not ovulate.
When hominids first started consuming cooked food they would have immediately obtained more energy than before. Increased energy would have been selectively advantageous in shortening the inter-birth interval, increasing growth rate, and strengthening the immune system. Populations that cooked would therefore have higher growth rates than others. After cooked food had become predictably available, selection in favour of energy maximization would have led to selection for reduced digestive anatomy.
almost certainly other species (including Neandertals) throughout much or all of the Pleistocene. The predictability of highly digestible energy in cooked food has been argued to help promote key features of human life-history (long lives, fast reproduction), anatomy (small gut), behaviour (much non-foraging time) and cognition (large brain, high patience).3
No other living species has been observed cooking in the wild.
References
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Cooked starchy food in hearths ca. 120 kya and 65 kya (MIS 5e and MIS 4) from Klasies River Cave, South Africa, , Journal of Human Evolution, 2019/06/01/, Volume 131, p.210 - 227, (2019)
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Hominin fire use in the Okote member at Koobi Fora, Kenya: New evidence for the old debate., , J Hum Evol, 2019 08, Volume 133, p.214-229, (2019)
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Control of Fire in the Paleolithic: Evaluating the Cooking Hypothesis, , Current Anthropology, 2017/08/01, Volume 58, Issue S16, p.S303 - S313, (2017)
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Cognitive capacities for cooking in chimpanzees., , Proc Biol Sci, 2015 Jun 22, Volume 282, Issue 1809, p.20150229, (2015)
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Energetic Consequences of Thermal and Non-Thermal Food Processing, , Cambridge, Massachusetts, (2012)
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Metabolic constraint imposes tradeoff between body size and number of brain neurons in human evolution, , Proceedings of the National Academy of Sciences, 2012/11/06, Volume 109, Issue 45, p.18571, (2012)
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Phylogenetic rate shifts in feeding time during the evolution of Homo., , Proc Natl Acad Sci U S A, 2011 Aug 30, Volume 108, Issue 35, p.14555-9, (2011)
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Human adaptation to the control of fire, , Evolutionary Anthropology, 10/2010, Volume 19, p.187-199, (2010)
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Catching Fire: How Cooking Made Us Human, , New York, p.309, (2009)
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The energetic significance of cooking., , J Hum Evol, 2009 Oct, Volume 57, Issue 4, p.379-91, (2009)
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Great apes prefer cooked food, , Journal of Human Evolution, 08/2008, Volume 55, Issue 2, p.340-348, (2008)
