What Makes Us Human? Cooking, Study Says


Did you eat a hot meal today? It’s a smart thing to do, as our ancestors learned.

According to a new study, a surge in human brain size tehat occurred roughly 1.8 million years ago can be directly linked to the innovation of cooking.

Homo erectus, considered the first modern human species, learned to cook and doubled its brain size over the course of 600,000 years. Similar size primates—gorillas, chimpanzees, and other great apes, all of which subsisted on a diet of raw foods—did not.

“Much more than harnessing fire, what truly allowed us to become human was using fire for cooking,” said study co-author Suzana Herculano-Houzel, a neuroscientist at the Institute of Biomedical Sciences at the Federal University of Rio de Janeiro in Brazil.

A Diet Unfit for King Kong

Herculano-Houzel and colleague Karina Fonseca-Azevedo measured the body and brain masses of primates and compared them with their caloric intake and hours spent eating. Unsurprisingly, the results showed a direct correlation between calories and body mass. In other words, the bigger you are, the more you have to eat.

Written By: Nicholas Mott
continue to source article at news.nationalgeographic.com


  1. This is interesting.  If cooking our food had the effect of making digestion easier and allowed encephalization, then perhaps other cultural practices we take for granted are part of a “runaway” process that encouraged further brain growth.  For instance, our bipedalism led to freeing the hands, which led to handling branches, which led to handling fire, which both led to new hunting tactics, which led to the cooking of meat, which led to cooking in general, which (as per the article) allowed brains to grow with more nutrients, giving evolution a new scope for further adaptations to be implemented in the brain, and thereby leading to the brain expanding as a side effect, all over evolutionary time.

    However, I’m not going for the hypothesis that “cooking is the key to our success”. Judging from what’s here, it is a catalyst. Just because it allowed the brain to expand, doesn’t mean it explains why the brain should expand. For that, independent evolutionary pressures are needed. For instance, our omnivory, our social tactics and folk biology, our ability to steal some adaptations from other animals, and our exploratory impulses and tendencies to spread further afield if possible.

  2. The notion that eating cooked food saves energy in digestion is unconvincing. I almost say “ridiculous”.  How can this save energy? Hundreds millions of years of evolution improved the enzymes to digest molecules in their natural structure. Cooking (high temperature) changes the structure, at least in proteins, known as denature.  Do you think that enzymes love strange substrates better than familiar ones? OK, cooked food is easy to chew and may save energy in chewing. How much energy is needed to gather wood, make fire, and cook? How much time is needed to do these? I did search the literature for review articles in this subject. There is no solid evidence supporting this saving energy notion.

  3. I think they’re claiming that experiments show that digestion is more efficient and complete when food is cooked, especially meat. Much of the food we eat from the supermarket is already cooked during manufacturing, like bread & breakfast cereals. We just basically reheat or complete the cooking process at home.

    There’s other aspects to the use of fire for cooking beyond making things easier for digestion enzymes.
    1.Food toxicity – expands the range of kinds and quality of food that can be safely consumed.
    2.Improves the taste – glycation of proteins adds more complex flavours.
    3.Hot food can be more enjoyable. He who chops wood for fire gets warm twice, and 3x if eating hot food.
    4.Preparing fires and shared eating are the focus for social gatherings.
    5.Smell of smoke can trigger bushfire instincts in large cats – deterring some potential predators from lurking around camps.
    6.Fat harvesting – coagulated saturated animal fat can be dripped off large carcasses. The product is stable, solid after cooling, light, high energy content, easily transportable, has a very wide range of technological applications, and can be safely stored for a very long time to support long distance travel, starvation insurance, and commodity trading. This technology makes it worthwhile for humans to kill far more prey than would meet immediate needs, and therefore provides an economic incentive to exterminate entire species of large herbivores. Which seems to correlate with ecological history.

    On the appropriate diet for humans in the age of modern agricultural technology and fast foods there is some light on the horizon:



  4. Even apes, when offered a choice between raw foods and spaghetti/meatballs, 
    took the meatballs every time

    Interesting, but not surprising, considering our kinship. Did they try the cooked noodles?

    I personally prefer Scarlatti and meatballs 😉

  5. Wouldn’t this article be related to the other ones here about jaw size/brain size? Cooked food is usually easier to chew. Less need to chew through hide and other tough foods would allow jaw strength and size to decrease allowing our brains to expand. ??

  6. Even in the third world in modern times, you’d be surprised at how difficult it is to keep any extra body fat at all.  My home base these days is the US where it seems impossible to lose weight at all (sedentary couch potatoes and delicious junk food on every corner) but when I spend weeks in Europe I lose 2 to 3 pounds per week with no effort.  We walk much more every day there and buy food and cook food differently than we do in the States. 

     But it’s the next transition that is the most telling.  If we spend a few weeks in North Africa I can count on dropping at least 5 pounds per week without trying.  This is cooking for large extended families.  A few adults will walk to the local market, carry the fruit, veg, semolina, cooking oil, and a small amount of meat if there is something affordable, back to the home.  Everything is cooked absolutely from scratch, three meals a day for extended families of 10 to 20 people.  They no sooner finish one meal from buying it to cooking and serving to cleaning up then it’s time to start the next one.  This goes on from sunup to sundown. There is never enough food served for everyone to eat their fill. Dairy products are rare.  Everyone eats a little something, but with all the hard physical work and this “no frills” diet, it’s easy to see that it’s not easy to keep weight on.

    Then there’s the cleaning.  Extended families create days of never ending work.  There are always plenty of children of all ages and an elderly generation that needs help and extra care.  Clothing must be washed by hand.  For this many people it’s an all day task to wash a days laundry and most people wear their clothes for a few days running before they add them to the wash pile. It’s not unusual for people to walk for several miles every day.  Kids walk for miles to get to their schools and markets could be a mile away.  Cars are a luxury in the third world.  You get the picture. 

    On my first extended stay in North Africa, within 3 months I was down to a very thin state.  Then I got pregnant.  I had a bad case of “morning sickness” that caused me to lose even more weight, just at a time when I should have increased my calorie intake.  Three more months of losing weight put me in a state of dangerous weakness.  I was emaciated. I couldn’t walk without blacking out and didn’t care to even try. I thought I would die in that place and my baby with me.

    gangan, Try not to underestimate the critical importance of a few extra calories to an underweight human body.  I know this is a long dragged out anecdotal story with no data to address the doubts that you expressed above, but what I know about life in a harsh, unrelenting environment is that every calorie counts. I have no doubt that the difference between cooked food and raw food is the difference between life and death.  It’s easy to die in the third world.  When someone is underweight already, a serious illness and/or a pregnancy can mean you’re a dead duck.  No wonder our female reproductive system shuts down at some point of dangerous weight loss. I wish mine had shut down sooner than it did.  That pregnancy almost starved me to death.

  7. The causality could be completely reversed. Suppose sexual selection for big brains is the reason for brain growth. But this is expensive and therefore brain size stays at the same level. But now some hominids learn to cook their meal which provides extra calories. Then sexual selection for big brains can continue. So it’s not the cooking itself that drives brain growth it just provides the right boundary conditions. Seems more logical to me.

  8.  Laurie,  First, that is not my point. Second, I won’t argue that cooked food is now essential for us to survive, because after eating cooked food for hundreds thousands of years, we are at the point that we cannot go back to eat raw meat as we do not have the strong jaws, teeth, and muscles. Cooking has undoubtedly shaped us. The question is how.  Saving energy for digestion?

  9. Have you read the book Catching Fire How Cooking Made Us Human by Richard Wrangham?  Or anything else by him?

  10. I have not read his book, but his review articles on this subject. In one of his 2009 articles, he used very cautious language to suggest that cooking saves energy in digestion. By the way, based on my literature search, he does not seem to have done much research on this matter, but somehow, has written more reviews than original papers. Anyway, I usually do not use books as sources of scientific truths.

  11. If you are looking for an explanation on the molecular level I’ll bow out and hopefully someone with that knowledge will jump in.  My interest in this subject is much more Anthropological, as you can easily see from my previous comment.  I’m also interested in the A&Physiology of human evolution.  It’s the big picture that captures my interest although you are within your rights to demand evidence on a molecular level or whatever level you care to examine.  If Wrangham was cautious about making that statement in a 2009 paper, he sure is saying it bluntly in his book which was also published in 2009. I can hardly blame anyone for being cautious but that’s not my impression of him in this book.  Granted I have no problem with his line of thinking so I’m not exactly bruising for a fight.  Later in the book he makes some claims about pair bonding in relation to cooking that pissed me off severely, but that’s a subject for another day.

    I still recommend the book to you in any case.  I’m just leafing back through it now and there may be enough data there to interest you, especially chapter three, The Energy Theory of Cooking.

  12. I’m no expert in molecular biology but I know the whole area is incredibly complex. Though it seems reasonably plausible that a little less energy would be required to digest cooked protein. Someone may need to correct me.

    Probably there’s not much of an energy saving by cooking food in normal circumstances, but potentially there’s a significant energy saving in emergencies – which is where selection pressure is most acute. Evolution is likely to have given us various traits that are only occasionally relevant in unusual circumstances.

    Proteins are very long and complex structures. Large amounts of protein are consumed when people eat muscle tissue. This protein can be a significant energy source, as well as providing nutrient components to assemble new structural and functional proteins within our own cells. Protein energy would have been extremely valuable for our hunter gatherer ancestors in the late winter when most prey species are very lean and no longer carried much accumulated fat from the previous summer grazing. Fat is always the preferred energy food, as indicated by the tastiness of a steak depending very much on the amount of fat that is interspersed with the muscle fibres. But our bodies have evolved to eat what’s seasonally available. 

    (One of the reasons that the likes of the Eskimos were not so much marginalised and driven out of the best lands, as I was taught at school, is that the winter hunting in the arctic area can actually be much better than in more temperate locations owing to seals having significant amounts of blubber for insulation.)

    Heating at cooking temperatures violently jiggles fragile protein structures out of shape and it wouldn’t take much of this kind of heat stress to break them up into shorter chunks. Long strings of protein are relatively massive molecules so it makes sense that cooking would partially unravel them and shorten them, at least on average. (Cooking is basically whacking them with high velocity water molecules.) These protein nutrients can only be used to assemble new proteins once they are fully dismantled into their sub-units. A large proportion of protein ingested is converted to glucose and most of that is then converted to fat, so eating protein is mostly no different to eating carbohydrate.

    You can injure yourself from chronically eating too much protein in exactly the same way as for eating too much carbohydrate. This occurs when there is an excess of glucose in the blood for prolonged periods. (Like several decades.) Long protein molecules already produced by our cells are susceptible to additional cross-linking via glucose, similar to sulphur cross-linking between rubber molecules during vulcanisation. Some of the affected proteins will no longer perform as specified. Typically causing things like arterial linings to become less flexible and prone to tearing, and lenses in eyes to no longer relax or bulge correctly. Some functional proteins can also be altered by glucose cross-linking so that they can’t be easily broken down during normal cellular maintenance. They end up accumulating into a cloggy mess that interferes with cellular processes and resist the normal enzymes that break them down for recycling. Pretty much anything can happen when enough such spanners are thrown into the works.

    There is some quick energy to be obtained from eating protein, assuming the body can use it immediately instead of converting it to fat. Fat is where it mostly ends up for long term energy storage and as a means of getting the glucose out of circulation to protect the integrity of functional and structural proteins in the body. The more that very large protein molecules are pre-processed via heating to partially dismantle their structure then the less energy would be required to obtain the same result during digestion.
    A common error when considering energy from food is that glucose is assumed to be the primary energy source for metabolic activity. But the body can’t really store enough glucose to get through the kinds of intensely stressful activities that might have generated significant selection pressure on our ancestors. The alternative of stripping down and digesting our store of structural protein in our bodies can occur, but that’s not exactly a great idea from an evolutionary perspective. There must be a net energy benefit there, despite the lack of cooking, or it wouldn’t occur. This is obviously relevant as an emergency energy source, and as an aid for anorexics to more rapidly disintegrate. And carrying around surplus muscle mass is also not good energy economy for humans. A small amount of stress will stimulate muscles to grow, assuming there’s sufficient protein nutrients available, but a period of lack of stress will also cause those same muscles to rapidly shrink as their protein is consumed either for direct glucose energy or to store as fat, which might be more readily accessed later in some other emergency.

    The main thing is that protein pretty quickly gets converted to fat after it’s been digested. This requires dismantling the proteins right down to relatively small molecules. (Glucose molecules are not very large.) The more that these large proteins can be smashed about and ripped apart by heat stress then the easier this process. Only a tiny bit of the protein eaten normally gets left intact to be employed as nutrients to assemble new proteins.

    It might be more energy efficient, and healthier, for humans to just eat fat, but another of the interesting aspects of cooking is the sex division of labour in humans. One of these sexes tends to perform a disproportionate amount of work in food preparation. So while there may be little direct energy advantage from cooking when accounting for the full economics, including collection of firewood etc, it may make more sense if someone else is providing the bulk of this labour. Selection pressure might tend to eliminate individuals who failed to appreciate this situation.

  13. I think this light and short piece was just meant to be a “food for thought” article and not an end all, be all explanation for what make us human.

  14. Pete H

    Here’s what Wrangham says about sexual division of labor in humans in Catching Fire, Chapter 7, The Married Cook, page 174:

    “The food guarding, provisioning by females, and respect for possession found in animals are associated with males competing over sexual access to females, but only in humans have they led to households.  Something about humans is different from other species.  A woman’s need to have her food supply protected is unique among primates and provides a sensible explanation for the sexual division of labor.

    The proposal that the human household originated in competition over food presents a challenge to conventional thinking because it holds economics as primary and sexual relations as secondary.  Anthropologists often see marriage as an exchange in which women get resources and men get a guarantee of paternity.  In that view, sex is the basis of our mating system; economic considerations are an add-on.  But in support of the primary importance of food in determining mating arrangements, in animal species the mating system is adapted to the feeding system, rather than the other way around.  A female chimpanzee needs the support of all the males in her community to aid her in defending a large feeding territory, so she does not bond with any particular male.  A female gorilla, however, has no need for a defended food territory, so she is free to become a mate for a specific male.  Many such examples suggest that the mating system is constrained by the way species are socially adapted to their food supply.  The feeding system is not adapted to the mating arrangement.  The consequences of a man’s economic dependence takes different forms in different societies, but recall that according to Jane Collier and Michelle Rosaldo, his needing a wife to provide food is universal among hunter-gatherers.  Food, it seems, routinely drives a man’s marriage decision more than the need for a sexual partner.”

    Here is his closing paragraph for the same chapter.  Page 177:

    “The idea that cooking led to our pair-bonds suggests a worldwide irony.  Cooking brought huge nutritional benefits.  But for women, the adoption of cooking has also led to a major increase in their vulnerability to male authority.  Men were the greater beneficiaries.  Cooking freed women’s time and fed their children, but it also trapped women into a newly subservient role enforced by male-dominated culture.  Cooking created and perpetuated a novel system of male cultural superiority.  It is not a pretty picture.”

    Is this the “situation” you were referring to in your last paragraph?

  15. I’ll put that book on my reading list.

    I think that division of labour might be a key driver of intelligence growth in humans. Perhaps not initially, but complex division of labour only becomes possible if most of the mental tools already exist for other purposes: empathy, more complex language, tolerance, and ability to intuit costs and benefits, delayed gratification and planning (time preference). Once the benefits of division of labour kick in then there would be further selection advantages to optimise these traits. The extra energy fuel for large brains being obtainable owing to the enhanced fuel obtaining capability owing to the increased intelligence. Incremental reinforcing steps rather than some kind of technological or mutation breakthrough.

    Cooking would be a crucial element, but not the only factor.

    There would have been an existing physical basis for division of labour owing to the long dependent childhood and lactation, which means females tend to have diminished range owing to the weight handicap of carrying small children. So it makes sense that the males range further when foraging for food. Which leaves the females to gather resources in closer proximity to the home camp. Beyond child-bearing, the division of labour between hunting and gathering seems pretty fundamental in humans, and follows from the child-bearing and having intelligent children to raise.

    The division of labour isn’t purely a division of the product of labour. There’s other opportunity cost aspects, as in the theory of comparative advantage. It also involves time and risk factors. Hunting takes more time, has a much higher risk of failure, and has sporadic rewards. There can be huge payoffs, but mostly nil payoffs. While gathering is much lower risk – more reliable return. Time and energy invested in gathering might be more successful in acquiring food energy. A key aspect of division of labour is increasing specialisation, despite having the capability of engaging in different specialisations or generalising. One option must be committed to for the process to be effective. A small bias in one direction would tip the balance that same way.

    So the economic basis of pair bonding might depend on risk off-setting. The ROI for hunting involves large gains and large risks. Doing so only makes sense if there’s a way of mitigating the risks. Which would be the ongoing complimentary investment in gathering. This role falls to the female owing to their existing constraints on travel. 

    There’s an argument that females as property arises only in connection with monetary systems. A human life being the ultimate commodity traded. (In the book by David Graeber – Debt: The First 5000 Years.) I think that there’s a flaw in Graeber’s argument that money is a form of debt, but this book is still a very good explanation of other aspects of human cooperation and exchange of resources. Division of labour inherently involves trading and exchange, which involves property valuations. And property is valued according the services it provides over its anticipated serviceable lifespan. Human minds are optimised to be very sensitive to detecting cheaters who default on trading obligations. There are difficult mathematical problems that most people struggle with but which suddenly become easy to process when reframed as problems of social cooperation and defection.

    According to Graeber male superiority via patriarchy would naturally arise when money becomes prevalent. Perhaps it is cooking that originally created money.

    I think that monetary commodities may have been around for much longer than is generally appreciated. This might be in the form of rendered fat from animal carcasses. Which depends on cooking in the extraction process. It would makes sense for male hunters to render fat at remote kill sites rather than to transport entire carcasses, and associated protein food over long time and distances back to the home camp. Rendered fat is very portable and durable, and would be an ideal commodity of exchange, and inherently valuable itself. There is a long list of the essential qualities of a money, and fat seems to match this list quite well. Harvesting animal protein for food energy would only be a primary option for hunters during seasons when animal carcasses are relatively lean, so the fat just isn’t available in large quantities.

    It may be that cooking, for rendering fat, is what enabled rapid human expansion out of Africa. But it only makes sense if there are absolutely huge, but rare, gains to be obtained. Which implies storage of food resources acquired from sporadically successful hunts. Which is interesting as there was a previous article here somewhere that indicated that humans don’t appear to have brought fire with them when migrating out of Africa. It was something that was discovered later. This doesn’t make sense to me. The presence of large herds of animals unaccustomed to human predation would have been an essential stepping stone for initial human population expansion.

    If humans could harvest large amounts of animal fat then this would enable their rapid expansion into new territory. Herds of large animals unaccustomed to the need to avoid humans might be relatively easy prey to hunters. It would make sense for these hunters to kill more than they need and exterminate entire herds over subsequent years, and even entire species, in order to extract the fat while discarding most of the otherwise usable carcasses. This relatively durable resource (low rancidity of saturated fat) would temporarily fund travel and exploration, with the situation returning to normal after ecosystems had restabilised following human colonisation.

    There probably isn’t much evidence for this though. Aside from the inevitable species extinctions associated with human encroachment.

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