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Most large animals have to chew food extensively and form it into a mushy ball that’s easy to swallow. Cooking makes a huge difference—it softens the food and dramatically reduces eating time. Researchers calculated that if we lived like our non-cooking primate cousins, we’d spend about 48 percent of the day eating. But modern humans spend only about 5 percent of the day chowing down. So when our ancestors invented cooking, it gave them a major survival advantage.
So how long have ago did our forebears start barbecuing?
The softer food available via cooking allowed for the evolution of smaller molars and a smaller jaw. Researchers therefore compared the molars and body sizes of extinct hominids with modern humans and other primates. Turns out that Homo erectus and Neanderthals had, and modern humans have, molars that are smaller than would be predicted by looking at general primate evolution. The finding is in the Proceedings of the National Academy of Sciences. [Chris Organ et al, Phylogenetic rate shifts in feeding time during the evolution of Homo]
Based on the appearance of the smaller eating apparatus, the researchers infer that humanity discovered the benefits of cooking about 1.9 million years ago. And we’ve been enjoying the convenience, speed and taste benefits ever since.
—Cynthia Graber
[The above text is a transcript of this podcast.]
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19 Comments
Add CommentI have a brother in law who is morbidly obese. He probably spends 48 percent of the day eating. He certainly has no survival advantage, but maybe we should start a long term study of his children, and chart for jaw and molar dimensions. (Sorry, I have the late summer sillies).
Reply | Report Abuse | Link to thisCorrection: human molars and jaws 'responded to' the invention of cooking by getting smaller... it's really important to use clear language & throw away this "genes want to be selfish" sort of false poetry which assumes everyone is on board with the truth in question.
Reply | Report Abuse | Link to thisA clue to the early evolution of cooking which seems to have been overlooked is the tolerance of the human mouth to high temperatures. We drink hot liquids such as tea, coffee or soup at temperatures which would be scalding or at least very uncomfortable on the skin. This seems to indicate that our ancestors with mouths more capable of eating food hot off the fire survived better. Studying gene variants that let us eat these hot foods, could give a molecular-clock check on the dates for early cuisine!
Reply | Report Abuse | Link to thisThere was no disadvantage to having unusually small molars and jaws when food started to be cooked regularly. This aberration would not have been selected out of our ancestral gene pool. It requires that large molars and jaws would have been a disadvantage somehow however for them to have essentially disappeared. The article here doesn't explain that but it must be part of the hypothesis somewhere.
Reply | Report Abuse | Link to thisThis is Scientific American. Religious American is another site somewhere. "Evolution" is the right word.
Reply | Report Abuse | Link to thisYour comment is perceptive.
Reply | Report Abuse | Link to thisThere are two factors at play here. Factor #1 is that before cooking, larger jaws and molars were required to digest enough food to sustain the body.
Factor #2, which was omitted, is that larger jaws and molars require more food to grow and maintain than smaller jaws and molars.
Before cooking was invented, these two factors balanced each other out. Factor #1 favored larger jaws and molars, Factor #2 favored smaller jaws and molars.
After cooking was invented, these two factors no longer balanced each other out. Factor #1 went away, but Factor #2 favored smaller jaws and molars. So individuals with mutations that created smaller jaws and molars could out-compete individuals without this mutation.
So the average jaw and molar sizes decrease to the point that if the jaw and molar sizes grew any smaller, not enough food could be digested to sustain the body.
A classic example of this situation are fish that live in caves without light. Eyes give no advantage, but having them requires more food to grow and maintain, so individuals with mutations that shrink or eliminate the eyes out-compete individuals with eyes. Lo and behold, fish that live in caves with no light tend to have no eyes.
*[Citation to come.]*. WHEN?
Reply | Report Abuse | Link to thisThe link is here:
http://www.pnas.org/content/early/2011/08/17/1107806108.abstract?sid=3cb579e4-4464-4438-8271-1f1ab75971c3
I believe that Toby's point is that genes did not change because cooking was invented, but that large jaws and molars lost their adaptive advantage when less chewing was required. Natural selection is a more likely explanation than mutation.
Reply | Report Abuse | Link to thisPerhaps humans developed smaller molars and jaws about 2 million years ago, but what evidence established that it was the change to cooking that produced that effect?
Reply | Report Abuse | Link to thisWhen did humans begin eating meat? Perhaps the change in molars was produced not by cooking but by eating softer, more easily digestible food!
As I understand, differences in molars, jaws and jaw muscles vary among all primates depending on their food sources - no other primate cooks!
The authors of the research stated this in the abstract:
Reply | Report Abuse | Link to this*Unique among animals, humans eat a diet rich in cooked and nonthermally processed food. The ancestors of modern humans who invented food processing (including cooking) gained critical advantages in survival and fitness through increased caloric intake.*
Therefore, the scientists are not saying uniquely about cooked foods!
The podcast is wrong in asserting that the research is only related to foods that are cooked (Which signifies: * To prepare (food) for eating by applying heat*).
The research report's abstract states in its opening:
Reply | Report Abuse | Link to this"Unique among animals, humans eat a diet rich in cooked and nonthermally processed food. The ancestors of modern humans who invented food processing (including cooking) gained critical advantages in survival and fitness through increased caloric intake."
As I suggested previously, the researchers do not establish that any "increased caloric intake" is the product of "food processing" and not the result of switching to more nutritional, more easily digested meat.
The abstract continues:
"However, the time and manner in which food processing became biologically significant are uncertain. Here, we assess the inferred evolutionary consequences of food processing in the human lineage..."
Again, it seems that the researchers only presume that changes in molars and jaws were the product of "food processing" rather than food selection.
To the critics, this is not a new hypothesis. It's new information being added to an existing one. The idea of tissue trade offs is not new or particularly ground breaking. It's worth noting that we have a ridiculously small gut to go with our ridiculously large brain for a primate our size. It's also worth noting that other primates, many of whom will eat meat opportunistically (and some even actively hunt it) still have to chew a comparitively long time. Cooking is the single most likely suspect in the selective landscape to allow us to trade one enormously expensive glob of tissue for another one (IE gut for brain). Having a reduction in jaw and tooth size to go with it is simply highly suggestive that this trade off did indeed have something to do with how food was processed. This idea is discussed at length in the book "Catching Fire" by Richard Wrangham and in it he suggests that meat eating may have been our first big boost, but that cooking probably provided the additional impetus to finish the job. Raw unprocessed meat isn't as easy to chew or digest as you might think and there is a substantial boost in absorbable calories from processes like cooking. Raw meat is, nutritionally speaking, a comparably rich source of calories and nutrients and based on the evidence to date less labor intensive than chewing fibrous plant material, but it still doesn't hold a candle to cooked food.
Reply | Report Abuse | Link to thisPeople have a lot of mistaken ideas about the food landscape that would have been available to our ancestors. Modern crops were selectively bred for thousands of years to make the plants we regularly eat. Most bear little resemblance to their wild ancestors. The wild varieties of many edible fruits and vegetables aren't particularly sweet, succulent or easy to eat. Most "Raw" meats that humans consume today have gone through some degree of alternative processes to cooking. Tenderizing, marinating, mixing them with substances that denature the protiens chemically etc. To say nothing of mechanical processing. Most domestic animals we eat have also been bred to make their meat easier to eat (more fat content etc.) For example horse which is actually eaten in many places but not specifically bred for meat production isn't a particularly good source of tender meat. Under 20% of a horse is easily eaten by humans (BLECH!). My main point here is if you are going to denounce the idea based on a blog at least read the rest of the evidence.
JT, it's a blog. If you want more info it's out there to be had. As I said in my earlier post this is an addition to existing converging lines of evidence. There is quite a large body of work on calorie availability between unprocessed and processed foods. While cooking destroys some calories through combustion it makes far more of the surviving material available to our digestive tracts. Raw meat, while much easier to deal with, than raw veggies still isn't comparable to cooked food. Evidence of meat eating in hominids goes back quite a long way and it probably did contribute to some of the gut reduction and brain expansion in our ancestors, but further expansion occured and cooking would certainly fit the bill for re-enforcing selective pressure in that direction.
Reply | Report Abuse | Link to thisAlthough if you need additional evidence you could take a look at any raw foodies you have in your area. They will eat meat, but won't eat anything cooked. They are quite commonly malnourished. The book I mentioned goes into a lot more detail about the existing evidence. The author does do a bit of speculating, but he's quite clear on when he's doing it. Several of my anthropologist friends seem to like the book, if not Mr. Wrangham himself (one of them described him as insufferable).
The cooking hypothesis was first proposed by Richard Wrangham: "The cooking hypothesis, the discovering of the control of fire and the cooking of food, 1,9 million years ago, could explain how and why humans have evolved the way they did". I wonder why he is not mentioned in the podcast. I am also wondering why, when mentioning cooking 1,9 million years ago, barbecuing meat comes in mind with most people. Barbecuing is only one of several cooking technics and often not the most healthiest one. Cooking a combination of foodstuffs, like root, shellfish, fish or a reptile wrapped up in clay, cooked in the embers of a dying fire is far more healthier than roasting a chunk of meat in a hot smoking fire (the relationship between cooking certain foodstufs and the grow and the restructuring of the hominid brain, 1,9 mill. yrs ago, is worth studying). It shouldn't be overlooked that by discovering cooking, hominids made themselves open to the dangers of cooking food wrongfully. When cooked too long or cooked with too much water (hole in the ground filled with water, heated stones and food), essential vitamines can be lost (I suspect that the first generations of cooking hominids were not as healthy as their rawfood ancestors). Good cooking is a complex activity that implies a lot of things. A basic technological level and know-how, specialized tools or tools already in use that has been given an other function, etc., but more important a new look is needed, at the landscape and the plants and the animals that are part of it. Cooking has to be learnt thoroughly and by this learning the relationship between things can be perceived. This learning has to be given to next generations, starting up culture or a whole new kind of culture (if females were central in this cooking culture, this opens new vista's in the importance of the female factor in the evolution of humans). The discovery of cooking was a monumental event in the history of mankind - and of the world. Not because it brought all kind of new foodstuffs or led to physiological adaptions; far more important is the mental/spiritual transformation it brought, a new perception of the world and hominid's place and meaning it it. When studying the idea that cooking started 1,9 million years ago, this should really not be overlooked. Doing research on this subject, I think, in the H. ergaster who cooked the first warm meal at East Africa's Lake Turkana we can recognize ourselves.
Reply | Report Abuse | Link to thisI am interested in your comment, your idea seems so novel
Reply | Report Abuse | Link to thisVery interesting idea about the tolerance of human mouths to high temperatures. Interestingly, it's not just human mouths, though - having had a job as dishwasher, the palms of my hands are capable of tolerating scalding water. Not the rest of my skin, though, so it's something that has to be built up. It might have been that somewhere along the line, we picked up a genetic advantage of being able to acquire an ability to tolerate high heat: those of us who were able to scoot really close to the fire survived.
Reply | Report Abuse | Link to thisThe cooking hypothesis was first proposed by Richard Wrangham. I wonder why he is not mentioned. I am also wondering why, when mentioning cooking as a 1,9 old discovery, most people think of barbecuing. Barbecuing is only one of several cooking technics and often not the most healthiest one. Cooking a combination of foodstuffs, like root, shellfish, fish or reptile, wrapped up in clay, cooked in the embers of a dying fire is far more healthier than roasting a chunk of meat in hot smoking flames. It shouldn't be overlooked that by discovering cooking, hominids made themselves susceptible to the risks of cooking food in the wrong way. For instance, when food is cooked too long or with too much water essential vitamines can be lost (I suspect that the first generations of cooking hominids were not as healthy as their rawfood ancestors). Good cooking is a complex activity that implies a world of things. A basic technological level and know-how, specialized tools or tools that have been given an other function, cooperation, etc., more important a new look at the landscape and the organisms that are part of it is needed. Cooking has to be learnt and to be learnt thoroughly and in the proces of learning, the intricate relationship between the cooker and the natural world can be perceived. What has been learned, has to be given to next generations, starting up a new kind of culture (if females were central in this cooking culture, this opens new vista's relating the importance of the female factor in human evolution). The discovery of cooking was a monumental event in the history of mankind - and of the world. Not because it led to physiological adaptions in hominid's anatomy; far more important is the mental/spiritual transformation it brought, a new perception of the world and hominid's place in it.
Reply | Report Abuse | Link to thisThanks all for the information overload, but I am unapologetically not a student of anthropology.
Reply | Report Abuse | Link to thisBased on this SA article and the PNAS article abstract:
Organ et al, (2011), "Phylogenetic rate shifts in feeding time during the evolution of Homo",
http://www.pnas.org/content/early/2011/08/17/1107806108.abstract?sid=3cb579e4-4464-4438-8271-1f1ab75971c3
- these researchers seemed to presume that the identified changes in human molars and jaws and chewing was only due to processing/cooking food.
Again, the PNAS abstract states:
"Unique among animals, humans eat a diet rich in cooked and nonthermally processed food. The ancestors of modern humans who invented food processing (including cooking) gained critical advantages in survival and fitness through increased caloric intake."
Essentially unique among primates, humans consume a large amount of meat. My point is that the change to eating meat could also have reduced Homo erectus' requirements for heavy duty chewing capabilities. As a result, I suggest that it cannot be definitively determined from fossil evidence of human jaws and teeth when cooking and food processing began.
Beyond that, I recognize that raw meat is not very easy to chew, but then lions would have a difficult time chewing nuts and roots. By the way, lions don't spend a lot of time eating, either...
my mother's cooking certainly tasted as if it were 2 million years old.
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