To prove that cooking actually does save energy, Wrangham partnered with Stephen Secor, a University of Alabama biologist who studies the evolutionary design of the digestive system. They found that the python—an animal model with easily studied gut responses—expends less effort breaking down cooked food than raw. Heat alters the physical structure of proteins and starches, thereby making enzymatic breakdown easier.
Wrangham’s theory would fit together nicely if not for that pesky problem of controlled fire. Wrangham points to some data of early fires that may indicate that H. erectus did indeed tame fire. At Koobi Fora in Kenya, anthropologist Ralph Rowlett of the University of Missouri–Columbia has found evidence of scorched earth from 1.6 million years ago that contains a mixture of burned wood types, indicating purposely made fire and no signs of roots having burned underground (a tree struck by lightning would show only one wood type and burned roots). The discoveries are consistent with human-controlled fire. Rowlett plans next to study the starch granules found in the area to see if food could have been cooked there.
Still, most researchers state that unless evidence of controlled fire can be regularly confirmed at most H. erectus sites, they will remain skeptical of Wrangham’s theory. Moreover, other food-based theories can explain the body and brain expansion without flames. One is the expensive tissue hypothesis, proposed in 1995 by Leslie C. Aiello, professor emeritus of biological anthropology at University College London, and physiologist Peter Wheeler of Liverpool John Moores University in England. The main idea of the hypothesis—that smaller guts correlate with bigger brains in primates—fits with Wrangham’s theory, but Aiello and Wheeler think that energy-dense animal-derived foods, such as soft bone marrow and brain matter, were the reason humans developed these characteristics, not cooking.
Lacking the proof for widespread fire use by H. erectus, Wrangham hopes that DNA data may one day help his cause. “It would be very interesting to compare the human and Homo erectus genetics data to see when certain characteristics arose, such as, When did humans evolve improved defenses against Maillard reaction products?” he says, referring to the chemical products of cooking certain foods that can lead to carcinogens.
Even without such evidence yet, some think Wrangham’s theory is just the thing to shake up the field of human evolution.
“It doesn’t matter who develops these ideas,” says Aiello, who is also president of the Wenner-Gren Foundation, which supports anthropological research. “You have to listen to what Richard is saying because he has some very interesting, original data. Sometimes the most creative ideas come from unexpected places.” She points to Goodall, who surprised the world by proving that humans were not the only toolmakers. “It’s one of the best illustrations I know of the value of primate research informing our knowledge of human evolution and adaptation,” Aiello says.
If Wrangham’s strange ideas turn out to be true, we can thank an early hominid Emeril Lagasse who picked a charred tuber out of a campfire and swallowed it. Without that person, we might never have been able to examine our origins—or enjoy a good grilled steak—in the first place.
This article was originally published with the title Cooking Up Bigger Brains.
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Add CommentBesides the possibility that our ancestors didn't have sufficient control of fire, the other major reason that Wrangham's hypothesis may be wrong is that we don't need to assume that our ancestors ate the same thing as modern day chimpanzees.
Reply | Report Abuse | Link to thisIndeed, it is quite likely that they did not. The food that can give us all the protein and nutrition that is needed for big brains is fish and shell fish. It is quite likely that our ancestors evolved on beaches along lakes and streams (the locations of many of the fossilized remains in Africa today). This is consistent with the Amphibious-generalist hypothesis of human evolution put forward by Andrew Lewis .
http://www.geocities.com/Athens/Acropolis/4314/intromhh.html
All our other aquatic adaptations can also be explained by this theory.
If you visit Africa today you see that only the big animals (and humans) occupy the riparian ecosystems - lions, hippos and crocidiles. All the other animals, including the chimps, don't dare spend much time on the ground along the streams. Yet, these are by far the best ecosystems on the continent - replete with abundant food supplies and water - highly sought after but inaccessible except to the smartest and strongest. This is the key difference between us and chimpanzees - our ancestors took over the beaches sometime in the past and everything we've done since has evolved from this intitial change in habitat.
Colin Buss
I was thinking the same thing about as the above poster about fish. We still eat raw fish today in the form of sushi. Is it really that nutritionally different when it is cooked (fish I mean)? Furthermore, what about nuts? Those are extremely high in protein and fat, and we know our ancestors ate a lot of nuts. Add to that tubers and roots. Doesn't seem cooked food is so mandatory to explain all this required energy and smaller teeth. I always thought cooked food developed as a means to address sanitation more than anything... it was interesting to learn that it is in fact more efficiently digested. PS loved the subtle jab at vegans in there!
Reply | Report Abuse | Link to thisSorry, shouldn't say "sanitation". Anyway, I thought cooked food came about because the heat killed potentially dangerous parasites.
Reply | Report Abuse | Link to thisI think this is a brilliant idea, and it just makes too much sense, possibly because I'm a non-expert who's not bogged down by preconceived notions. Humans cook almost everything, even pet food! Cooked food tastes better - doesn't that at the very least imply an evolved preference?
Reply | Report Abuse | Link to thisRaw fish? Shellfish? Absurd.
For this to be a viable theory, you've got to believe that basically ALL humans ate fish during the ENTIRE million or so years that the bigger brain/smaller gut/weaker teeth evolution thing happened.
That's ridiculous - catching fish efficiently is probably just as complex a process (duh, you need a fishing rod or nets) as controlling fire - and observing fire in action (think forest fires started by lightning) would have been a lot easier and more common than figuring out tools. Remember, this all occurred before even language was invented, or farm animals, or farming, or virtually anything else, by a species only slightly more evolved than today's chimps. Also, keep in mind that no primates use any tool even remotely as complex as a fishing rod or net, or think to catch fish. Does any land creature rely on fish as a major dietary staple?
Or think, if raw fish was so common in our distant past, and indeed fueled our evolution, why is it so rare today (really, of all major cultures, only the Japanese do it)? Why do most people cook fish, if we ALL evolved through eating raw fish?
Lastly, look at the evolutionary angle - if raw fish was so intimately tied to our evolution for even 500,000 years, we would have adapted our bodies and minds more to the ocean. We can't even see underwater! Our hold our breaths for more than a minute of activity! Except for Micheal Phelps, our bodies are obviously designed more for running than swimming. How the can anyone argue that we are adapted to catching and eating raw fish?
I think this is a brilliant idea, and it just makes too much sense, possibly because I'm a non-expert who's not bogged down by preconceived notions. Humans cook almost everything, even pet food! Cooked food tastes better - doesn't that at the very least imply an evolved preference?
Reply | Report Abuse | Link to thisRaw fish? Shellfish? Absurd.
For this to be a viable theory, you've got to believe that basically ALL humans ate fish during the ENTIRE million or so years that the bigger brain/smaller gut/weaker teeth evolution thing happened.
That's ridiculous - catching fish efficiently is probably just as complex a process (duh, you need a fishing rod or nets) as controlling fire - and observing fire in action (think forest fires started by lightning) would have been a lot easier and more common than figuring out tools. Remember, this all occurred before even language was invented, or farm animals, or farming, or virtually anything else, by a species only slightly more evolved than today's chimps. Also, keep in mind that no primates use any tool even remotely as complex as a fishing rod or net, or think to catch fish. Does any land creature rely on fish as a major dietary staple?
Or think, if raw fish was so common in our distant past, and indeed fueled our evolution, why is it so rare today (really, of all major cultures, only the Japanese do it)? Why do most people cook fish, if we ALL evolved through eating raw fish?
Lastly, look at the evolutionary angle - if raw fish was so intimately tied to our evolution for even 500,000 years, we would have adapted our bodies and minds more to the ocean. We can't even see underwater! Our hold our breaths for more than a minute of activity! Except for Micheal Phelps, our bodies are obviously designed more for running than swimming. How the can anyone argue that we are adapted to catching and eating raw fish?
@BKBigFish - Once a small population learns a new way of doing things (eating fish) that confers an evolutionary advantage, then they become the group that is more robust. Therefore, if a group of protohominids had eaten fish, that would theoretically make them stronger and over time they would take the lion's share of resources when in competition with those groups who did not eat fish. So, no, this was not a behavior that spontaneously appeared among disparate proto-human populations, but could have been learned over time after discovery by multiple populations.
Reply | Report Abuse | Link to thisLand animals that eat fish? I can start the list with otters, bears, raccoons...
While eating raw fish is not common in modern cultures, it is by no means rare. In environments where fresh fish is readily available, there are more than a few popular dishes. Ceviche is popular throughout Latin America, poisson cru is well-know in French Polynesia and its sister dish, poke can be found in Hawaii. In fact, when fresh fish was not readily available, there was regular trading of fish between inland and coastal populations in pre-Colombian South America.
One last thing to note is that iodine deficiency is huge problem worldwide for populations that do not have access to seafood. How could we evolve to be reliant on a nutrient that is only available in substantial amounts in sea-derived food products?
Let's start feeding chimpanzees cooked meat and see what happens in a few thousand years.
Reply | Report Abuse | Link to this"Let's start feeding chimpanzees cooked meat and see what happens in a few thousand years."
Reply | Report Abuse | Link to thisI was thinking the same thing.
In many part of the world, people get almost all of there nutritional requirements from eating a mixed diet of nuts, fruits and roots. Nutritional requirement of expanding brain could have been met by our ancestors well through foods available in nature. Probably it was not food but development of tool-making and other cultural changes required for survival of slender bodied ancestor in wild, that kickstarted development of brain.
Reply | Report Abuse | Link to thisI searched this topic because in reading the book "Pottinger's Cats" I'd learned that cats cannot subsist on a diet of which a major component is cooked or pasteurized. The reason that they can't is that they require the enzymes in the raw food (enzymes are denatured at temperatures as low as 118F.) Obviously we can do fairly well on primarily cooked diets, which means that our pancreas has evolved so that it can generate enough digestive enzymes to require few from (raw) food.
Reply | Report Abuse | Link to thisI don't know how long such evolution requires but it does damage the 'raw fish' theory.
Another evolution is the presence of sugar & other simple carbohydrate digesting enzymes in our saliva, which wouldn't evolve on a diet primarily consisting of raw fish. Such amylase enzymes are also injected further downstream in our digestive tract. To me this says that sugars & starches have been a major component of our diets for a very long time, perhaps the dominant component.
It would be interesting to know if we share this type of saliva with our primate kin - if we do that suggests it comes from a common ancestor, i.e. a very, very long time ago. More than a couple of million years back. That would push the raw fish idea out of contention.
Don't read into what I've said as anti-raw food. At present we've gone too far in killing enzymes. While enzymes in foods are great for us, they are the enemy of the food processing industry - they make things spoil. And our great fear of microbes in our food also fuels the killing because enzymes are in the line of fire. Heck, they are pasteurizing or irradiating everything that isn't pre-cooked. Our pancreas, as marvelous as it is, needs some help from our foods - virtually every known disease involves a lack of an enzyme or enzyme co-factor (vitamins are co-factors). So don't throw sticks at the vegans or vegetarians because they typically worry about keeping some food enzymes intact, while most of us give them zero thought.
For you cat lovers, feeding your housebound cat cooked food won't kill it - the problems typically show up in the offspring, worse in the second generation but not a problem in third generation because, as Pottenger found, there won't be a third generation.