{"id":3508,"date":"2012-11-09T06:19:12","date_gmt":"2012-11-09T14:19:12","guid":{"rendered":"http:\/\/blogs.nwic.edu\/briansblog\/?p=3508"},"modified":"2012-11-11T11:39:28","modified_gmt":"2012-11-11T19:39:28","slug":"did-cooking-lead-to-bigger-brains","status":"publish","type":"post","link":"https:\/\/blogs.nwic.edu\/briansblog\/2012\/11\/09\/did-cooking-lead-to-bigger-brains\/","title":{"rendered":"Did Cooking Lead to Bigger Brains?"},"content":{"rendered":"

Our brains consume 20% of our body’s energy when resting compared with 9% in other primates. Scientists have suggested that cooking may have helped humans get that extra energy while spending less time foraging<\/a><\/strong>, because cooking effectively predigests food, making it easier for our guts to absorb calories.<\/p>\n

Now, a new study supports this idea, finding that raw food alone wouldn’t have allowed our ancestors’ brains to grow: They would have had to spend more than 9 hours a day eating to get enough energy.<\/p>\n

Join anthropologists Suzana Herculano-Houzel and Richard Wrangham as we answer your questions about how cooked food might relate to bigger brains<\/a>.<\/p>\n

You can submit your questions before the chat starts or at any time during the live Q&A. Find us on Twitter at #ScienceLive<\/strong>. And don’t forget, this and other chats are archived<\/a>.<\/p>\n

Here is the link to the archived chat: <http:\/\/news.sciencemag.org\/sciencenow\/2012\/11\/live-chat-did-cooking-lead-to-b.html<\/a>>.<\/p>\n

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And here is the text from the chat:<\/p>\n

Thursday November 8, 2012<\/div>\n
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Ann Gibbons:<\/div>\n

Welcome everyone to what will be a lively debate, I\u2019m sure. We have two eminent researchers who are particularly interested in how our ancestor got enough energy to expand their minds, so to speak, starting 1.8 million years ago when our direct ancestor Homo erectus began to grow a bigger brain. They come to this question from different perspectives. Suzana Herculano-Houzel is a neuroscientist at the Federal University of Rio de Janeiro, Brazil, where she heads the Laboratory of Comparative Neuroanatomy, and a scholar of the James McDonnell Foundation and of the Brazilian National Research Council (CNPq). In her lab, she has counted the number of neurons in different animals\u2019 brains and calculated how much energy mammals, including apes and humans, need from their diet to fuel those brains. Richard Wrangham is a biological anthropology at Harvard University interested in chimpanzee behavioral ecology and the evolution of violence. He proposed that the invention of cooking was essential to get enougth energy to grow a bigger brain. Let\u2019s debate!<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:02\u00a0Ann Gibbons<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Ann Gibbons:<\/div>\n

1. How does cooking food allow humans to get more energy from it?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:03\u00a0Ann Gibbons<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Richard Wrangham:<\/div>\n

Cooking increases the net energy gained from food from 2 main routes. (1) It increases digestibility (the proportion of food that gets digested and absorbed). For instance cooking is estimated to increase the digestibility of starch in grains by around 30%. It also increases the digestibility of meat, by denaturing the protein. (2) It reduces the physiological costs of digesting our food – because cooking softens food, so it is easier to digest.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:06\u00a0Richard Wrangham<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Diana Gainer Diana Gainer :\u00a0]<\/div>\n

The fossil record suggests an enlargement of the hominin brain pretty early, since Homo erectus brains were considerably larger than those of australopithecines. That means almost 2 million years ago, hominins would have had to be using fire consistently to cook at least some foods. Is there any physical evidence of the use of fire that early?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:06\u00a0Diana Gainer<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

Brain size, judged from cranial capacity, doubled in size over time within the species Homo erectus. That means that initially individuals had a brain that was probably not much larger than that of australopithecines, but over the course of the next million years or so, brain size doubled. This is consistent with evidence of use of fire for cooking around 1 million years ago, and possibly as early as 1.4-1.5 million years ago, around the time when the first Homo erectus were around.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:07\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

About Richard’s answer regarding cooking: I’d like to add that cooking also decreases tremendously the amount of time required to ingest food – meaning to eat, simply. That means that food not only yields more calories per gram, but also more calories per time – which is something that we propose was fundamental for human evolution.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:08\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Chris Chris :\u00a0]<\/div>\n

Dear panelists – do we know whether other animals also have a taste for cooked vs. non-cooked foods?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:09\u00a0Chris<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Richard Wrangham:<\/div>\n

Several animals have been tested in captivity – dogs, apes, rats, mice – and they all prefer cooked food. Nothing much in the wild, except that chimps in Senegal eat Afzelia beans only after they have fallen from the tree and been cooked on the ground by a bush-fire!<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:09\u00a0Richard Wrangham<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Orlandito Cruz Jr. Orlandito Cruz Jr. :\u00a0]<\/div>\n

actually eating raw.foods you get.more<\/a> nutrition out of it than cooked foods. specially when you chew your food thoroughly. if anything its best to egg raw organic fruits and veggies. i dont know where you’re getting info on raw foods not being good enough nutrition when it’s way beyond healthier to eat raw veggies and fruits than cooked ones.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:12\u00a0Orlandito Cruz Jr.<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

Orlandito, “more nutrition out of raw than cooked foods” might be true about not losing vitamins in the boiling water, but that’s not the issue here; rather, the point is that cooking increases the caloric value of foods, by making them easier to chew, more digestible, and hence with higher absorption.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:12\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Lakshmi Krishnamurthy Lakshmi Krishnamurthy :\u00a0]<\/div>\n

Doesnt cooking reduce the nutritional value of food and thus less energy to brain?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:13\u00a0Lakshmi Krishnamurthy<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Richard Wrangham:<\/div>\n

Cooking reduces some vitamins but it always increases energy content. See above, 3.06<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:13\u00a0Richard Wrangham<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Doug Wilder Doug Wilder :\u00a0]<\/div>\n

If an experiment began feeding chimpanzees cooked, high-quality, meals, might we see any significant cognitive development withing a few generations? Or more energy consumption by chimp brains when at rest?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:17\u00a0Doug Wilder<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

Hi Doug, in several animal sanctuaries chimps are already fed cooked, high-quality meals – though they haven’t learned to cook themselves, which would keep them dependent on their humans cooks… it’s definitely an interesting thought experiment, but one that is unlikely to be borne our anytime soon. It would take probably many hundred generations to get an answer. But, in theory, yes: if energy is no longer a constraint, AND having more neurons does give an advantage, then one would expect an increase in brain size and abilities over evolutionary time.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:17\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Dr. Manson Dr. Manson :\u00a0]<\/div>\n

My question to both experts is: What are the main disadvantages of eating raw food in modern times as opposed to eating a balanced diet like it’s normally recommended by nutritionists\/dietitians meant for the general public. I<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:17\u00a0Dr. Manson<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Richard Wrangham:<\/div>\n

Actually raw food diets are highly beneficial to most adults in the west since so many of us are overweight, and raw diets are a great way to lose weight. It would be dangerous for children to rely on a raw diet because of the risk of poor growth to brain and body. For adults there are a few risks that you have to watch out for, such as low bone mass, and low levels of HDL cholesterol (the “good” cholesterol). Other disadvantages include a lot of time spent in food preparation!<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:17\u00a0Richard Wrangham<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Chris Chris :\u00a0]<\/div>\n

What do we know about the “enzymes” that some nutritionists say are released when, say, a vegetable is shredded up (and these enzymes are good for you)? Does cooking affect enzymes, and how?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:21\u00a0Chris<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

Hi Chris, the enzymes present in food are broken down by digestion and turned into amino acids, which are then used by the body in metabolism and in building tissue. Don’t worry about whether or not cooking breaks down enzymes (it does, but so does your body’s own digestion). Your own body WILL break down enzymes present in the food you eat (just like it breaks down the carbohydrates, proteins, and fat that you eat), and it’s exactly because your body breaks them down that you get nutrition from them!<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:21\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Jesper Jesper :\u00a0]<\/div>\n

Sorry. I’d like to know: how dou think e.g. H erectus prepared their food? Feel free to speculate. Cooking can mean many things.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:23\u00a0Jesper<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Richard Wrangham:<\/div>\n

There is no direct archaeological evidence but if Homo erectus ate cooked food, as the anatomical evidence suggests, the cooking methods were presumably pretty simple because they had nothing like pots. So it would be mainly laying roots and meat on coals. By 400000 years ago there is a burnt fire-stick (from Schoningen) that might have been used to hold strips of meat above a fire. Modern hunter-gatherers without pots do things like bury eggs in the hot dirt near a fire, or use upside-down turtle-shells to cook in.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:23\u00a0Richard Wrangham<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Lakshmi Krishnamurthy Lakshmi Krishnamurthy :\u00a0]<\/div>\n

Health is the ratio of nutrient value to calories. Thus, cooked food has more calories as mentioned in earlier comment making it less healthy.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:25\u00a0Lakshmi Krishnamurthy<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

Hi Lakshmi, you NEED a lot of calories per day – around 2,000 or so, which is a lot, if you only have raw foods available. The problem with cooking is not that it increases caloric yield; the problem is that, in modern times, with grocery stores and fridges in most homes, cooking makes too many calories available too easily. So, it is VERY healthy to be able to get a lot of calories from cooked food – say, a cooked steak compared to a raw one, or cooked carrots compared to raw carrots. The problem is in the abuse of cooked foods. But that simply goes to show how effective cooking is to raise caloric content of diets!<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:25\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Richard Lambertsen Richard Lambertsen :\u00a0]<\/div>\n

To Dr. Wrangham’s 2 main routes should be added a reduction in bacteria on foodstuffs that could themselves either cause mortality or render food unpalatable, correct?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:27\u00a0Richard Lambertsen<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Richard Wrangham:<\/div>\n

Yes, reduction in bacteria (and toxins, and macro-parasites) would be beneficial because it increases survival and increases diet breadth. There is even an energetic benefit as well, because it spares the body from the energetic costs of upregulating the immune system to protect against bacteria.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:27\u00a0Richard Wrangham<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Silva Silva :\u00a0]<\/div>\n

Why humans that have the largest heads are precisely those who eat more raw food (the Japanese)?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:29\u00a0Silva<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

Hi Silva, raw fish is easy to eat and can be a great source of calories – in modern times, when it’s very safe to go to the grocery store and buy them! In the wild, eating (raw) fish requires exposing yourself to predators, also interested in the same fish that you want – and who, by the way, would be very happy making a meal out of you! But also, remember that sushi is highly caloric because it uses cooked rice and processed sugar…<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:29\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Seda Seda :\u00a0]<\/div>\n

Could it be that than if we find a more efficient way to get more calories from the food we consume, than do our brains continue growing more?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:33\u00a0Seda<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

Hi Seda, it actually turns out that our body mass and height HAVE been increasing over the last centuries, and that can easily be attributed to, or at least correlated with, an improvement in access to food. But these days? I would say that we already have more calories than we need – just look at the increasing rates of obesity…<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:33\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Sandy Hodges Sandy Hodges :\u00a0]<\/div>\n

Do you think the first fire-maker was descended from an ancestor with a C3 diet, such as A. sediba, or one with a C4 diet, such as A. africanus? Or one with huge grinding teeth and a crest, such as P. boisei? Eating C4, and without the chewing abilities of the robusts to eat roots, much of the A. africanus diet must have been grass seed, as with geladas. Do you think grass seed was cooked by H. erectus?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:35\u00a0Sandy Hodges<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Richard Wrangham:<\/div>\n

Grass seed is difficult to collect without some rather cunning technology (unless you squat like a baboon, which looks difficult for hominins) so I assume grass seeds were not a big part of Homo erectus diet. Root-eating would certainly have helped make the transition easy, because regardless of whether roots were C3 or C4 they could have been easily placed on embers and duly improved. It’s unlikely that H erectus had robusts as ancestors but I could imagine they might have had that a C4 -eating australopith ancestor, maybe eating a lot of papyrus rhizomes and other sedges. Very open question though.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:35\u00a0Richard Wrangham<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From james chua james chua :\u00a0]<\/div>\n

did cooking lead to bigger brain, or bigger brain lead to cooking? the title of this chat is misleading, as it implies causality, while the evidence discussed so far concludes only brain mass and cooked food are correlated.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:36\u00a0james chua<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

Hi James, I would expect that a big enough brain, with enough neurons and hence enough computational capacity, is a requirement for cultural innovations such as cooking. BUT once that biggish brain invents cooking, and if there was an energetic limitation to how much bigger that brain could get on a raw diet, then cooking would lift that limitation and allow that biggish brain to rapidly become larger and larger. That’s why we argue that cooking allowed large brains to go from being a liability (requiring many daily hours of feeding) to being a major asset (allowing greater and greater computational capacity with a very small cost in time investment)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:36\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Silva Silva :\u00a0]<\/div>\n

On average, how many calories a single brain neuron spends per day?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:38\u00a0Silva<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

Our estimate is that each billion neurons costs on average 6 kCal per day. With some 86 billion neurons, then, the human brain alone costs over 500 kCal per day – about 1\/4 the total number of calories that we need per day.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:38\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Ray Ray :\u00a0]<\/div>\n

Hi, did we get to the question of what the best date we have for the taming of fire by H.erectus versus its domesticated use, say, for cooking?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:40\u00a0Ray<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Richard Wrangham:<\/div>\n

The reason for tying Homo erectus to cooking is its anatomy. Newly small teeth indicate a much softer diet than before – and cooking softens food. The shape of the ribcage and the breadth of the pelvis suggest a small total gut size, hence a more digestible diet – again, implying the effects of cooking. And importantly, no such changes happen again later in human evolution. But when humans first started interacting with fire has not been hinted at. Maybe H (A) habilis toyed with fire but did not cook… someone please find a way to test that idea!!!<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:40\u00a0Richard Wrangham<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Natalia Lima Natalia Lima :\u00a0]<\/div>\n

animais tamb\u00e9m muito inteligentes, como alguns mam\u00edferos marinhos, n\u00e3o costumam cozinhar, de onde vem sua inteligencia?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:42\u00a0Natalia Lima<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

[intelligent animals such as marine mammals don’t cook, so where does their intelligence come from?]<\/p>\n

Hi Natalia, our working hypothesis is that “intelligence”, however difficult to measure and compare, is limited mostly by the number of neurons available – which, in turn, is limited by caloric availability. Marine mammals such as dolphins might have numbers of neurons that are comparable to great apes – we don’t know for sure yet, but we’re working on that question. In any case, having a carnivore diet, which is what marine mammals have, certainly provides more calories than a herbivore diet. These animals indeed eat several hundred kilograms of fish per day…<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:42\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Jesper Jesper :\u00a0]<\/div>\n

Hi again. What kind activities would food gathering conflict with? If early humans had to spend nine hours\/24h collecting food? And could that hamper the evolution of bigger brains?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:45\u00a0Jesper<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

Hi Jesper, if you’re intent on gathering food all day long and your life depends on that, you won’t have time to scout for other places to live or hide; socialize and play; teach skills to the young; develop tools, modify your environment, protect yourself. Actually, having to eat nonstop means exposing yourself to predators all day long, too.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:45\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Nate Nate :\u00a0]<\/div>\n

Do humans then have a “weaker” stomach compared to other mammals\/primates due to our long history of cooking? As in, bacteria on raw food, especially meat, would be more dangerous?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:46\u00a0Nate<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Richard Wrangham:<\/div>\n

Interesting question: I have never come across a reasonable answer. People sometimes talk casually about dog stomachs being more acidic, but the pH in human (and I think all monogastric mammal) stomachs is just about the same as in dogs (i.e. in the 1-2 range). I agree that the idea of humans being relatively incompetent at handling toxic or bacterially dangerous foods is compatible with our evolutionary history of being able to protect ourselves by cooking our food, but we know very little about the relative detoxification abilities of human liver (or other organs) vs other mammals. (Apes seem to me less willing to eat toxins than monkeys, so we hominins may also be on an evolutionary line with a history of sensitivity to toxins.)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:46\u00a0Richard Wrangham<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Sylwester Sylwester :\u00a0]<\/div>\n

Why excess of energy after cooked meat was eaten was directed just to increase of brain size?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:50\u00a0Sylwester<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

Hi Sylwester, more energy made available from a cooked diet can in principle be used by both the brain and the rest of the body, but there’s a series of interesting considerations to be made here. First, gram per gram, the brain costs more energy than the body – so the brain would be the first to benefit from greater caloric availability, IF that was limiting to begin with. Second, body size and brain size can be regulated together, but don’t have to; it seems that different species make different investments in increasing body size, or increasing brain size. We argue that, without a cooked diet, energy is limiting, so species are forced to invest the energy available into either a large body or a large brain, but not both.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:50\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Fred Fred :\u00a0]<\/div>\n

Neural tissue is very metabolically expensive so using cooking as a way to increase the caloric content of food is very interesting. I had never heard of that, but I had heard that eating meat was a requirement for a species to evolve brains as large as ours. Any thoughts on how much of our early ancestors diets consisted of meat versus vegetables?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:54\u00a0Fred<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Richard Wrangham:<\/div>\n

The meat vs. veg question is totally unresolved! Recent hunter-gatherers ate least meat near the equator, about 35% of diet, rising to ~100% near the poles. But recent hunter-gatherers are not necessarily good models for our ancestors. They have technology (bows and arrows, and poisons) that made hunting easier; but there again, there may have been more animals in the past. Also, the truly great places for hunter-gatherers to live in may have been those where farmers took over in masses, such as the Nile delta, with terrific plant supplies. So the ‘paleo-diet’ idea that our ancestors were all heavy meat-eaters doesn’t acknowledge the likely large variation in % meat \/ % plant. Anyway, nowadays vegetarians have about the same body mass index as meat-eaters. So meat doesn’t seem to do much to affect energy gain. (But raw-dieters, whether vegetarian or meat-eaters, are much thinner on average than cookivores, whether vegetarian or meat-eaters.) Bottom line: meat is less important than cooking when it comes to energy gain.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:54\u00a0Richard Wrangham<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Mike P Mike P :\u00a0]<\/div>\n

It’s interesting that you mentioned so many other animals have an appetite for cooked food; does this suggest some innate preference for cooking in some animals, or do you think we acquired our taste for cooked food as an artifact of the fact that it was evolutionary beneficial for humans?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:57\u00a0Mike P<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

Hi Mike, I think Richard’s research showing that great apes prefer cooked food over raw food, when given the alternative, is very good evidence that cooked food is inherently preferable – well, tastier is probably the best guess. So that implies that whoever develops cooking will prefer its results over the previous, uncooked alternative, and that would establish cooking as the preferred means to a meal. Bottom line is: inventing cooking would be, in and of itself, enough to make a cooked diet become established.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:57\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Jure Zitnik Jure Zitnik :\u00a0]<\/div>\n

In your opinion, why did some compounds as nitrosamines, polyaromatic hydrocarbons, heterocyclic amines and similar, that are present in charred meat retained their carcinogenic properties or in other words – why haven’t modern humans in a 1 million + years being aquainted with these compounds, developed some sort of protection against their carcenogenic effect?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:58\u00a0Jure Zitnik<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Richard Wrangham:<\/div>\n

Many of those chemicals produced by charring are indeed known to be carcinogenic to lab rodents (and mutagenic in bacteria). But how dangerous they are for humans is unknown in most if not all cases! And some (such as acrylamide) are known NOT to be bad for humans. So it’s possible that humans have adapted biologically to protecting ourselves from those chemicals!!<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a03:58\u00a0Richard Wrangham<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Ray Ray :\u00a0]<\/div>\n

Thanks Richard, how many years ago did H.erecus begin to show these soamitc changes in body structure related to cooking (small teeth, pelvis, ribcage), and they seem to appear about the same time or did they differentially evolve at different times?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a04:00\u00a0Ray<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Richard Wrangham:<\/div>\n

Those somatic changes all came in with Homo erectus. Since the most telling fossils vary in their timing, the range is large (1.58-1.9 million years ago). With more fossils in future, we can find out if some changes happened earlier than others. For now, we cannot tell.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a04:00\u00a0Richard Wrangham<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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[Comment From Elena Elena :\u00a0]<\/div>\n

What about the role of fat in the development of a larger brain?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a04:01\u00a0Elena<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

Fat is very important for brain development: there are fats that build cell membranes all over the body, and not just in neurons, that must come from the diet, because our body cannot produce them; and the brain in particular needs a lot of those fats to build myelin, which is what decreases the time it takes to propagate signals in the brain and thus allows large brains to work fast enough. So eating fat is fundamental, both for adults but even more so for developing babies and children. Which, by the way, I think offers a good explanation for the avidity that kids have for fatty foods. Cooking makes fat more easily available – but then again, having it too easily available becomes a problem in modern life…<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a04:01\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Ann Gibbons:<\/div>\n

Thank you to our two experts, and thanks to our readers\/chatters for your great questions. Sorry we didn’t get to all of them, but this was a great conversation.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a04:02\u00a0Ann Gibbons<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Suzana Herculano-Houzel:<\/div>\n

Thanks to all, it was a pleasure!<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Thursday November 8, 2012\u00a04:03\u00a0Suzana Herculano-Houzel<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n\n\n\n
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Ann Gibbons:<\/div>\n

Join us next week as we talk about how our understanding of crop genomes is changing the food we eat — another food-related chat as we approach Thanksgiving.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"excerpt":{"rendered":"

Our brains consume 20% of our body’s energy when resting compared with 9% in other primates. Scientists have suggested that cooking may have helped humans get that extra energy while spending less time foraging, because cooking effectively predigests food, making … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":172,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5856],"tags":[15568,7022,12723,12720,12721,7050],"class_list":["post-3508","post","type-post","status-publish","format-standard","hentry","category-anth-201","tag-anth-201","tag-brain","tag-brain-evolution","tag-brains","tag-cooking","tag-physical-anthropology"],"_links":{"self":[{"href":"https:\/\/blogs.nwic.edu\/briansblog\/wp-json\/wp\/v2\/posts\/3508","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.nwic.edu\/briansblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.nwic.edu\/briansblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.nwic.edu\/briansblog\/wp-json\/wp\/v2\/users\/172"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.nwic.edu\/briansblog\/wp-json\/wp\/v2\/comments?post=3508"}],"version-history":[{"count":0,"href":"https:\/\/blogs.nwic.edu\/briansblog\/wp-json\/wp\/v2\/posts\/3508\/revisions"}],"wp:attachment":[{"href":"https:\/\/blogs.nwic.edu\/briansblog\/wp-json\/wp\/v2\/media?parent=3508"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.nwic.edu\/briansblog\/wp-json\/wp\/v2\/categories?post=3508"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.nwic.edu\/briansblog\/wp-json\/wp\/v2\/tags?post=3508"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}