Richard Wrangham – Rediscovering Fire

August 27, 2010

This is a show about evolution—but not, for once, about the evolution wars. Instead, it concerns one of the most intriguing ideas to emerge in quite some time about the evolution of humans.

In his much discussed book Catching Fire: How Cooking Made Us Human, Harvard anthropologist Richard Wrangham argues that we’ve been ignoring a critical catalyst in the creation of our species—a little technology called cooking.

Cooking was the game changer, says Wrangham. It upended everything. It altered how we obtained energy, which in turn morphed our anatomy and cranial capacity. Cooking even changed how we came to spend our days, and divide labor between the sexes.

According to Wrangham, learning to cook therefore ranks among the most important things that ever happened to our ancestors. In this episode of Point of Inquiry, he discusses why cooking was so pivotal—and why its role has so long been overlooked.

Richard Wrangham is the Ruth Moore professor of biological anthropology at Harvard University, and the author, with Dale Peterson, of Demonic Males: Apes and the Origins of Human Violence. His new book is Catching Fire: How Cooking Made Us Human.

Today’s show is brought to you by Audible. Please visit Audible podcast dot com slash point to get a free audio book download. This is Point of Inquiry for Friday, August 27, 2010. 

Welcome to Point of Inquiry. I’m Chris Mooney. Point of inquiry is the radio show and podcast of the Center for Inquiry, a think tank advancing reason, science and secular values in public affairs. And at the grassroots. Before beginning our regular program, I want to remind you that point of inquiry is sponsored by audible dot com. Audible is the Web’s leading provider of spoken audio, entertainment information and educational programing. I’m still staggered by the 75000 books that Audible lets you download to your computer, your iPod or a C.D.. Let’s say you’re a person who exercises. You need to work off all those buffalo wings. Well, imagine how great it would be to have your favorite science book read off in your ears while you jog or walk or go swing it on that elliptical machine, because, of course, Audible is very strong on science content and went and checked. And they have the book featured on our show today. More on that in a minute. But it’s kind of perfect, don’t you think? You listen to the show and then you zip on over to the following Web site, audible podcasts, dot com slash point and get your free book download. Our regular listeners know a great deal about evolution and especially about why we defend its teaching. This show is about evolution, but it’s a little different. It’s not about the evolution wars. It’s about one of the most intriguing new ideas to emerge in quite some time about the evolution of humans in as much discussed book Catching Fire How Cooking Made US Human. Harvard anthropologist Richard Wrangham argues that we’ve been missing one of the most important catalysts that made us who we are. Who’d have thunk it was cooking? That was the game changer, if Wrangham is right. It upended everything. It altered how we obtained energy. And that in turn morphed our anatomy and cranial capacity and even how we spent our days. The very rhythms of our lives. According to Wrangham, cooking ranks among the most important things that ever happened to our ancestors. In the next half hour, we’re gonna hear why this is so and why it has so long been overlooked. Richard Wrangham is the Ruth Moore professor of biological anthropology at Harvard University. He studies chimpanzees and their behavior in Uganda and is the author with Dale Peterson of Daemonic Males. Apes and the Origin of Human Violence. His new book and the subject of our show is Catching Fire How Cooking Made US Human. 

Richard Wrangham welcomed the point of inquiry. 

Hey, great to be here. Thanks. 

I’ve wanted to have you on the show, actually, ever since I interviewed you for the BBC about your book, Catching Fire How Cooking Made US Human. You were nominated for the Samuel Johnson Prize in the U.K. It’s a big nonfiction award. And I guess you didn’t win. But the book has had quite a good run, has it not? 

Yeah, it’s been terrific. You know, I found it interesting that one of the criticisms that they said was responsible for not winning was the fact that it’s it’s still not definitely accepted by scientists. The notion that cooking made us human, which is interesting because I find other people saying, hey, it’s so obvious, how come no one’s ever seen this before? 

That was my reaction in reading the book. And it’s really interesting. This started out as an academic paper and you decided to just go public in popular publishing. Can you tell us a bit more about where the idea came from? 

Well, it started with me about twelve years ago. I have always been studying chimpanzees for the last 30, 40 years in the wild. And I was always interested in that diet. 

And when I am teaching at Harvard, I have the responsibility of thinking about human evolution. So I compare humans and chimpanzees. And it was a familiar feature for me while following chimpanzees that. To eat what they ate was not satisfying because you could quite often eat enough to assuage your hunger. But nevertheless, it was very difficult to really feel satisfied after eating wild chimpanzee foods. And that was the observation that began for me. A road of inquiry that said, just how important is it to be able to sit down and have roast potatoes and roast meat and pasta at the end of the day? 

What exactly do chimps eat? 

Something like 60 percent of their diet is fruit. And not so terrific. It sounds oranges, apples, bananas. Hey, no problem with that. And a lot of people today who have either a special diet eating just fruit, but the foods that you find in the wild are not like the ones that we get in our supermarkets because they are much more fibrous. They tend to be much drier, that much stronger tasting otherwise full of natural plant toxins. And they have much less sugar. And they are therefore rarely satisfying as anything that you can get in a regular American town. Now, when they finished eating their fruits and they can’t find anything else, then they tend to eat what you might think of as holiday things. But it’s gained its own like lettuce. It’s much tougher. It’s more like the kind of leaves that you find in a hedge or by the roadside. They are service of the leaves of sweet potatoes, for instance. Quite difficult for humans to tolerate. 

And this experience of sort of self experimentation, eating chimp diets and so forth, eventually got you on to do the general thesis, which is, as you write in the book, we humans are cooking apes, the creatures of the flame. So let’s let’s get into the argument. Can you take us a little bit through our evolutionary history and show where cooking shows up? 

Yeah, I mean, for me, the story begins with thinking about how well or poorly humans do when eating food that is raw. And of course, there are many people who nowadays like to eat food that is raw for various kinds of philosophical or health related reasons. And they might be surprised to hear or I’m not going to say which is, but why not adapt to eating our food raw? But the reason we can say this is that even on the best, highest quality kind of raw food diet, what you find is that people have a chronic energy shortage. They tend to lose quite a lot of weight. And here’s the most dramatic thing. Half the women in the best study that has been done of this turned out to not be able to have a baby. They stopped menstruating when eating a raw food diet. And since that’s happening on the best possible quality of the diet, that means that in an ordinary Hunter-Gatherer world, you couldn’t possibly survive on raw food. Then the question is, well, what’s special about humans that makes them different from every other animal? And the answer is pretty clear. We are in the primate order. There are some 300 species of primates alongside us in our order. And we have the smallest teeth in relation to body size of any of those species. And the smallest guts, intestinal systems of any other species. And it’s pretty clear why we have that. Because animals that have high quality diets have smaller guts. Makes sense. You don’t need such big processing tissues. If you’re eating a relatively high quality diet. Well, we have the highest quality diet of all. And we have the smallest guts and smallest teeth of all. And then the question is, when did we get these? And the answer is pretty clear. It’s around two million years ago. Just this side, about one point eight, one point nine million years ago is when Homo erectus evolved. And they had the small teeth and the small guts that are characteristic of the human lineage. And so for that reason, among others, I think that we can now say that this cooking habit with a signature feature of the human diet goes all the way back to almost two million years ago. 

And this is part of your argument. That is that is very different, is that this requires you to place the discovery of fire much farther back in time than others have. Is that correct? 

Well, that is right, Chris. And the reason that there is a problem with the received wisdom is that archeologists find no directly supported evidence of the control of fire beyond about 800000 years ago. Now, you know, my response to that observation is, well, the further back you go in time than the less likely it is that any residues of fire will be detectable. And everyone agrees that that’s true. So the question is, can we refine the state of archeology to be able to say definitely yes or definitely no? When fire was first controlled? 

And I think that’s going to be a fascinating area of investigation over the next decade or two in this argument, cooking turns out to be a fairly dramatic invention or even technology created by our ancestors. And then this technology in turn in a kind of feedback loop creates us. How many other technologies are there that humans have created that have had that big of a transformative influence? It’s got to be a select few. 

I think you’re right to direct attention to just how big this question is, because traditionally people have thought of cooking as something that is very nice. It gives flavor to food. It means the food’s a bit safer to eat because it gets rid of some of the poisons and bacteria and so on, but not as transforming. Whereas I’m saying this is a huge, huge change because what cooking does in addition to all those things, is it gives us energy and there’s really no doubt about this. Cooking quite clearly increases substantially the amount of energy we get from our food. And because energy is the rarest and most valuable resource in nature. It’s a resource that determines how successful an individual is in their own personal reproductive efforts and in their survival. It determines how well a population, a species does. That means that cooking is huge now simply because it increases the amount of energy available. That means that those individuals who first cooked food have survived better and have more babies and so on. But in addition to the whole thing, it makes your food soft. 

And that means not only that you can afford to have small teeth, but that you can eat your food incredibly quickly compared to a chimpanzee. Here’s an example. The chimpanzee spends around half the day just chewing out the first chimpanzees I studied. They spend actually more than that between six and seven hours a day. Just sharing their food of humans did that. We’d have a completely different way of life. But actually we only spend an hour or less chewing our food after that is relaxing with others over the meal. So there are all these immense changes that happen with cooking. And the short story is that they were big enough to change a prehuman apelike form into a human. 

I think they were responsible for giving us the basic anatomy that is recognizable in the first full member of our genus Homo erectus. 

And you point out also in the book that Darwin did lightly touch upon this subject, cooking and fire, but not in any way that gave it much credit for having a big impact. Why do you think that Darwin and his successors will that includes all of your your peers and your fellow scholars didn’t credit this innovation in this way before? 

I think that the great and interesting question. There are also two kinds of answers. I mean, in some ways it’s tempting to think that, well, cooking is something that women do and therefore it’s not so important. People have traditionally focused on male activities and in human evolution. As for Darwin himself, he certainly appreciated the importance of fire. He said it was the discovery of the control of fire was probably the most important event in human evolution compared to anything except language, the acquisition of language. But one thing that I think is a clue about this is that Darwin clearly was thinking about the control of fire as having emerged during the period when humans were already human. A primitive kind of human looked like us. Same sort of height, the same body shape, just a little bit smaller brained. And many people subsequently have had the same thought that probably fire was first controlled by a member of the human lineage. Well, if that was the case, then it wouldn’t have had much evolutionary impact because a human did it and then carried on being human. And it’s only when you take that leap of imagination to say is it possible that it was a prehuman that invented the control of fire, that you see just how potent its effects might have been. So I think the most important factor that has prevented us from seeing the importance of cooking so far has been just the assumption that it couldn’t have happened very early. But once you think of it, it’s happening early. Then it opens all sorts of windows to fascinating. 

Prior to your work, anthropologists and evolutionary biologists did have another theory, which is not been disproven, rather, it sits next to yours. Now, I guess, which is that it was learning to hunt and eating meat that centrally drove evolution. So what is the relation between those two ideas? 

Yeah, well, I’m absolutely sure that meat eating remains a very important contribution to the human evolutionary story. We see it first in evidence from Ethiopia about 2.5 million years ago of australopithecines probably are prehuman ancestors, both cutting meat off bones. You see this in fossil bones that have got cut marks always in the right place to pick the meat off. And in the production of Flakes of Stone, that would have acted as very effective lives. And then ever since then, there’s been very consistent evidence that our ancestors have been importantly directed towards getting meat. 

And when we look nowadays at Hunter gathers meat, eating is a very important part of our lives. So here’s the story. It looks as though meat eating began at least two and a half million years ago, probably a bit earlier. And as I say, the evidence for cooking is just this side of two millennia. So probably what happened was that meat eating was the first big influence which created a higher quality diet for our ancestors, starting to in half in years ago or earlier. And then for several hundred thousand years, they were eating their meat raw and then cooking came in. I think it sealed the deal, as it were. 

It increased the amount of energy they were getting from their food. It contributed further towards many of the kinds of social consequences of eating these lumps of meat, which would have required individuals to cooperate, to be tolerant of each other, to be patient as they cut it up and so on. So there’s the story. Meeting first, then cooking. And then you’ve got a major step towards the evolution of humans. 

I want to get into those social consequences more. First, let me alert our listeners. Richard, Rangoon’s book, Catching Fire How Cooking Made US Human, is available through our Web site. Point of inquiry, dot org. Actually, a bit of a philosophical point that I want to try out with you about the book. Essentially, it seems in you what you’re doing in a popular book that’s also trying to advance scientific knowledge is making a sort of weight of the evidence, circumstantial argument, pulling a lot of evidence from a lot of different places and synthesizing and using a popular book to do. That’s kind of like what Richard Dawkins did in The Selfish Gene. Do you think there’s a need in science for more of these attempts at big picture painting? 

I think to judge from the response, which, you know, has been delightfully favorable. There is an opportunity for scientists to do this more. I think that’s difficult for us because there are tremendous pressures on researchers to be very specialized and really good at focusing in on a relatively narrow area of expertize, which makes them the best in the world. And once you start becoming more of a generalist and picking all the evidence from diverse sources, then of course there’s a tradeoff. But if you can do it, I think there are tremendous rewards to be had. I mean, this particular case, no, I think it’s just amazing that a topic that everyone you have started, a nonscientist, an interested in one way or another cooking has been given incredible little attention because it kind of falls in the cracks between traditional sciences. And I’m sure there must be many other areas like that, which, if you focus on them, will be enormously revealing and exciting. 

That’s really intriguing because as you say, I guess there’s sort of the evolutionary scientists and what was the academic specialty that actually focused on cooking that didn’t talk to evolutionary biologists or anthropologists? It was some sort of social history approach or what was it? 

Well, I was thinking more than nutritional science. Oh, I see. I mean, you’re you’re right about the social history, but. But in nutritional science, it’s particularly dramatic. And as I noted my book, you cannot even find as an ordinary member of the public or even actually as an inquiring scientist, what is the difference in calories when you cook food from when you eat it raw? That doesn’t reflect the idea that nutritionists challenge the notion that cooking increases the amount of calories, but it does show that there’s been extremely little scientific work on finding out how big the effect is on quantifying it. And, you know, I as a field primatologist who studies behavior, chimpanzees in the wild, ended up doing experiments with nutritional scientists like Stephen Ziko to try and. Yes, in a quantified way, how big the effect of cooking was. So, you know, there’s an enormous gap. And one of the big areas in which I think we need to actually do something about it in a practical way is to get the food labeling system changed, to acknowledge for people the difference between eating food cooked on eating raw. 

I find it staggering this last point, because there’s so much popular interest in diet and precisely what you eat and how to get the figure that you want. I mean, people sell books that, you know, sell hundreds of thousands or millions of copies about diet. And yet this little point. What’s the difference between cooked food, raw food in terms of how it affects you calorically is just it’s just a gap. I find that amazing. 

Yes. And it’s part of a larger area. I mean, it’s big enough as it is, but it’s part of a larger failure on the part of nutritional scientists to draw attention to the effect of food processing. So cooking is one kind of food processing. But there are others, such as the system by which you reduce the size of the particle. I mean, if you take a whole grain bread, you have much bigger particles in it than you do in white bread. And the result is going to be that humans will get a higher number of calories out of the white bread than out of the wholegrain bread. Nobody tells us this. You will not find this in the food labeling system or even in the back story. And yet the paper just been published about two months ago by, say, de Boer, who has shown that if you feed sandwiches, a process cheese on white bread compared to whole cheese and whole grain bread, there’s about a 10 percent difference. And the net number of calories and the result, of course, is that you are going to get relatively fat if you eat the processed cheese and white bread compared to the unprocessed forms. Well, you know, we need to be told us, know where this leads. 

And I’ve talked to you about this before. This leads the idea that there is out there in the dietary space and evolutionarily based diet, which is different from all the recommendations that people currently get. 

Yes. And, of course, the kind of diet that you’re going to recommend depends on the particular eater. So if you are thin, then you want to eat more cooked and more processed food. If you want to get fatter, if you are fat and you want to get thinner, then you want to go in the opposite direction. These are relatively simple principles, but they need to be spelled out and ideally, of course, they need to be quantified. Just how big all these effects are. Are we talking about 10 percent, 20 percent, 30 percent difference in how many calories you’re getting with different levels of processing? At the moment, it’s the guests, with the exception of just a few studies. So for that, there’s a tremendous amount waiting to be done there to to encourage people to be able to get a diet that is better suited to their particular needs. 

There’s one question I have to raise here being a sort of fantastic sushi eater. Where does sushi fit into the spectrum? I mean, here’s a raw food. But I feel like I get fat eating so much. 

Well, but the thing about sushi is that it is it’s cold, but there’s a lot of cooked rice in it. And so, you know, you’ve got your raw seafood component. But the path that is going to be responsible for your feeling full after it is is going to be the cooked rice as much as anything. 

There you go. So we should be seeing the sashimi if we want to lose weight. 

There you go. Right. 

Let me go back actually to to a point that we didn’t get into. This is somewhat controversial. You argue that a gender division of labor in which women do the cooking for men evolved because of the practice of cooking itself. So cooking leads to marriage and it leads to patriarchy. Can you explain the logic there? 

Yes. I mean, this is definitely more speculative area. 

We can’t go into experiments on this, but I think it fits the data, particularly on the patterns of marriage and subsistence in small-scale societies like hunters and gatherers and small-scale farmers. It fits us particularly well. So here’s the story. Once we cook, the way in which our food is distributed for us is forever changed because you have a fire. Food is sitting on the fire. The as it were, the meat and potatoes. And that means that the food becomes easy to steal. It’s in this deal because the food is sitting there while it’s getting ready. So the smoke coming off, it’s easy, rather, to see where it is. And the cook has to be patient because obviously the whole point about cooking is and has to be ready after 20 minutes, half an hour, an hour, whatever it is. So that means that a socially vulnerable person is in a position where they might have their food taken from them. Now, the way I think about it is that what has happened in evolutionary time. Is that we have evolved a social arrangement in which women who are vulnerable to the potential of thievery of bachelors and other men have developed a social relationship, which we call a marriage with a particular man who will protect her and the way in which your protector is not by literally standing guard near her fire. But once you’ve got language, the way it works is that she can tell him, look, that lovey bachelor came in, took some of my food when I wasn’t looking or whatever. She will then tell her husband and a husband will then tell the rest of the men and the rest of the men will say, this has got to stop and they may beat the bachelor and they may exile him. And in the worst case, they might even execute him. 

And those sorts of things are found in traditional societies, those sorts of responses. Now, meanwhile, what does the husband get out of this? 

Well, the husband gets a fantastic deal, which is that he can spend all day doing what he wants. And it might be hunting for meat. It might be looking for honey, it might be looking for a girlfriend, might be sitting under a tree in the shade chatting to his mates. It might be going to war. Whatever he’s doing, he knows that he can come back in the evening and he can find a cooked meal waiting for him. And so I think of the cooking as enabling this system. The reason it enables is because it’s cooking. That means that the food can be eaten so fast in such a short time that it’s worthwhile for a man to come back in the evening. And he knows that in 40 minutes he’s got fifteen hundred calories in him. 

So once you get cooking, the man can afford to go off and then come back and and that’s his part of the sexual division of labor. And then he is protecting a woman. But the deal that he’s making with the woman, as it were, is she has to cook for him. So this is not a particularly pretty picture. And I thought what I advocate that I’m not sort of trying to suggest this is how life ought to be. And in fact, nowadays we’re getting away from this. And that’s partly partly because of the ease of the food production system nowadays. It’s easy for a man to pick something out of the fridge, easy for a woman to spend a little time cooking because of fast food restaurants or or just packaged food in supermarkets. And so the way I see it, this is sort of ancient imposition of the food system on the marriage system, which is now going to lead in new directions. And we’re seeing new directions to marriage all the time. 

So is one implication of this analysis that, you know, and I think maybe this is borne out. People actually men especially gain more weight when they’re married? 

Yes, I think so. And, you know, I don’t know how far to take this. I think it’s an interesting area of psychological inquiry. But, yeah, there are some hints that women really do feel very concerned about making sure their husbands are well-fed and that if they perceive that another woman is feeding her husband, then they feel very alarmed at Marling’s. They want to do is to make sure that the husband is is really enjoying his food. And so easy enough of a man to, as you say, get more bulk on them once they are married. And they’re the sort of flipside of that is in small scale societies, bachelors tend to be sort of thin and impoverished creatures because they’ve got nowhere to feed them. And either they cook for themselves, in which case they have to spend time doing that and therefore can’t do all the things that are supposed to be manly in that particular society, or they just go hungry and generally they tend to go hungry. I think you see that a little bit in our own society today. 

Well, I’d like to again alert our listeners that Richard Wrangham is book Catching Fire How Cooking Made US Human is available through our website Point of Inquiry dot org. Just a couple closing questions. Let’s set your book in your argument in the context of the United States, whereas you know very well the theory of evolution itself is often viewed with great skepticism. Do you detect any of that in the response to the argument you’re making? 

You know, so far I have not had that. And I don’t know whether that’s because it hasn’t reached the anti evolutionists enough. But you know, what I’d like to think is that this is an argument that is so rooted in everyday experience that it doesn’t seem too threatening in terms of its evolutionary implications. 

That may well be the case or it may be that perhaps putting together something, Poppy, that everybody cares about cooking with evolution, evolutionary thinking is a really good thing for evolutionary thinking, which has had its, you know, sort of been attacked so much. 

This makes it accessible again when all of the people attacking it for so long have made it so alien to many Americans. 

Well, it’s a lovely thought. And if I felt that was true, I’d be delighted. It’s quite. That evolutionary thinking has to be a part of our future. Whether we’re talking about medical adaptations or understanding the way our bodies work, and the sooner we can get rid of this fear of evolutionary thinking, the better for all. 

And I think you may be contributing quite a bit to that. Sir Richard Wrangham, it’s been a pleasure to have you on point of inquiry. Best of luck with the book. Thank you so much, Chris. 

I want to thank you for listening to this episode of Point of Inquiry to get involved in a discussion about Richard Rangoon’s book Catching Fire. Be sure to visit our online forums by going to Center for Inquiry. Dot net slash forums, then clicking on point of inquiry. Also, don’t forget to head on over to Audible podcast dot com slash point for your free audio book download. If you’d like, Catching Fire could be your selection. You can also order a copy of the book through our website Point of Inquiry dot org. The views expressed on point of inquiry aren’t necessarily the views of the Center for Inquiry, nor of its affiliated organizations. Questions and comments on today’s show can be sent to feedback at point of inquiry dot org. 

Point of inquiry is produced by Adam, Isaac and amrs New York, and our music is composed by Emmy Award winning Michael Wailin. Today’s show also featured contributions from Debbie Goddard. I’m your host Chris Mooney. 

Chris Mooney