A conversation with the Harvard primatologist.

Question: What are the two most fascinating things about human evolution yet to be explored? 

Richard Wrangham: How it is that a pre-human ape became a human. And it's a question that Darwin had no idea about really, and that we've had only some rather simple ideas about until recently, and I think we still have a long way to go. And until we have a sense of the continuity in an evolutionary sense and the biological factor responsible for something like a Chimpanzee standing upright, becoming what we are today, then we will always have this sense of anthropocentrism. We will always feel just a little bit divorced from the rest of the universe. And that's one big question. 

I think another huge question is about the evolution of human nature with respect to the biggest use of cooperation, processiality, altruism, and on the other hand, violence, aggression, a willingness to kill. We are an unusual species because we have such an extraordinary mix of these two aspects. We show them both to extremes. We're amazingly more cooperative than almost any other species and we're extraordinarily destructive compared to most species. And grappling with the extent to which that is a product of culture and biology and to the extent of why we should have biological position to go in both of those directions remains one of the huge questions. Which again, is something, of course, that is hard to reconcile with the rest of nature in many ways and for that reason, people resort to religion and they resort to all sorts of naturalistic point of views, strange belief systems to grapple with the question of good and evil. 

Question: Are humans predisposed to behave violently? 

Richard Wrangham: Well, to talk about inherent aggression in us sets off alarm bells for some people because it sounds biologically determinist, it sounds pessimistic. So, I wouldn't want to quite put it in that term. But, I do think that there's all sorts of evidence that humans have got a predisposition to behave with violence in certain contexts, that yes. And it's a great thing to be aware of it and the more we're aware of it, then the more we can do about it. 

You know, it has nothing to do with whether or not one is optimistic, or pessimistic about the future. And I'm a firm believer in the fact that war is not a necessary feature of human life and that there has been a rather impressive decline in the amount of killing that humans as a species do over the last centuries and millennia, and that the future can be expected to be increasingly rosy. But none of that is to deny that within the human heart there is a dangerous side. 

Question: How can we overcome this? 

Richard Wrangham: We can carry on doing the kinds of things we are doing, which is to think deeply and carefully about anticipating violence. About setting up institutional systems that enable us to anticipate when there is a threat of genocide in the country, when there are threats of war between states and for other states to be prepared to intervene. I mean the great thing nowadays is that, whereas in recent decades and centuries, when two countries declared war on each other, the others just stood by and watched. Nowadays, everyone is very scared and alarmed about it. And doesn't want this to happen and there is intervention just flowing all over the place. You know, we try to get involved in Darfur, we try to get involved in the Congo, we try to get involved in Bosnia. And as a result, things change. 

Question: Where are we headed now in terms of aggression and war? 

Richard Wrangham: The size of the groups that are political units has just been growing, not exactly steadily with leaps and drops, but have been growing over the millennia. And surely the way in which the human species is ultimately heading is towards a single group. And to me one of the great questions of the future is whether or not that group will be achieved by unanimous pooling of the decision to unite into conquering some of the great problems of the world, such as climate change, or food shortage, or the threat of aggression, or whether or not the gloomy view would be that the single united human group will be achieved by domination. And I think that's, on the whole, unlikely. 

I think that the great value of the technological advances that have been happening in the last decades is that people communicate enormously better than they used to so that when there is a problem in Fiji, then the whole of the rest of the world knows about it. When there is an earthquake in Haiti, then within a few hours, everybody in the world knows about it and is rushing to help. And one of the consequences of that sort of communication, or ability, is that the dispossessed get a little bit more power. 

So, in the general sense, I feel that the world is becoming increasingly democratic. There are more voices to those that traditionally had very little power, indeed. And that's the kind of dynamic that will help avert a hegemonic move towards a single world government, and instead something more like what's happened in Europe, with countries just saying, it makes sense for us to work together. 

Question: Why did you become interested in working with Chimpanzees? 

Richard Wrangham: Well, in 1970, I was a newly minted undergraduate looking for a research project and I discovered about the Chimpanzee project and at that time, I was much more interested in questions about what is responsible for species differences in social organization than I was in anything in particular about close relatives of humans. I wasn't particularly interested in Chimpanzees as a model, or a close relative of humans but simply because they're a fascinating species and it was a very lucky time because Jane Goodall was looking for people to help her in her study, so I wrote to her and in three months later, I think I was in Western Tanzania at her site in Gumby. 

Question: What was it like working with Jane Goodall? 

Richard Wrangham: She had a young son, Grub, who was then, something like five or six-years-old, and so she was not spending much time at this field site. She was living mostly in another place in Tanzania in Serengeti National Park, or on the edge of it. And so, her direct input was very much producing a few great observations on how to behave and then just letting you run. So, she would say things like, "By all means, connect your data systematically, but if you see something really interesting, make sure you go for that instead of sticking to your formula." And she brought a tremendous sense of intimacy and liveliness to the discussion of the Chimpanzees when she would visit every few months because she was just fascinated with the lives of the individuals. And for people, like myself, who had been trained in an ordinary way in university life where our concern was with enlarging the sample sizes and making sure that you have everything organized in a research design that allows statistical testing, and so on. The frank focus on what particular individual had done and how they seemed to feel about others was refreshing, conceptually enlarging, somewhat brave, so all very good challenge and complementary perspective to a more orthodox training. 

Question: What did you discover? 

Richard Wrangham: Well, I did my PhD on the feeding behavior of Chimpanzees and I think that was a rather nice thing to be able to study because life is, in many ways, a search energy and Chimpanzees, just like any other species, have as a primary concern just finding calories. And that is a key to understanding an enormous range of behaviors. 

So, as I walked about with chimpanzees, I was seeing how they were interfacing with the forest in a very, very direct way and seeing how they had their behavior shaped by this primal need. So, the size of the groups that they were traveling in, the distance they were traveling per day, the amount of energy they had for social interactions, the concern they had for exciting things like hunting monkeys, or having sex, or going on border patrols to defend their areas. All of these were constrained and influenced very, very strongly by their root relationship with food. And unless you understand that, you don't understand the way animals experience the wild. And I think also, you don't understand the way that our ancestors only a few thousand years ago responded to the wild. 

So, it's a wonderful foundation for thinking about the influence of the natural world on the more complex, richer forms of social behavior. 

Question: Have the any of the results of your research surprised you? 

Richard Wrangham: So, one of the things that happens with chimpanzees is that they use sticks, a bit like toys. And it turns out that the juvenile females use sticks in a way that I suppose is rather unfamiliar to us, but basically they just carry them around. They'll just break off a stick and they'll carry it on their back, on their tummy, keep it with them, sit with it while they're feeding. And then after a few hours, sometimes after a few minutes, let it go. 

Males will break off a stick and then guess what males will do with it? They'll use it to hit others or throw it at others. So, it's kind of like kids in the playground. You know, they're not allowed any guns, they're not allowed any dolls and what happens? The boys will pick up a rock and use it as a gun, and the girls may pick up a gun and use it as a doll, who knows. 

Well this inspiration to a study in which an undergraduate, Rob Tennyson, has tested what a baby does to play with a balloon both before and after it sees somebody hitting the balloon. So, this was a kind of shock because, first of all, it turns out that if you allow a baby to play with a balloon and then allow it to watch both men hitting a balloon, women hitting a balloon, men cradling a balloon, men cradling a balloon, then what the babies do is change their behavior in one particular way. Girls don't change their behavior, they hit the balloon before watching, they hit the balloon after watching, no difference. The boys hit the balloon before watching, but after watching, then it turns out they hit the balloon twice as much. 

And what are they watching? Well both boys and girls tend to watch hitting more than cradling because hitting is just a little bit more exciting, more interesting. But here's the amazing thing. The boys watched the man hitting and the more they watched the man hitting, the more they hit. And the girls watched the woman hitting, and the more they watched the woman hitting, the more they hit. So, this is domestic violence model. At six months old, these are long preverbal; these little babies are picking up on their own gender and responding by modeling their behavior on their gender. 

So, it's a wonderful interaction to biology and culture because the boys are hitting more than the girls as a consequence of watching, and so that's something from within. That's some biological system that is causing that. And yet they're both being socialized because they're both saying, "Hey, mommy or daddy is doing the hitting; I'm going to do some hitting too." It means that even at six months, you've got to be careful about what you allow your babies to watch. 

Question: How would women holding more positions of power influence the climate of war in society? 

Richard Wrangham: Well, I mean, when you look at primates and when you look at humans, it's very clear that in a majority of species, particularly first related to us, males are in many ways more aggressive then females. And this aggression plays out in a particular way, so if you just talk about gossip, if you just talk about the relatively low level kinds of aggressiveness, actually there's no difference between men and women. It's when the aggression is really costly to the victim. It's when, for instance, in car accidents, call them accidents or call them something else, where the car has been used as a weapon against somebody else. Men are far more likely to be the drivers, per million miles driven, whereas, in minor accidents, men and women are equally likely. 

So, there's all sorts of evidence that men are more violent than women and this is surely significant when we think about the high level interactions that occur in interstate conflict. So, if you look at the leadership styles of men and women, you find that women are more thoughtful about the outcome of potential conflict, they are better at taking the perspective of the opponent; they are less likely to be purely ego-driven, simply wanting to be superior to the other side. Experiments show this and analyses of particular interactions show this. 

I think that when in October, 2008, Rwanda became the first country in the history of the world to have more women than men in its national legislative body, in its parliament. That was a great move forward. And wouldn't it be wonderful if we get more women sharing with men the decisions that are so critical to all of us about power relationships because not to say that women will necessarily always be peaceful, not to say that they won't, on occasion, be just as bloody and destructive in their decisions as men might be, but it is going to tilt the balance towards a very often, more reasoned and optimistic outcome, I think. 

Question: Why aren’t women there yet? 

Richard Wrangham: I do think that people have not paid enough attention in general in thinking about sex role differentiations to some very elemental thing about our domestic lives. And so this relates to the issue of cooking. The fact is, that all the way around the world, in every culture, except modern urban industrial society, you can absolutely predict that women are going to be doing the cooking for men. And the significance of women cooking for men is that during the day, a woman is bound to the stove. Now, you can say it's because she has small children anyway, and to some extent that may be a contributor. But for whatever reason, the fact is that in essentially every society women are responsible for the cooking, whereas, the men are free to go off during the day and do something, nowadays, to go into being a professional, becoming a professional politician, and then be fed by their wives in the evening. And of course, in the era of fast food and easy meals picked up at the supermarket, it is a lot easier for men and women to share the domestic tasks and in urban industrial societies, that's what very often happens. Sometimes you get a reversal in which men cook for women. 

But, I'm sure a huge sociological momentum which has maintained this tradition of women being domestic and men going off and being free to develop their own professions. So, I think that's just as important as any kind of tendency to do with men being more ambitious for the rewards of professional work. And the point about the cooking, since it's old news, but I think what's interesting about it is, only recently we started thinking about the fact that this really makes humans very different from our close relatives. Because our close relatives, you never get women cooking for men, as it work. They don't cook for anybody, of course. And so here we have a radical new kind of system, which I think has enlarged the potential for patriarchal domination by men of women. Once you have the cooking system with the household economy as we have it today, then the result is you have this huge freedom for men and not for women, and it exaggerates any kind of previous tendencies for sexually dimorph -- sexually different sex roles. 

Question: How would women handle leadership positions differently than men? 

Richard Wrangham: I think there are big differences between men and women that conform to something that we see in our post relatives. If you look at the things that chimpanzees compete over, then what it comes down to is that the females tend to complete over sensible things, that is to say, food, safety for their offspring, a safe place to be. They will fight over those things. Males tend to fight over nothing. Males tend to fight over just a look. Over just status, over just whether or not the other guy gave the appropriate signal of subordinancy. If he didn't, I'm going to fight him. And this is, of course, incredibly like what you see in humans. So in urban gangs, whether they are in Norway, or Los Angeles, or the Philippines, I mean, it's a human thing, it's not a race thing. Then what you see there in a kind of anarchic world because you have young kids, on their own, on the streets, nobody being able to protect them, they’ve got to look after themselves, then a look really matters and its the guys, its the young men for whom respect is just phenomenally important, and if they don't get it, then what do they do, they resort to aggression. 

Now, why is it that it should matter so much for men that respect be given to them? Well because respect is a predictor of their ability to get the resources when the crunch time comes. So, it's kind of setting up in advance who is going to get access to the key things; the food, the women, the weapons, whatever it is. 

So, yes, I think that carries on in sort of in some ways, you could say a ridiculous way into the adult world of modern sociopolitical complexity. We bring with us some atavistic tendencies from our ape past. 

Question: Why are there so many people in the U.S. who don’t believe in evolution? 

Richard Wrangham: The capacity -- no, the tendency to accept evolutionary theory is, of course, not just judged on the merits of evolutionary theory, it's judge because it is as seen as being in opposition to religious belief. And religious belief carries with it not just the belief itself in a particular set of facts and ideas, but all of the huge social and political associations. So, in the United States, if you don't believe in evolutionary theory, or if you do believe in evolutionary theory, then it means it's harder for you to commit yourself to a religious group that has huge significance. And so I think the answer to why it is that evolutionary theory is difficult for people in the states to believe is that religious systems are so incredibly prevalent. And why is that? I guess I think it has something to do with the United States being a rural country and there's a lot of association between rural living and the importance of religious systems. You see it in the Middle East, you see it in Iran, I suspect that as the world becomes more urbanized, you know, we've just past the point where 50% of the world's population live in cities, I think as this tendency increases, probably the importance of religious belief systems will start declining, or will continue to decline and that one of the consequences will be that there will be increasing willingness to accept even those aspects of science that challenge religious beliefs. 

Question: How does cooking play a part in evolution? 

Richard Wrangham: Well, cooking is a huge influence on the availability of energy. And ultimately, cooking does much more than provide energy, but the first great thing it does, which has not amazingly been appreciated until very recently, is that cooking gives us more energy than eating our food raw. And when our ancestors first learned to cook, then the great huge initial impact would have been that they got so much more energy that they would have had more babies than they had before. And their babies were to survive better, and the adults were to survive better simply because they were able to eat more and have more regular menstrual cycles and put more energy in the immune system. So, the first big thing about cooking is, it gives us a huge increase, but we don't know yet how much. But a big increase in how much energy we get out of our food. 

When I was studying chimpanzees, I would normally take sandwiches with me, but there were days that, for one reason or another, I didn't, and because I was studying the feeding behavior of chimpanzees, I would regularly eat what they eat. If I eat everything that they eat that I could find. And on the days when I didn't have any prepared food with me, I would try to rely on what they eat. And you can eat it in the sense that you can chew it up and try to swallow it. Some of it is very strong tasting, which is kind of code word for really unpleasant, and some of it is okay. But it was not possible to find anything that I could fill my stomach with. 

Well, the short story is that I realized after a bit that I simply could not get enough energy out of a chimpanzee diet, and then I started thinking, well what would be the best place that you would get a raw diet in the wild? And there may be better places that the chimpanzee forest, I don't think there are many. And this sent me off looking for the difference between humans and other animals in terms of their ability to survive on raw food. And I very rapidly discovered that although there are some myths to go in the opposite direction, humans are different from other species because we have adapted biologically such that we cannot survive on raw food in the same way that other animals can. 

In some ways I shouldn't say we cannot survive, but we can't survive in the same way other animals can in this sense that whatever environment we are in, raw food is an unsatisfactory source. And the most dramatic example of this is that in the best study of the people who choose to live on raw food in modern urban environments, which is a great way to lose weight and can be very healthy and takes a lot of will, but is nevertheless has got many admirable aspects, but in the best study of people who do that, then first of all, a high proportion of people suffer energy shortage. They just are not getting enough energy to be able to maintain their bodies well. And the most dramatic point is that half of the women who eat all of their food raw are amenorrheic. That means that their ovarian system is closed down completely. Now, this is despite the fact that they are under ideal conditions. They are eating the best possible kind of foods being domesticated. There are no seasonal food shortages because they're eating from the global food resource; when it's not available in Germany, you can get it from Israel. They're eating food that is processed by blending and grinding and many raw foodists are even drying up to 114 degrees Fahrenheit and they're taking relatively little exercise compared to if you're gathering in the hot sun. 

So, despite all of these advantages, still 50 percent of women living on an ideal raw food diet, aren't able to make a baby. In fact, it's more than 50 percent, because those are the 50 percent that are completely amenorrheic, whereas, the chimpanzee on that diet would be pumping out babies. So, humans, there is clearly something different than others. And we actually know what it is. Compared to other primates, we have tiny intestinal volumes, compared to other primates, we have these very small guts, and we have very small teeth. So, these are signals of an adaptation that occurred in our evolutionary past to loosing the ability to eat raw food. Why should we do that? Well, because we were eating cooked food and the cooked food was great for us, we didn't need raw food anymore, so get rid of the ability to do it. And that's what we did. 

So we've been committed to eating cooked food for a period of time that is still under dispute, but I think it's 1.9 million years ago, all the way to the beginning of our genus. 

Question: What happened to the size of the brain and the intestine as a result of eating cooked food? 

Richard Wrangham: Well, there's this fascinating set of possibilities that relate the size of the brain to what has happened to the reduction to the size of our guts. And the background for this is that, in order to understand how brains get big over evolutionary time, you have to think both about the advantages of being smart because that's why you have big brains, of course. And the costs of fueling the brain because though our brains only represent only, what is it, 2.5% of the weight of our body, they represent about 20% of our basil metabolic rate. So they are disproportionately hungry in terms of the amount of calories they consume. And that means to have a big brain; you have to supply calories to it at a high rate. So, how do we do that? Well, is it by having a high basil metabolic rate? Not at all. We have exactly the basil metabolic rate expected of any other primate. Is it by taking some of the energy we use to feed some other organ and supply it to the brain? Yes. It has to be. So which organ is it? 

Well in the primates, the only way that they can find energy to give to their brains, as it were, is -- I shouldn't say the only way, but a major way, is through reduction of the size of the gut. Those primates that happen to have small guts because they happen to be evolved to eat a high quality diet are able to have some spare energy that they would have used for the gut, they no longer have, and they divert that to the brain. 

In other words, primates with small guts have big brains. Well, we have the smallest guts of all; we have the biggest brains of all. So, it looks as though there is a connection there and since the reason to for our small guts is the fact that we cook, that suggests that it's cooking that really facilitated this. And by the way, the time when our brain really takes off in size was about two million years ago. 

The reason it looks as though we started cooking about two million years ago is that it's around that time, 1.9 that you first see evidence of our ancestors having two signals that are associated with a small gut. And that is a narrower rib cage, and a narrower pelvis. In addition, you have, for the first time -- or no, not for the first time, but at that point, you have the biggest drop in the history of human evolution in the size of the teeth, the chewing teeth. Well that's associated with another effect of cooking, which is it makes your food softer. And because it makes your food softer, you don't need big teeth. Small teeth seems to be an advantage because maybe because they are less easily damaged than big teeth. So that happens then. 

And there's a third thing that happens around the same time which is this is the point in our evolution when we stopped being ape-like in the sense that we abandoned the morphology of the shoulder and the upper arms that allowed us to climb. Now for the first time, we look like us. And that means we are not very good at climbing in trees. Well, that means that we slept on the ground, and how are you going to sleep on the ground? In the middle of Africa with elephants and rhinoceroses and lions and leopards around? The only way that you would be willing to sleep like that nowadays is with a fire, if you are out in the open. And so that suggests that that was a time when our ancestors first controlled fire, enabled them to sleep on the ground, lose their climbing adaptations. Soften the food; get the teeth smaller. The food became much more digestible and they could have a smaller gut. 

So, those are all the things pointing to cooking emerging immensely older than people used to think. And people used to think, maybe 200,000 years ago. But I would say ten times as far as that. 

Question: Will there be evolutionary differences in the way raw foodists change in the next 50 years? 

Richard Wrangham: Well, no one is personally going to evolve in 50 years. So, raw foodists are romantics very often, or sometimes they're just practical people who discovered a way to make themselves feel better. A common reason for eating raw food is that people find that they have reduced symptoms of allergic reaction. And it looks as though some people are simply allergic to some of the consequences of cooking. 

So, if you discover that and you eat raw, you'll feel a lot better. Some people do it for philosophical reasons that we are animals; animals eat their food raw, so we ought to eat our food raw. And I say, I think this is wrong because we are the animals that have evolved to eat our food cooked. 

I'm full of admiration for raw foodists because it's an incredibly difficult thing to do particularly when people start. They describe how much of a struggle it is not to go out and get a candy bar, some bread, some pizza, or whatever it is. And it's a very awkward way to eat because it takes quite a long time to prepare your food. You have to eat a lot because you're basically hungry all the time. And so it interferes with your social life. Raw foodists tend to hang out with raw foodists. It changes a lot about your life. But, for those people who find it works for them, it clearly works really, really well. And there are a lot of us who would like to emulate this because it's a great way to lose weight. It's the ultimate way to control you're own body. 

Question: How does cooking bring humans together? 

Richard Wrangham: Yeah, the way to a man's heart is through is stomach, and all that sort of thing. I don't know. It's a sort of funny thing because people have long noted that cooking is very sociable. We like to eat with each other around the fire, we like to bring the food out of the oven together and eat as a meal. And yet there is no simple logical reason. There's no sort of technical reason why that should be. 

It's perfectly possible for an individual to cook for themselves, alone, for years as the model for Robinson Crusoe did, Alexander Selca in living alone on a tropical island for years. And we could all be doing that in theory. Why we do it nowadays, well I'm sure there's lots of cultural history to that. But I'm kind of interested in the question of why it starts. Why the pattern of people congregating in the evening to share the evening meal. Why does that happen in hunter/gathers and small-scale open-air societies? 

And there, I think, one can make a reasonable answer that it derives ultimately from something a little bit competitive and that is that anybody that cooks is giving a clear signal to everyone else that there is going to be food ready fairly soon. And they end up being vulnerable to the hungry and the lazy and the scroungers, who for one reason or another, don't have any food of their own and want to take some. And the short story, I think is that the tendency for us all to congregate and eat meals together represents the outcome of a system of social regulation, which is ultimately designed to protect those who are producing the food. And I think the way it works, ultimately, is that the women end up producing the food, there are men who could take it, and what happens is that women marry and the husband is functionally, among his other very important functions, he is there to protect her food from some lousy bachelor who comes home, is incredibly hungry and can't resist taking some food of the fire as soon as the cook's back is turned. And you see this written up and described in small-scale societies. The bachelors are thin and they're hungry and nobody's there to cook for them. And they have a problem. And the married men are superior to them and kind of keep them down. 

So that's one of the dynamics, but it means that it's great for husband's and wives to eat together, and of course the children are there, and then it can extend easily to others in the camp and suddenly you've got a rosy feeling and now you can afford, maybe in a sort of regulated way to give food out to those who don't have it. 

Question: What do you see as the new relationship between food and sex, or food and marriage? 

Richard Wrangham: I don't know how the new relationships are going or where they will go. I just think there's going to be many fewer constraints in the future. I think in the past, this has been a major constraint, the fact that you needed to have somebody in the household cooking for others and it was the women for I think reasons because men were able to get away with it. That is increasingly going to go away and isn't that great. We can get away from one particular source of sexist unfairness, and I think it heralds a much more exciting world in which women are able to participate in the professions and the life of the community to a far greater extent than before. 

Question: In 40 years, how will we evolve with cooking? 

Richard Wrangham: In modern society the future of food is, if it continues on its present path then we will be eating food that is increasingly highly processed because with every decade the great mills of the industrial food companies are grinding our foods into tinier and tinier particles. So, probably 40 years is too soon, or maybe it's a science fiction future anyway. But I could imagine that there will be a day when our foods will be piped into our houses in some form of algomash that we can then turn into the equivalent of today's hamburgers and donuts. The sort of the basic food that is cheap and very quickly processed. And I suppose exactly how it will happen is unclear, but what you can predict is that the food will become easier and easier to process, more and more processed outside the home, and therefore having fewer and fewer constraints on the domestic economy; on the organization of labor within the home. 

So, in a sense, that's a pessimistic view because it makes food sound uninteresting and maybe the world will be rich enough that it can afford the nice flavors and the interesting textures that the upper classes are able to play with nowadays, that would be nice. But it's also optimistic in the sense that the more that we can move to a world in which the traditional biological constraints on our social relationships are gone, then the more we all participate as equals, and particularly the more we erode the traditional placing of the woman in the home. 

Question: What keeps you up at night? 

Richard Wrangham: I think that I'm still very bothered by the fact that humans have not taken on board the degree to which we are a dangerous species. There's a very wide sense that -- the default conditions for humans is if no bad person comes along we'll al live in peace together. I'm kept up at night by the notion that that's a dangerous concept because it underestimates the propensity for things going wrong. And I'm hoping that, just as more and more people understand evolutionary theory and where we come from and be real about us in that way, more and more people will appreciate that we do have to take into account our aggressive propensities because when you do that, then you can design a safe world. Then you can recognize when danger is coming. So, just as people do recognize that men are dangerous as potential rapists and we take back the night and we don't allow people to have dark areas in cities where it's simply foolhardy for young women to walk alone. So life is safer if we recognize the dangers and anticipate them. And that way we've got a great future. 

Question: How do we recognize that? 

Richard Wrangham: Well in the same way that we are doing now. I mean, look what happened in Kenya in 2008. There was a contested election and something like 2,000 people died. And that could have turned into a Rwandan genocide. But actually there was huge intervention, and it was resented by the President of Kenya, but people slowly came in with a single voice and said, look, we recognize a tremendous danger here, we really care. They worked for an intense couple of months in particular, and what happens is, you end up with the President and the Prime Minster from the rival parties and they're working together. It doesn't mean that peace will always happen there, there may be further conflicts. But people are sensitive now to the dangers. And that's what I think is really important.