Mean Genes

An interview with


DNA Discipline

Terry Burnham and Jay Phelan on Taming Your Primal Instincts

Everybody's got a vice. Fatty foods, slot machines, alcohol, infidelity--these are the personal demons that cause us to wreck our lives, feel guilty all the time, and even endanger our health. And it looks as if most of our worst behaviors have very sensible biological instincts behind them. But don't despair, say Harvard economist Terry Burnham and UCLA biologist Jay Phelan; you can take control of your biological instincts with a little understanding and some simple actions. In our interview, Burnham and Phelan talk about their book Mean Genes and how we can learn to live with our DNA demons. In the introduction of Mean Genes, you mention the "modern Darwinian revolution." What do you mean by that?

Terry Burnham: Darwin published The Origin of Species in 1859, and he was really puzzled by a set of behaviors, including altruism. Then, in the second half of this century, there were a couple of big papers published on these issues. They solved this puzzle, but then they opened up this whole field of study--how evolution relates to behavior. All sorts of behaviors that had not been understood now got looked at correctly, through the lens of natural selection.

Jay Phelan: In The Origin of Species, Darwin had wondered why, for instance, in species like honey bees, individuals would die protecting the hive. He couldn't understand why they would do that--it didn't fit with his theory at all. And he actually said, if we can't figure out why this is, then the whole theory is sunk. So he put it out there, and it was a hundred years before someone figured out how that actually could be true and still be consistent with this theory. Did you consciously build on the work of E.O. Wilson and other sociobiologists to extrapolate your practical tips?

Burnham: Absolutely. We are huge fans of that body of literature, so one of our jobs was to translate the science that was out there. But there are also ideas in Mean Genes that are new, like the "Risk," "Happiness," and "Friendship" chapters. I don't think those ideas are out there, at least not very clearly written anywhere. Sociobiology, with its notion that both good and bad behaviors are regulated by biology, often touches on some very personal things for people. The idea that biology is destiny is particularly troublesome. Did you consciously avoid dealing with controversial human behaviors?

Phelan: You're right, so much of the book comes from the ideas of E.O. Wilson and sociobiology, which is often the "straw man" of genetic determinism. But the subtitle of Mean Genes is Taming Our Primal Instincts. So the central idea of the book is that we don't have to be the way our instincts demand.

I don't think we wanted to write a book that said, guess what? Here's a lot of depressing stuff: genes are telling you to do this or that or the other thing. We don't believe that. We believe that you feel nudges and you're more likely to go one way or another, but there's a lot more flexibility than people sometimes acknowledge.

Burnham: Anybody who studies animal behavior realizes that behavior is contingent on what's going on in the environment, as well as within the animal. When a plant grows toward the sun, it's responding to its environment. As we talk about a little bit in the last chapter, "Surviving Desire," humans have an unprecedented ability compared with other animals to control their instincts. Anybody who is really serious about understanding behavior would be wrong to use the genetic determinism argument. You show in your book that our genes are giving us signals based on our ancestral environment. They're living in the past, so to speak. How long do you think it will take our genes to catch up with us, if ever? And if they do, how do you suppose that will change our behaviors?

Phelan: That's a very good question, because obviously, if our genes became adapted to this world where we were hunter-gatherers, at some point we would assume they'd get adapted to our industrial world.

It's difficult to answer, though, because (A) we're living in so many different environments today, around the world. Everyone isn't living in an industrial world. And (B) evolution moves really, really slowly. Even if you're doing laboratory work where you're trying to create a fruit-fly. I've done these experiments a lot where I try to create fruit-flies that are better at resisting starvation, or dehydration, or something, and it takes dozens of generations before you see any kind of change at all.

When you transfer that out to humans, a 5 percent change in 30 or 40 generations would be the fastest change that would ever be possible. And even then, it would take thousands and thousands of years to be complete. A lot of our behaviors are motivated by the desire to successfully reproduce. How do those people who choose not to have children fit into the genetic picture?

Burnham: Clearly, we're not robots carrying out programming, and we can do all sorts of things that don't have the same effects as they would have to our ancestors.

It's tough to try to get across the difference between the creation of an emotional structure and its effect on reproduction. So, you know, just take the most basic of sexually related feelings: sex feels good for most people. In ancestral times, pursuit of that feeling led to babies, because there was no birth control until very recently. If genes build bodies where people feel good when they have sex, and then people have sex, then without the person trying to have babies, they end up having babies.

But in modern times, you have this mismatch which can cause problems, but it also gives us extra tools. Technology is a two-edged sword. It's one of the big reasons why we have problems, but it's also one of the sources of solutions. So, by using the cerebral cortex side of our brain to create birth control, we can control the outcome of sex more readily. How does sex get tied up with risky behaviors? For instance, why do people who don't want to have kids have sex without birth control (barring any religious reasons)?

Phelan: We like risk, because in our ancestral environment, it often led to good outcomes. We have brains that are built to feel good when we engage in some aspects of risk. So you're walking around and you think, ooh, I want to do something risky, whether it's sex without birth control, or riding a motorcycle, or loving roller coasters, or just liking really spicy food, all you know is that somehow that makes you feel good.

Burnham: You know the phrase "salt to taste"--you add certain chemicals to your food and it tastes better. And the function of spice, as well as the reason it tastes good to us, is that it kills bacteria.

So we have this taste that evolved for a very specific reason, but we even put it in food that we know doesn't have any bacteria, because we still like the taste of the spice. In the same way, risk spills over across all sorts of domains where it had an original function that was positive--now we add risk to taste. Even in domains where it would never have made any sense, it just feels good to have a little bit of it in there. Is that why someone who's deathly afraid of snakes might go see a horror movie about snakes?

Burnham: Yes. I think it's partly that your fear jingles up the dopamine receptors and that feels good. But also, if you put chimpanzees around snakes, they're scared, but they also observe them. There's a natural taste to learn things that are important. It's important not just to learn to avoid snakes, which the fear response does, but to be fascinated by them, so you can watch where they go and observe their behavior, and learn more about them.

Phelan: Yes, it's crucial that you are keying into things that are potentially dangerous to you rather than just ignoring them. I do love that thought, though--people going to scary movies or riding roller coasters, and all they're doing is causing their brain to think that it's in a situation that ancestrally had some value. You mention in the book that we're not a species that's good at figuring odds. For instance, we're afraid of dying of things that aren't really dangerous to us any more. Why is that?

Burnham: We're really bad at estimating sources of death. When you line up things that scare people with modern sources of death, like car crashes and airplane crashes, it's really bad; but then if you line them up with hunter-gatherer causes of death, pregnancy is the favorite one.

If you ask women what they're scared of, many are very terrified of giving birth. But they're also really interested in it. What's it like? Is it dangerous for the mother? And so forth. But when you look at the statistics in the United States, almost no women die giving birth. It seems very odd. But if you look at modern-day Africa, where one in 16 women in their life will die of pregnancy, or modern hunter-gatherers, where about one out of 10 women die giving birth, it all makes sense. Terry, you spent some time trading stocks--how does evolution play a role in the life of the day-trader?

Burnham: I don't think it plays much role in the day-to-day basis. Again, we know the reason why humans take risks, and some humans like risk more than others. I happen to be one of those people. And it really pays for day-trading firms to help me with my risk. It's less evil, I suppose, than a drug dealer and probably along the lines of a McDonald's. Their goal is to make money, and they make money by selling a product that I like. There's nothing wrong with that, but it ends up making me very unhappy. Is it similar to casinos and lotteries? Even people who understand the math still play games of chance.

Phelan: It's funny that you mention that, because I can't muster any interest at all in day-trading. But I go to Las Vegas once or twice a year and my God! I get the rush of a crack addict when I throw a $100 bill down on the roulette wheel just on red or something! And I know that, on average, I'm just giving away more than half of my money, and yet it just feels so good, the excitement of it all. The fact that there's an entire mecca in the desert devoted to that particular genetic predisposition is pretty astonishing.

Phelan: It's funny also to think about the fast-food restaurant that's on every corner in every big city. They're choosing to exploit another weakness--our desire for fatty foods--that used to be a good thing in the way we were built.

Burnham: We could go on and on: Sports teams, which are proxies for warfare. Soap operas as substitutes for social information. Prostitution and other commercial sex trades as proxies for becoming parents. Life is filled with these things. The practical tips you offer in the book are really fascinating, but they seem to run counter to most self-help books that counsel very specific discipline. Don't eat protein, eat only protein, that kind of thing.

Phelan: We're saying that discipline is not one generic term. There are actually different kinds of discipline. If I'm at home and I have tons of food there, there's the discipline I exercise this minute not to eat some cereal, because I love cereal. Now there's the discipline not to eat the cookies. Now there's the discipline not to eat the leftovers from yesterday. And there's all this discipline, minute after minute after minute, and I know that I will fail. Eventually, I will eat.

Figure out when a little bit of discipline will go a long way, and flex your discipline muscle then, because that's when you're more likely to win.

Burnham: And it goes right along with our idea, too, that you have to know the nature of the enemy within. With food it's really straightforward. Ancestral humans were hungry, and we have instincts that say, when there's food lying around, put it in your stomach; don't let it rot or get stolen by somebody else. So you're really fighting against your human nature if you expect yourself to sit around with extra calories in the cupboard.

The idea that you're going to sit around for weeks with a tasty cookie in the cabinet is really tough. You're setting yourself up for failure. Some people can do it, but it's really hard.

Phelan: Yes, in the abstract, "eat less and move around more" does work. But when you put it in practice, it almost always fails.

Burnham: Part of the reason that it's such a hard problem is that the thing that works best in the short term is exactly the thing that doesn't work in the long term, specifically calorie restriction. In the book we say, if you have a high school reunion on Friday and you want to look your best, starve yourself between now and Friday. But know while you're doing it that you're going to make yourself larger in the long run. Your body will misinterpret the signal. Why would a human in an ancestral setting starve themselves? It must be because they have no food. Oh, my gosh! We're in a crisis! Shut down the system and prepare for starvation.

There are many variants on diet books, but many of them really come down to calorie restriction. It could be, eat only the purple food, or eat this on this day and that on the other. But if you really boil it down, what it comes down to is you're asking those people to calorie-restrict in the presence of food. And that works great in the short term, but it has no evidence that it works at all in the longer term. Some folks seem to have all the willpower they need around food, while others eat everything in sight. Is that just due to genetic variation?

Phelan: Yes, it's due to variation, and it's one of the thorniest problems in biology--why is there so much variation? Because that's exactly it; you can say you have no problem with eating all the cookies in your cupboard, but then look through our table of contents in Mean Genes. Go to risk-taking, or drugs, or infidelity. At some point you're going to push the buzzer and say, OK, I admit I have problems with that one. None of us have all of the problems in Mean Genes, but we all have some of them. One of your tips was to destroy half the chips in a bag before you eat a single one, to prevent yourself from eating the whole bag.

Burnham: The key is to remove them somewhere or another. The removal process has to be done before you begin eating.

One of my students just e-mailed us and told us he's lost about 80 pounds. He sent us a long e-mail with all the little tips he used, including exactly this--that before he starts eating, he decides how much he wants to eat and he destroys the part he doesn't want to eat. And it really is working for him. Destroying food? My grandmother would be rolling in her grave!

Burnham: But your grandmother is much more representative of a person who might have known what food shortages were like. For industrialized humans who are relatively rich, our problem is too much food. It's really bizarre! And we constantly have to run away from it.

Phelan: What you've got to do is just give half the bag of chips to your neighbor and say, I don't care what I say, do not give these to me until tomorrow. And then your neighbor can give you something she needs to stay away from.

Burnham: It's back to this big picture: you can try to fight human nature, or you can try to use human nature to get the goal that you want. Does the same formula apply to infidelity?

Phelan: Oh yes! I think of that as a classic one. Again, it's all the same approach--don't put yourself in the situation where you're going to be weak. Before it was food; now it's with someone that you're attracted to, or someone that even before you've met them, you can imagine that you'll be attracted to them. Kind of makes you step back and examine every little thing you do, doesn't it?

Burnham: (laughter) That's all we've been doing for about 10 years now.

Phelan: It's a new lens for viewing the world. Every single interaction I have every day is richer because I'm thinking about it this way, and I really believe that it helps me every day, dozens of times. The advice you gave about how to avoid eating the dessert on an airplane meal--to smear mayonnaise on the brownie--is really interesting. Would it work to just hide the brownie?

Burnham: Out of sight does help. Chimpanzees have a problem akin to what we have sometimes. If there's something good right in front of them, they can't help going for it. I'm the same way with certain things. If it's in front of me, I'll eat it. But just a thin veil that prevents you from seeing it is enough sometimes.

Phelan: I've been doing one lately to avoid eating too many fries. I absolutely despise onions, but now I'll have them bring onion with my fries, and I smear the onion on 80 percent of the fries. All my desire goes away because I hate onions so much, and the flavor is on the fries. Then I can eat the few French fries that haven't touched the onion, and I'm happy. It doesn't require any willpower.