Who knew genes could get mean?
By Vicki Croke, 12/12/2000
Why do we humans so often fail miserably at losing weight, saving money, remaining sexually faithful, or quitting smoking?
Terry Burnham and Jay Phelan, two researchers armed with a wildly diverse array of data and a sly sense of humor, say we can blame it on the genes we've inherited from our hunter-gatherer forebears.
Our genes, the pair argue, encourage us to behave in ways that were helpful to our early ancestors but that today put us at risk of obesity, addiction, and divorce. In ''Mean Genes,'' Burnham, an economist at Harvard's Kennedy School of Government, and Phelan, a biology professor at the University of California, set out to explain why we do the things we do, and to help us short-circuit some of these impulses by understanding them better.
Globe reporter Vicki Croke talked with Burnham about wealth, happiness, and romance.
Q. You make the point that, in many ways, our genes are outdated for current society: We want to eat as much as we can in times of plenty, we have trouble saving money, we can be sexual cheats. How does understanding our genetic impulses help us curb our behavior? Can a fat person become thin after reading ''Mean Genes''?
BURNHAM. When giving advice on a topic like weight loss, it is impossible to come up with entirely novel suggestions. By more clearly seeing the problem, however, we predict which routes are likely to lead to success. While I can't summarize our whole chapter in a few words, one of the key conclusions is that people will not succeed in remaining hungry. In other words, calorie restriction is not the road to health and fitness, or even to losing weight.
Better to outsmart your passions than to attempt to overpower them with willpower alone. We provide the insights to help people outsmart their destructive passions. [For instance, since humans are genetically programmed to eat more than they should, the book suggests that people plan ahead and have a low-calorie snack available to avoid temptation by chocolate when the urge strikes.]
Q. What about comparing ourselves to other animals? (Burnham and Phelan compare human gender relations to those of the animals, noting that the gender that does the most nurturing of young tends to live the longest.)
It seems this is dicey business - picking and choosing certain behaviors from a huge repertoire in the animal kingdom. Can we really compare our romantic partners to aggressive elephant seals who are the size of, as you put it, fully-loaded Cadillacs? Or male bush crickets who lose a quarter of their body weight during sex?
BURNHAM. Throughout ''Mean Genes,'' we have selected stories that are true and are representative of the vast scientific literature. For example, male moorhens provide the bulk of baby bird care. Female moorhens are bigger than males, females compete for males, and females are particularly picky when it comes to male body shapes. Females prefer small fat males ideal for sitting on eggs. If moorhens had prisons, we speculate that all the inmates would be female.
The lesson isn't that males should take care of the offspring; it's that if one sex has the higher minimum investment (i.e., gestation in mammals or egg-sitting in moorhens), then the sex that does the investment is sought after and the sex that does the seeking dies at an earlier age because of the pursuit itself.
Q. ''Mean Genes'' is a surprisingly fun read, filled with amazing data that could keep any reader talking through many cocktail parties: The Mayan practice of using a ''toad enema''; the fact that the total energy investment of one pregnancy for one woman equals about 300 McDonald's hamburgers; a tablespoon of semen is enough to impregnate every woman in North AmericBurnham. What's your favorite ''Mean Genes'' factoid?
BURNHAM. I love the attempts animals make to keep their mates from cheating. Most people know that female black widow spiders eat their mates. Less well known is that male black widow spiders break their sex organs off in females, forming a primitive but effective chastity belt.
In some species, a male will sit upon a female for days after sex seeking to prevent her from having sex with his rivals. In other species, males seeking paternity carry females on their backs for prolonged periods. In one species of worms, males use ''cement glands'' to seal their rivals' sperm tubes shut.
Q. You are an economist, and you say that understanding genetic impulses helps inform your field. Are you saying all disciplines could benefit from a healthy dose of ''Mean Genes'' 101?
BURNHAM. Absolutely. Anyone interested in behavior of organisms that arose by natural selection should understand genetic evolution and science. Psychology is the furthest along in this process, called ''Consilience'' by E.O. Wilson. Economics, sociology, philosophy, and political science are still working with models of human nature that don't incorporate Darwin's insights.
And I've devoted my life to improving economics, also known as ''the dismal science.'' One of my research projects looked at why negotiations so often fail. The answer, in my study, is that high-testosterone men are willing to walk away from deals that low-testosterone men accept. Negotiation breakdowns of the sort that I studied are not supposed to occur (according to standard economics). The role of testosterone in this area removes the paradox. More generally, the rebuilding of economics on a better model of human nature will produce more accurate and useful results.
Q. Could this help us understand the political battle between Gore and Bush?
BURNHAM. There's no data, as far as I know, on testosterone levels in politicians.
Q. You take a potshot at the loyalty of dogs. Do you believe there is no such thing as altruism in dogs or, for that matter, in people?
BURNHAM. Both humans and dogs sometimes help others without any expectation of repayment. So, at one level, both we and they are altruistic. These behaviors evolved, however, for different reasons.
Dogs are domesticated versions of wolves and they have accompanied humans for at least the last 10,000 years. Those dogs that were nice to ancestral humans lived long enough to have puppies. Those that didn't pay attention to their owners, didn't have puppies, or at least not as many. Over many generations, human selective breeding has produced dogs that are keenly sensitive to their owners.
So dogs are built to care about people because caring paid off for ancestral dogs in the only currency that genes care about - offspring. Similarly, we know that humans evolved as the great cooperators. By working in groups, ancestral humans were able to eat, and avoid being eaten. Accordingly, we - the descendants of those who survived - are built with instincts that mediate cooperation.
As a consequence, humans are altruistic in certain settings. Not random acts of altruism, but specifically the sorts of behaviors that redounded to the benefit of ancestral humans.
Q. The book isn't really a self-help guide. And it's too funny to be a dry text on evolution and human impulse. What is it?
BURNHAM. Short, sassy and bold was our goal in the writing of ''Mean Genes.'' We hope it will be the first of a new genre of books. It provides advice built on a bedrock of scientific knowledge without being boring. Furthermore, it allows people to generate their own solutions, built upon a better understanding of human nature.
Q. What do you think is ''Mean Genes'''s most elegant solution to an everyday human impulse problem?
BURNHAM. In order to save, people need to hide the money from themselves. In fact, ''hidden'' money is the only source of retirement funds for average Americans. That is, Social Security, pensions, and accumulated home equity. The median American head of a household who is nearing retirement has under $10,000 in liquid financial savings. In other words, no savings at all that can be spent.
While there's no simple cure for drugs or obesity, savings rates are easy to improve. At the national level, we've done this by forcibly setting aside a chunk of income. At the individual level, we can do this by setting up payroll deductions that go to accounts that can't be touched for years.