A quarter-century ago stephen Emlen set out to investigate tales of an African utopia. He had heard of villages in Kenya where as many as 300 individuals lived in apparent harmony, despite being packed together in clustered homes. Even when food grew scarce, everyone shared what was available. Males and females took turns caring for children. Couples were monogamous, and to all appearances faithful. Grown children, rather than leaving home and starting families of their own, often stayed on to help their parents tend to younger brothers and sisters. Sometimes they helped neighbors. Altruism, in short, prevailed over self-interest.
The residents of this peaceable kingdom were not people--they were birds, of a species called the white-fronted bee-eater. But to Emlen, a Cornell biologist who studies animal behavior, that trivial fact did nothing to lessen the mystery of the phenomenon. Evolution should create struggle between bee-eaters as individuals try to maximize their own and their offspring’s chances of survival--not a purely selfless society. When Emlen set out for Kenya, he thought he was about to discover an exception to nature’s laws. But after years of research, he realized that he had instead found the exception that proves the rule: bee-eaters in fact do not altruistically help strangers; rather, through the complex dynamics of their large, multigenerational families, they help themselves. The myriad ways in which bee-eater parents, children, aunts, uncles, and grandparents behave toward one another exquisitely match what you’d predict from the principles of natural selection. Hidden under the utopian veneer is a swirling soap opera of love, deceit, harassment, divorce, and adultery.
Was Emlen disappointed with his hard-won findings? Not in the least. They led him to thinking about families. Why, he began to ask himself, do some species form families while others cut their ties to their children as fast as possible? Why do individuals behave differently in different kinds of family structures, and is that behavior predictable? In pursuit of answers to such questions, Emlen has embarked on a quest for a full-blown, mathematically rigorous model of the family.
It’s time to lay this out as a unified theory, he says--a theory of not just bee-eater families, but all families, humans included.
As Emlen walks into his office at Cornell he brushes past Clint Eastwood. The cardboard cutout of the movie star squints back in utter disgust, as if itching to gun him down. Ten feet away, Indiana Jones lurks in a doorway. Students set up the cutouts--they regard Emlen as something of a scientific swashbuckler, but he tries to play down the reputation. It is true that he has walked barefoot at night through Kenyan grasslands (so as not to disturb sleeping chicks), despite the deadly resident puff adders. And when in Panama, he has worried a bit about the alligatorlike caimans--especially when he gets excited, stands up in a canoe, spills a laptop or a pair of binoculars, and then has to dive into the water to wrench those valuables from the ooze. But no caiman has ever really bothered him; they’re interested only in birds and eggs.
