Born to Be Good: The Science of a Meaningful Life

This kind of sibling conflict, Frank Sulloway reveals in Born to Rebel, is expected, based on evolutionary theory. Siblings share, on average, 50 percent of their genes, and compete over numerous resources, from the protection and affection of parents to food to mates—particularly when resources are scarce. Sibling conflict is frequent, widespread, and, on occasion, deadly. Sibling sand sharks devour one another prior to birth in the oviducts of the mother, until one well-fed shark emerges. Once a blue-footed boobie drops below 80 percent of its body weight, its siblings exclude it from the nest, and at times will peck it to death. Infant hyenas are born with large canine teeth, which they often turn to deadly effect upon their newly born siblings.

Conflict is synonymous with human social life. Yet early hominid conflict differed from that of many other species: It was met with evolved capacities to reconcile. This essential insight can be traced back to the observations of Jane Goodall and Frans de Waal, who documented how our primate relatives reconcile after aggressive encounters. Prior to Goodall and de Waal’s work, the prevailing wisdom, developed by ethologist Konrad Lorenz, was that following an aggressive encounter, aggressors moved away from each other as far as possible. This view might make sense for solitary species, like the golden hamster, who flee upon attack, or territorial species, like many birds, who rely on birdsong to create invisible but audible property lines to avoid deadly conflicts.

For many mammals, though, these options—fleeing the group or solitary territorial arrangements—do not make evolutionary sense. Our hominid predecessors were dependent upon one another to defend against predators, hunt, reproduce, and ensure that offspring reached the age of viability and reproduction. Individuals who were better able to negotiate conflicts almost certainly fared better in the tasks of survival and gene replication. Recent studies have found that wolves who have been kicked out of their group for excessive aggression and an inability to play are less likely to reproduce and more likely to die. Many physiological difficulties associated with human isolation—namely, increased stress, weaker responses to disease, and even shorter lives—suggest that our survival depends on healthy, stable bonds with others. Conflict is costly and painful but better than the alternative—a solitary existence of fending for oneself. Out of the perpetual conflict that runs through human social life emerged a rich array of capacities that short-circuit or defuse conflict—appeasement displays, forgiveness, play, teasing, and laughter.

FRAGILE MONOGAMY AND THE NEW DAD

 

Finally, our Cro-Magnon anthropologist would have to devote a surprisingly chaste chapter to the bawdy politics of our primate predecessors. Their sexual organization differs from that of our closest primate relatives, and makes us resemble the local Towhee or warbler flitting about rather than baboons or chimpanzees. We are relative prudes compared to these primate relatives. Once a female chimpanzee is sexually mature at age fifteen, she advertises her sexual receptiveness by a large pink patch of sexual skin, and for a ten-day period during a thirty-six-day menstrual cycle, she copulates several dozen times a day, with all or most of the adult males in her social group. Aggression and jockeying for access to female chimpanzees during these periods become all-consuming for male chimpanzees. Females raise offspring largely on their own; males contribute to the community but not to individual offspring, and males don’t know which offspring they have fathered.

Then there are the bonobos, now recognized as a separate species from chimpanzees, and widely envied by humans yearning for the next sexual revolution. Bonobo females are sexually active for about five years before they become fertile, and copulate freely with many of the adult males in their immediate social group. Female and male homosexual relations are common. Younger males often engage in sexual activity with older females in what looks like sexual initiation play. Sexual contact among the bonobos is the basis of friendships, conflict reduction, and play.

The monogamous tendencies documented by our Cro-Magnon anthropologist, by contrast, are unusual for higher primates. They have never been observed, except in hominids, in species where the sexes mix in large groups without territorial boundaries. This sexual organization had several important implications. Females evolved to become sexually active throughout their menstrual cycles. Males and females could maintain exclusive sexual interest in each other. For example, in a survey of world cultures, monogamy was recognized as official policy in only 16 percent of 853 societies sampled, but sexual monogamy was the most common sexual pattern. Males evolved to know who their offspring were and to provide resources and care to them.