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Cultures of Animals May Provide Insights Into Human Behavior

By SHARON BEGLEY
May 7, 2004

When dinner time rolls around, bottlenose dolphins live up to their reputation for cleverness. Typically, the mammals corral a school of fish, or even trap them against a sand bar. Then they charge through the mass of prey to devour whatever lies in their path.

But of all the bottlenose dolphins in all the seas, one group off western Australia is unique. Before a hunt, they spear sea sponges with their tapered noses, make sure the sponges are on nice and snug, and then root around in rocky crevasses where fish are hiding and scare them out for easy snaring. Thanks to the sponges, their noses survive unscathed. The custom of proboscis padding has persisted for generations.

Scientists used to dismiss such behavior as merely a clever animal trick. No more. They now see such unique-to-a-group customs as nothing less than culture.

Although the term evokes operas and museums, scientists define "culture" more simply. It is behavior invented by one or a few animals in a group and taught to contemporaries and descendants, but not practiced by other populations of the same species. (If every member of a species flies to Mexico for the winter, for instance, the behavior is probably instinctive and doesn't count as culture.) After long insisting that humans are unique on this score, scientists are finding that other animals are members of the culture club, too.

"Nonhuman culture is currently one of the hottest areas in the study of animal behavior," primatologist Frans de Waal of Emory University, Atlanta, writes in the journal PLoS Biology.

In an echo of the bottlenose dolphins' use of sponges, one group of humpback whales in the Gulf of Maine has for generations engaged in a water-smacking custom, pounding the waves with their huge tails to confuse prey.

Not surprisingly, among the most cultured animals are chimpanzees. When scientists pooled observations from seven sites in Africa, they found that different troops have distinct cultural traditions.

The chimps of Ivory Coast's Tai Forest -- and no others -- mash parasites against their forearms and remove bone marrow from monkeys they've hunted. Only the chimps at Tai and Boussou, Guinea, meticulously choose flat stones on which to crack rock-hard nuts with hunks of wood. Only those of Mahale and Gombe, Tanzania, and Kibale in Uganda perform rain dances, dragging branches along the ground during a downpour and slapping the ground with them. Only at Boussou do chimps spread leaves to sit on when the ground is wet. And only in a forest in Sierra Leone do they cover the thorns of the kapok tree with smooth sticks so they can scramble around the treetops, gathering fruit, without getting pricked.

Each cultural tradition has endured for generations, suggesting that adults teach it to offspring.

The most recent evidence of culture among animals comes from studies of olive baboons. It stands out because the learned behavior is so at odds with how badly baboons customarily behave.

Baboons tend to be fierce and aggressive, and the "Forest Troop" in Kenya's Masai Mara Reserve fits the mold. Males fought over everything (grub, girls ...) and nothing. But in 1982, the aggressive males began raiding the garbage pit of a nearby tourist lodge, gorging on rotten meat. Almost half of the troop's males -- and all the aggressive ones -- died of tuberculosis, leaving, as Stanford University biologist Robert Sapolsky puts it, "a cohort of atypically unaggressive survivors."

When he and his colleague and wife, Lisa Share, returned to the troop in 1993, they found a peaceable kingdom. The males better tolerated their social inferiors and groomed females more than those in the 1980s had. They were also less likely to harass females or terrorize subordinates. There were fewer aggressive encounters between troop members, and less angst, as measured by stress-hormone levels, among low-ranking males.

The reason had nothing to do with the non-aggressive males who survived the TB epidemic. They had all died off. And because males leave their natal troop and join a new one at adolescence, the 1990s males didn't even include any offspring of the peaceful dads. Although young males joining the troop at first threatened and lunged at their new neighbors, they picked up the local customs quickly.

"To anyone who believes that behavior is hard-wired by evolution," says Prof. Sapolsky, "this finding is problematic. It seems like there is not one best or most adaptive way to behave."

At a time when aggression seems so much a core ingredient of human nature, says biologist Hal Whitehead of Dalhousie University, Halifax, Canada, "by looking at culture in nonhuman animals, we may be able to learn a fair bit about genes and behavior."

It is all the fashion to assert that genes have behavior on a short leash, but even something as seemingly innate as aggression in baboons can change if conditions are right. Aggression, and probably other behaviors believed to be innate, may well arise from and be subject to powerful cultural influences. "Even the fiercest primates do not forever need to stay this way," notes Prof. de Waal. Does that include humans?

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