Despite being separated by 95 million years of evolution and utterly different environments, female chimpanzees and dolphins have a whole lot in common. They’re the bedrock of family life, hardworking moms who feed and raise kids while their fathers are out roaming. “If we want to understand what is driving social systems where males do not provide care,” says Heidi Pearson, a behavioral ecologist at Stony Brook University, “we should be looking at females.”
In a study published June 22 in Evolutionary Anthropology Pearson compares the behavior of female chimpanzees and bottlenose dolphins in detail. Both species form complex societies, hunt cooperatively, solve sophisticated cognitive problems, live for decades and invest years in rearing their offspring. But whereas young males spend the bulk of their time with a couple close compatriots, defending territory and chasing mates, females spend a lot of time on their own.
By hunting or gathering away from the group, both chimpanzee and dolphin moms ensure that what they find goes to their young. Like humans, they socialize some with other moms and share kid-watching duties, but they don’t have time for much fraternizing. Despite striking similarities, the animal groups do differ in some ways. On the whole, female dolphins are more sociable than female chimps. Pearson suspects this is because it’s easier to swim than cross a forest, allowing dolphins to conveniently rejoin groups. Predators behave differently in the water too. While a chimpanzee can easily escape a leopard by climbing a tree, a dolphin has nowhere to swim from a shark. Traveling in a group is much safer than swimming alone.
The full effect of evolving in these different environments is a mystery that Pearson hopes to investigate in follow-up studies. “It’s one thing to say, ‘These animals are very complex socially,’” said Lori Marino, an evolutionary neurobiologist at Emory University. “But Pearson is actually taking that statement and diving into what it is about social complexity and the particular lives of chimpanzees and bottle nose dolphins that are comparable. Now we have more detail about how these animals have converged and why.”
Source: Wired Science