Baboons Live Longer If Their Moms Are Social

Six days a week for 17 years, primatologists observed more than 65 female baboons in the Moremi Game Reserve, a national park in Botswana. They tracked things like the baboons’ social interactions, their ranking within the group, and the survival rates of their offspring. Now, a team of researchers has looked at the data and found that the best way to predict whether a baboon would live to adulthood is to look at the strength of its mother’s relationship with other females.
The offspring of females who formed strong social bonds with other females–especially their mothers and adult daughters—lived significantly longer than the offspring of mothers who formed weaker bonds with these relatives. (The strongest social bonds were shown to be between mothers and adult daughters, then sisters.)
Dorothy Cheney, a biologist at the University of Pennsylvania who worked on the study, explains why surviving into adulthood (about age 5 for baboons) is so important:

Females who raise offspring to a reproductive age are more likely see their genes pass along, so these findings demonstrate an evolutionary advantage to strong relationships with other females. In evolutionary terms, social moms are the fittest moms—at least when it comes to baboons.

These findings, the authors write, “parallel those from human studies, which show that greater social integration is generally associated with reduced mortality and better physical and mental health, particularly for women.”


Do Baby Apes Giggle Like Human Infants Do?

Apparently so, according to a new study that analyzed the “tickle-induced vocalizations” of human infants and young apes.
According to the researchers, infant and juvenile orangutans, chimpanzees, gorillas, and bonobos “laugh” when they’re tickled, even though it sounds acoustically different from human laughter. (We do laugh most like chimps and bonobos, however, which are genetically closest to us). The study shows “the evolutionary continuity of a human emotional expression,” says Marina Davila Ross, a psychologist at the University of Portsmouth who worked on the research.
“The results suggest that the evolutionary origins of human laughter can be traced back at least 10 to 16 million years to the last common ancestor of humans and modern great apes,” the researchers write in the journal Current Biology.
There is “clear evidence of a common evolutionary origin for tickling-induced laughter in humans and tickling-induced vocalizations in great apes,” they report. “At a minimum, one can conclude that it is appropriate to consider ‘laughter’ to be a cross-species phenomenon.” —Heather Wax


Empathy Appears to Have Genetic Component

A new study on mice suggests that the ability to empathize with others—to sense and act on their emotional states—has a genetic basis. Researchers from the University of Wisconsin-Madison and Oregon Health and Science University had a bunch of highly social mice watch while they put another mouse in a cage. The mice then heard a 30-second tone at the same time the mouse in the cage (now out of view) was given a mild foot shock, causing it to squeak in distress.
When the gregarious mice were later put in the cage and the tone was played, they showed clear physiological signs of aversion (like freezing in place), even though they were never shocked. These mice had learned to associate the tone and the cage with something negative; the squeaking mouse taught them that the tone predicted distress. When the researchers tried the experiment again, this time with mice from a genetically different strain that is less social, they found that the mice didn’t show any response to the tone once inside the cage. In other words, they didn’t respond to the other mouse’s distress.
“The core of empathy is being able to have an emotional experience and share that experience with another,” says University of Wisconsin-Madison graduate student Jules Panksepp, who worked on the study. “Deficits in empathy are frequently discussed in the context of psychiatric disorders like autism. We think that by coming up with a simplified model of it in a mouse, we’re probably getting closer to modeling symptoms of human disorders.”


Photographic Evidence

Researchers at the Wildlife Conservation Society and Max Planck Institute for Evolutionary Anthropology have released the first ever photos of wild gorillas mating face to face, looking into each other’s eyes. “Understanding the behavior of our cousins the great apes sheds light on the evolution of behavioral traits in our own species and our ancestors,” Thomas Breuer, the German conservation biologist who took the pictures in the Republic of Congo, said in a press release. —Heather Wax

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