Close Social Ties Make Baboons Better Mothers, Study Finds

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ScienceDaily (June 11, 2009) — Baboons whose mothers have strong relationships with other females are much more likely to survive to adulthood than baboons reared by less social mothers, according to a new study by researchers at UCLA, the University of Pennsylvania and other institutions.

"If you're a baboon, the strength of your mother's relationship with other females is the best predictor of whether you'll live to have children yourself," said Joan Silk, the study's lead author and a UCLA professor of anthropology. "The study adds to mounting evidence of the biological benefits of close relationships among females."
The findings are significant because "survivorship to reproduction is the gold standard in evolutionary biology," said co-author Dorothy Cheney, a professor of biology at the University of Pennsylvania. "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."
The study appears online in the Proceedings of the Royal Society B, a peer-reviewed journal published by the national academy of science of the United Kingdom and the Commonwealth.
Silk, Cheney and seven other researchers from the University of Pennsylvania, the University of Michigan and the University of St. Andrews in Kenya analyzed 17 years worth of records on more than 66 adult female baboons in the Moremi Game Reserve, a 2,000-square-mile national park in Botswana that teems with wildlife.
Collected on the ground by primatologists who tracked the baboons six days a week, 12 months a year, the records reflected the sex and survival rates of baboon offspring, as well as telling details of the mothers' social lives, including their ranking within the group, as measured by the direction of approach/retreat interactions, and the amount of social interactions they had with each of the group's other females.
In addition to showing how often one animal approached another, the records of social interactions included details of grooming, which is known to be the primary form of social interaction in Old World monkeys. The researchers noted how much time — frequency and duration — the females spent grooming each other and how often they solicited grooming from other females.
Of all the factors studied, the strength of a mother's social bonds with another female had the most significant effect on the survival rates of offspring. A mother's dominance rank proved to have no affect on the survival rate of her offspring.
"We really expected dominance status to be more influential than it proved to be," Silk said.
Offspring from the most social mothers turned out to be about one-and-a-half times more likely to survive to adulthood than offspring from the least social mothers.
The strongest social bonds were measured between mothers and adult daughters, followed by sisters and all other potential relationships, including aunts, nieces, cousins and baboons with no familial ties. Bonds between mothers and adult daughters proved to be three times stronger than those between sisters and 10 times stronger than relationships with other females.
"What really matter to these girls are mother-daughter bonds," Silk said. "They're really strong, and they last forever. If your mom is alive, she's one of your top partners, always. But more importantly, it's the strength of these bonds, because females whose bonds with their mothers and daughters were strong had higher offspring survival than females whose bonds with these relatives were weak."
Silk's past research with Jeanne Altmann, the Eugene Higgins Professor of Ecology and Evolutionary Biology at Princeton University, and Susan C. Alberts, a professor of biology at Duke University, on baboons in the Amboseli Basin of Kenya had found a higher survival rate for baboons with social mothers, but the research only tracked offspring through the first year of life.
For the new study, researchers followed offspring from 1 year of age through sexual maturity — roughly 5 years of age. The new study also differs from past baboon research by focusing on the strength and duration of relationships between pairs of females rather than on the amount of social interactions in general.
"The benefit comes not from being wildly social — it's about having close social bonds," said Cheney, who runs the Moremi baboon-tracking project with University of Pennsylvania psychology professor Robert M. Seyfarth.
"These females form strong relationships with particular partners," Silk said. "They don't treat everyone the same. They spend a lot more time with — and a lot more time grooming — some females than others, and these relationships tend to be very long-lasting."
Additional research is needed to determine how the female bonds improve infant survival, but it may have to do with such stress hormones as cortisol, Silk said. Research has shown that prolonged elevations of stress hormones in primates can lead to cardiovascular disease and other serious health problems. Research has also shown that grooming tends to lower these stress hormones in baboons.
"Our research suggests that somehow there is a link between the kind of social relationships you form and the natural, normal stresses that occur in everyday life, and that seems to have — at least in baboons — a long-term effect on reproductive success," Silk said.
Said to share 92 percent of their DNA with humans, baboons are close relatives of humans. Baboons and humans last shared a common ancestor about 18 million years ago. The new findings on social interactions among mothers parallel recent research that has shown health benefits for humans who enjoy particularly close social networks.
"Our findings suggest benefits from forming close relationships are built into us from a long way back," Silk said.
The research received funding from the National Geographic Foundation, the Research Foundation of the University of Pennsylvania, the Institute for Research in Cognitive Science at the University of Pennsylvania, the National Institute of Health and the National Science Foundation.
Adapted from materials provided by University of California - Los Angeles.

Primates Expect Others To Act Rationally

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http://www.sciencedaily.com/releases/2007/09/070906140753.htm

Science Daily — When trying to understand someone's intentions, non-human primates expect others to act rationally by performing the most appropriate action allowed by the environment, according to a new study by researchers at Harvard University.

The work was led by Justin Wood, a graduate student in the Department of Psychology in the Faculty of Arts and Sciences at Harvard, with David Glynn, a research assistant, and Marc Hauser, professor of psychology at Harvard, along with Brenda Phillips of Boston University.
"A dominant view has been that non-human primates attend only to what actions 'look like' when trying to understand what others are thinking," says Wood. "In contrast, our research shows that non-human primates infer others' intentions in a much more sophisticated way. They expect other individuals to perform the most rational action that they can, given the environmental obstacles that they face."
The scientists studied the behavioral response of over 120 primates, including cotton-top tamarins, rhesus macaques and chimpanzees. These species represent each of the three major groups of primates: New World monkeys, Old World monkeys and apes. All three species were tested in the same way, and the results showed the same responses among the different types.
In the first experiment, the primates were presented with two potential food containers, and the experimenter either purposefully grasped one of the containers, or flopped their hand onto one of the containers in an accidental manner. For all three species, the primates sought the food container that was purposefully grasped a greater number of times than the container upon which the hand was flopped. This indicates that the primate inferred goal-oriented action on the part of the experimenter when he grasped the container, and was able to understand the difference between the goal-oriented and accidental behavior.
In the second experiment, the researchers asked if the primates infer others' goals under the expectation that other individuals will perform the most rational action allowed by the environmental obstacles. Again, the primates were presented with two potential food containers. In one scenario, an experimenter touched a container with his elbow when his hands were full, and in another scenario, touched a container with his elbow when his hands were empty.
The primates looked for the food in the container indicated with the elbow more often when the experimenter's hands were full. The primates considered, just as a human being would, that if someone's hands are full then it is rational for them to use their elbow to indicate the container with food, whereas if their hands are empty it is not rational for them to use their elbow, because they could have used their unoccupied hand.
Developmental psychologists have long understood that young children are able to engage in this type of rational action perception, but scientists have not understood if this ability is unique to human beings, or shared with other animals. This study suggests that this ability evolved as long as 40 million years ago, with non-human primates.
"This study represents one of the broadest comparative studies of primate cognition, and the significance of the findings is reinforced by the fact that these results were consistent across three different species of primates," says Wood. "The results have significant implications for understanding the evolution of the processes that allow us to make sense of other people's behavior."
The findings appear in the Sept. 7 issue of the journal of Science.
The research was funded by the National Institutes of Health, the Guggenheim, and the National Science Federation.
Note: This story has been adapted from a news release issued by Harvard University.

Fausto Intilla

www.oloscience.com

Higher Social Skills Are Distinctly Human, Toddler And Ape Study Reveals

Source:

http://www.sciencedaily.com/releases/2007/09/070906144113.htm

Science Daily — Apes bite and try to break a tube to retrieve the food inside while children follow the experimenter's example to get inside the tube to retrieve the prize, showing that even before preschool, toddlers are more sophisticated in their social learning skills than their closest primate relatives, according to a report published in the 7 September issue of the journal Science.

This innate proficiency allows them to excel in both physical and social skills as they begin school and progress through life.
"We compared three species to determine which abilities and skills are distinctly human," explained Esther Herrmann of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany and lead author of the research paper. Humans differ from their great ape relatives because human brains are about three times the size of the closest primate relatives and humans have language, symbolic math and scientific reasoning.
"Social cognition skills are critical for learning," Herrmann said. The children were much better than the apes in understanding nonverbal communications, imitating another's solution to a problem and understanding the intentions of others," she said.
This is the first comprehensive test comparing social and physical skills of children, chimpanzees and orangutans, Herrmann explained, adding that the findings provide important insight into the evolution of human cognition.
The findings support the cultural intelligence hypothesis that suggests that humans have distinctive social cognitive skills to interact in cultural groups, Herrmann said. An alternate hypothesis suggests that humans differ from apes uniformly across physical and social cognitive tasks because they have more general intelligence.
About 230 subjects -- chimps, orangutans and 2.5 year-old children -- were compared using a battery of tests and found all to be about equal in the physical cognitive skills of space, quantities and causality. In the social skills of communication, social learning and theory-of-mind skills, the children were correct in about 74 percent of the trials, while the two ape species were correct only about 33 percent of the time.
The researchers chose to study children at an age when they have about the same physical skill level of chimpanzees. Children at 2.5 years are old enough to handle these tasks and people have not taught them too much so they provide a good comparison, Herrmann said. The apes ranged in age from 3 to 21.
All of the subjects -- about 100 chimps (Pan troglodytes), 100 children (Homo sapiens) and 30 of the more evolutionarily distant orangutans (Pongo pygmaeus) -- were given the same cognitive tests that the Max Planck group developed and named the Primate Cognition Test Battery. The battery analyzes primate cognition dealing with the physical and social world (involved in foraging, for example) and was developed based on the primate cognition research of coauthors Josep Call of the Max Planck Institute for Evolutionary Anthropology and Michael Tomasello of the Max Planck Institute for Evolutionary Anthropology.
In one example of the social learning tasks, a researcher demonstrated how to pop open a plastic tube to retrieve food or a toy inside. The children watched and copied. The chimps and orangutans did not imitate the researcher and instead tried to break the tube or pull the contents out with their teeth.
The tests took between three and five hours and were spread between five and eight days over two weeks. The apes were tested in the sanctuaries where they live in Africa and Indonesia.
The researchers plan to test other closely related species with the Primate Cognition Test Battery to map out the evolution of cognitive ability through systematically testing a variety of primate species and eventually comparing their genomes as they become available.
Reference: "Humans Have Evolved Specialized Skills of Social Cognition: The Cultural Intelligence Hypothesis," by Esther Herrmann, Josep Call, Brian Hare and Michael Tomasello of Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany; María Victoria Hernández-Lloreda at Universidad Complutense de Madrid in Madrid, Spain; and Brian Hare at Duke University in Durham, North Carolina.
Note: This story has been adapted from a news release issued by American Association for the Advancement of Science.

Fausto Intilla

www.oloscience.com

Bonobo Handshake: What Makes Our Chimp-like Cousins So Cooperative?

Source:

http://www.sciencedaily.com/releases/2007/09/070903142204.htm

Science Daily — What’s it like to work with relatives who think sex is like a handshake, who organise orgies with the neighbours, and firmly believe females should be in charge of everything?

On September 11, researcher Vanessa Woods will journey to Lola ya Bonobo Sanctuary in Congo with colleagues from the Max Planck Institute in Germany to study our mysterious cousin, the bonobo.
‘On our last trip, we found that bonobos were better cooperators than chimpanzees because they had sex and played a lot. This time we want to see how much thinking is going on behind the cooperation.’
Bonobos, like chimpanzees, are related to humans by 98.7%. But in contrast to chimpanzees who live in male dominated societies, where infanticide and lethal aggression are observed, bonobos live in highly tolerant and peaceful societies due to female dominance that maintains group cohesion and regulates tensions through sexual behaviour.
‘We’re always comparing ourselves to chimpanzees, but they’re only half the picture. Bonobos and chimpanzees are so opposite in many ways, that we really need to understand bonobos if we’re ever going to understand ourselves.’
Apart from cooperation, Woods and her colleagues will be looking at whether bonobos are more helpful than chimpanzees, whether bonobos are more helpful, and whether they like to play ball.
‘A lot of our experiments look silly, like when I throw a bright red soccer ball back and forth, or wave a red porcupine around. But a lot of these games help us understand the way bonobos think. Are they as obsessed with objects as we are? Are they scared of new things?’
Working in the Democratic Republic of Congo doesn’t always go according to plan.
‘Every day there seems to be a new crisis. Last trip we were evacuated from the sanctuary because of gunfire in Kinshasa. Then an orphan bonobo was confiscated from the bush meat trade. He died soon after. It was heart wrenching. But then the bonobos are so funny and fascinating, you go from being devastated one minute to uplifted the next.’
Note: This story has been adapted from a news release issued by Max Planck Institute.

Fausto Intilla

www.oloscience.com