Monkey communication expert Robert Seyfarth began his lecture on May 5, the kick-off of the University of Delaware's Year of Darwin celebration, with a true story, documented in 1961, about a female baboon that herded goats in an African village.
The baboon knew all of the relationships between the goats so well that at night she would carry a bleating kid from one barn directly to its mother in another barn.
“For all the centuries we've bred dogs, no dog has exhibited this knowledge of kids and mothers,” said Seyfarth, who is a psychology professor at the University of Pennsylvania. “The question is where does this mind come from?”
Seyfarth transported an audience of about 200 people into the fascinating world of the baboons of Botswana's Okavanga Delta, which he and Dorothy Cheney, his research partner, fellow Penn professor, and spouse, studied from 1992 to 2008.
Based on their research, Seyfarth said, he and Cheney argue that the baboon's ability to recognize social relationships is due to natural selection. This is the process in nature, according to Darwin's theory of evolution, in which only the organisms best adapted to their environment tend to survive and reproduce.
The baboons that Seyfarth and Cheney studied live in groups of 80-90 individuals. Males leave the group in which they are born, while females stay in the group for their entire lives, with close bonds to female relatives.
The females are arranged in a matrilineal hierarchy of families, with ranks maintained for years. Although once in a while a coup is attempted, such moves are not often successful.
“Families stick together,” Seyfarth said. “The rules are, like in a Jane Austen novel, be nice to your relatives and get in with the high-ranking relatives.”
In their experiments, Seyfarth and Cheney observed baboons with names such as Sylvia, Champagne, and Helen, and recorded their language, which consists of no more than 18 sounds, and the interactions of their families.
They found that baboons use certain calls only in certain contexts. Screams and fear barks are only given from a lower-ranking to a higher-ranking baboon, while threat grunts are given only from a higher-ranking to a lower-ranking baboon.
By recording the various calls and then playing them in situations that “break the rules,” the scientists determined from the animals' behavior that baboons are able to put together the discrete elements of identity, kinship, and rank.
“The animals somehow see this world in all of its complexity,” Seyfarth said.
“It's an innate property of the baboon mind -- done instantly and unconsciously,” he noted.
What social factors stress baboons? Seyfarth and Cheney were able to measure the animals' stress levels by analyzing fecal samples for gluccocorticoid stress hormones.
They found that pregnancy and incidences of predation are major stressors. Ninety-five percent of baboon deaths are caused by predators, mostly lions, Seyfarth said.
Also, some high-ranking males practice infanticide, targeting infants by rank. Mothers may form relationships with lower-ranking males who will help look after their babies.
And just as in humans, the loss of a close relative is high on the list, Seyfarth said.
“Females respond to stress by associating with their closest grooming relationships,” Seyfarth said. “They turn to their support network if they lose someone. They broaden and extend to replace old relationships with new ones. Female baboons with strong social bonds survive better,” he said.
This work is highlighted in the award-winning book Baboon Metaphysics: The Evolution of a Social Mind, published by the University of Chicago Press in 2007.
Additional support for the series is being provided by the Provost's Office, the College of Agriculture and Natural Resources, the Science Ethics and Public Policy Program, and the following departments: Biological Sciences, English, Geography, Geological Sciences, Linguistics and Cognitive Science, and Philosophy.
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