How food availability facilitates cultural transmission in wild orangutans

The proverb “necessity is the mother of invention” has been used to explain the origins of our cultural evolution. After all, the needs of times of scarcity have forced humans to continually invent new technologies, which has propelled our species’ amazing cumulative culture. However, an invention becomes cultural only when it is learned and disseminated by many people. In other words, inventions need to be socially communicated.

But what are the forces driving social transmission? A long-term study of 18 years of data on wild orangutans suggests the answer may be found in the animals’ environments and the availability of their respective resources. suggests that there is.The research will be published in a journal iscience.

A team from two Max Planck Institutes and the University of Leipzig investigated how male orangutans learn from other orangutans, and found that individuals raised in food-rich habitats were more attentive to social cues. We found that there is a high tendency to This finding shows how an animal’s ecology can influence its opportunities for social learning, and thus new behaviors are likely to be innovations with cultural characteristics. is shown.

“We show that an animal’s ecological environment and the availability of its respective resources have knock-on effects not only on an individual’s social learning opportunities, but also on their evolutionary propensity for social learning. ” said lead author Julia Marchen.

A team from the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) and the Institute for Animal Behavior (MPI-AB) and the University of Leipzig (UL) studied adult males from wild populations in Borneo and Sumatra. I studied orangutans. “Thanks to their unique life history, adult males provide unique insights into social learning in orangutans,” says Märchen, a PhD student at the University of Leipzig.

Once males reach independence, they leave their natal habitat and spend the rest of their lives as nomads roaming the rainforest. “This means men are like eternal tourists, so they must constantly learn important behaviors from experienced locals, such as which foods are safe to eat. “No,” Marchen said. To learn the necessary new skills, migrant men observe resident orangutans in a behavior known as “peering.”

Researchers studied orangutans on the islands of Borneo and Sumatra and collected data on instances of male immigrant males staring at local residents. In both populations, males were found to spend more time near other individuals and more time looking at them when food was more abundant in the environment. The authors say this provides evidence that an animal’s environment can modulate social learning.

“During good times, orangutans spend more time in close quarters, which increases opportunities for social learning,” Marchen said.

This finding was further deepened when the researchers compared immigrant men from Sumatra and Borneo to see how peering rates differed. Sumatran orangutans live in habitats with abundant food supplies, while the Borneo population lives in fluctuating environments with low food availability. Not surprisingly, Sumatran males spent more time staring at each other than Borneo males. However, this finding persisted even after accounting for the influence of food availability.

“It’s not just that the Sumatran males spent more time peeping because there was more food around,” Marchen said. “We found that men in Sumatra were more likely to stare overall than men in Borneo.”

The authors note that their study cannot elucidate the mechanisms that cause differences in the tendency to pay attention to social information. “This could be the result of developmental influences in Bornean and Sumatran orangutans growing under different ecological conditions,” Marchen says. “Alternatively, it could be the result of genetic differences between species that separated about 674,000 years ago, or a combination of both.”

“Our study provides a glimpse into how ecology influences cultural transmission,” said MPI-AB senior author Caroline Spree. “It modulates opportunities for social learning and thus shows the extent to which new behaviors change the likelihood of becoming enculturated.”

Anja Widig, senior author of MPI-EVA and UL, said: “The discovery of such an effect of general food availability on social tolerance “Studies in great apes show deep evolutionary origins of ecological influences.” On the propensity for social learning in the hominid lineage and its potential presence in other lineages. ”