On Georgia island, clever lemurs get all the attention

In the lemur world, smarts could mean popularity.

New research found that lemurs spent more time with individuals who figured out how to complete a foraging challenge fastest.

“Lemurs tend to hang out with individuals that they learn from,” said Ipek Kulahci, first author on the paper published in Current Biology. “Being able to learn new information and adjust behavior based on this information has an influence on how well individuals are connected socially to their group members.”

A ring-tailed lemur opens a Plexiglas box to obtain the grape inside. ©Ipek Kulahci

Given lemurs’ imperiled status, Kulahci said, “their ability to find food, learn about predators, find resources or learn about each other has implications for how well they survive and reproduce. It’s important to understand their social lives and ability to learn about different aspects of their environments before we can make a decision about how to conserve animals in the wild.”

Endemic to Madagascar, ring-tailed lemurs (Lemur catta) are highly social primates that live in female-dominated groups of up to 25 called conspiracies. Endangered on their native island due to deforestation and the illegal pet trade, lemurs occupy several research sites in North America, such as St. Catherine’s Island in Georgia, where dozens of lemurs habituated to humans freely roam.

In 2014, Kulahci, then a doctoral candidate at Princeton University, and her co-authors studied social networks among 38 of these lemurs in two conspiracies on St. Catherine’s Island. Past research had established the significance of cognitive capacities and social connections for the survival and reproduction of primates and birds, she said, and it had focused on how social interactions impact learning.

To look at the other side of the coin, Kulahci’s team presented both groups with a grape in a transparent plastic box. The researchers watched as a young lemur in each conspiracy cracked the case by pulling open a drawer to obtain the fruit. After knowledge of how to manipulate the box spread as the lemurs observed one another getting their hands on the treat, the biologists examined the animals’ grooming interactions and physical proximity to their groupmates to determine how their social lives had been affected by the learning process.

One lemur grooms another to maintain their social bond.

“They interact more with successful individuals,” Kulahci said. “If I know something, and it’s beneficial for others to learn from me, they may adjust their social responses to spend more time with me so they have more opportunities to learn. Lemurs learning new behaviors is intertwined with who interacts with them. There seems to be a bidirectional relationship between learning and social behavior.”