New research published in the journal Animal Behaviour has revealed that lemur vocalizations have specific uses other than general communication, including improving the bonds between favored friends and family members within a clan. Since lemurs are a distant relative of humans, this implies that our ability to gossip could be a social bonding tool passed down from our very ancient primate ancestors.
The last common ancestor between lemurs and humans lived around 55 million years ago. Although human behavior is often compared to chimpanzees, with which we have a common ancestor only 13 million years ago, the social nature of lemurs isn’t actually too dissimilar to our own species. As they represent such an ancient evolutionary link with humans, their behaviors may reveal how far shared behavioral traits can be traced back in time.
Grooming is a common activity among lemurs. Far from just removing parasites, it also serves as a way of socially bonding with members of a group deemed more valuable to the groomer. The research team from Princeton, led by ecology and evolutionary biology doctoral student Ipek Kulahci, decided to investigate whether or not the vocalizations from lemurs also served the same purpose.
Image credit: Vocalization is even more selective than grooming, implying it represents a very exclusive type of social bonding. Ipek Kulahci
Groups of ringtailed lemurs at Duke University’s Lemur Center, and others on St. Catherine’s Island in Georgia, were chosen for this study. The team observed and recorded the vocalizations of individual lemurs, including those that seemed to be directed at a gathering of lemurs and those apparently directed at other individual lemurs. These recordings were also played back to both individuals and group members, and the team watched carefully to see how the lemurs responded.
The team found that lemurs that shared a close grooming relationship with the individual emitting the vocalization responded, regardless of whether they heard the call alone or in a large group. Even if the vocalizing lemur in question wasn’t nearby, and thus couldn’t be smelled or seen by the other lemur, it still responded to its call. This, the researchers believe, emphasizes that strong social bonds are indicated by these vocal exchanges.
“By exchanging vocalizations, the animals are reinforcing their social bonds even when they are away from each other,” Kulahci said in a statement. “This social selectivity in vocalizations is almost equivalent to how we humans keep in regular touch with our close friends and families, but not with everyone we know.”
However, two lemurs that groomed each other more did not necessarily vocalize to each other more often; vocalizations towards an individual could increase even if grooming frequency did not. This indicates that there is some independence between grooming and vocalization, hinting at a deeper, more complex social network within lemurs than previously assumed.
In any case, the researchers suggest that this mixture of verbal communication and physical grooming is similar to the way people use a combination of various verbal and physical actions to complement each other in everyday life. “We raise our voice and use our hands when making an emphatic point, but stick to voice only when not particularly excited or the situation is less urgent,” said Daniel Rubenstein, a professor of ecology and evolutionary biology and coauthor of the study.
So there you have it: Gossip and chitchat – touching base with our friends and family – could be an evolutionary trait many millions of years old.