FScientists at Princeton University discover that marmosets call and then listen to each other in new research that recorded the animals calling to one another from opposite corners of a room. The lead researcher, Daniel Takahashi, recorded the marmosets separated by a curtain, so they could hear but not see each other.
Marmosets, a group of monkeys that include some 22 species, are 8-inch-long, furry monkeys native to South America. This new study shows that these mammals can continue extended, back-and-forth discussions without interrupting one another. Humans are the only other primate capable of this kind of conversation.
Marmosets are viewed as “primitive” because they have claws rather than nails, and do not have opposable thumbs. But when it comes to socializing and listening, these primitive primates appear advanced. And they engage in cooperative breeding. Asif Ghazanfar, a primate neurobiologist at Princeton University attempts to understand the evolutionary and developmental bases for communication in humans. Results from this study are reported in the journal Current Biology.
The study recorded the five second delay after one animal finished calling before responding… These vocal turn-taking sessions sometimes lasted 30 to 40 minutes. Ghazanfar pointed out that the dyads didn’t always make one statements before waiting. Sometimes they would make more calls before waiting.
The researchers claim that even though the monkey vocal sounds are simple to the human ear, they contain important information about identity, gender, social group and context. This vocal turn-taking may help the animals exchange information. If the marmosets were constantly interrupting each other in the wild, it would be difficult for information to be exchanged, especially in a sound-filled forest environment.
Ghazanfar chose Marmosets for the study because these mammals are more vocal than other monkeys. Friendly and talkative, Marmosets communicate even when they’re out of sight of each other. Given these cooperative traits, Ghazanfar and his colleagues speculated whether the monkeys would exhibit vocal turn-taking to enhance their cooperation.
Ghazanfar explained some reasons as to why the animals follow these rules.
One cause could be their small size. Ghazanfar told BBC news that their size makes them more vulnerable to predators. As a natural defense, marmosets almost always give birth to twins or triplets. “But this is very different from other primate species and required them to adopt a different care strategy,” Ghazanfar said in an interview with 109 News. He added that the mothers needed help taking care of the multiple babies, so the fathers and other monkeys in the group assisted.
Another reason would be to establish contact .when they are separated from group members and want to establish contact with another. “You only know if you’ve established that contact if their response is contingent on your own,” Ghazanfar explained to BBC News.
Another primary hypothesis is that Marmosets have information content they want to share.
Ghazanfar is hypothesizing that human turn-taking might have evolved through a similar route, on a parallel branch of the evolutionary tree.
His reasoning proposes another alternative explanation to the “mysterious step” of how human communication developed. It is hypothesized that these patterns of chimp-like gestural exchanges evolved into the patterns of human vocal communication. There are scientists who disagree that this “leap” could have ever occurred, not only because of the complexity of words and language processing in humans, but because of the higher thinking abilities in moral choices of humans.
Chimpanzees, viewed as the closest primate relatives, do not call or listen to each other but use gestures to communicate, so evolutionary scientists have generally proposed that that these manual gestures provide the rudimentary start of evolving into human communication, a view that some traditionalists, even some who aren’t even conservative or Christian, oppose.. Thomas Nagel wrote Mind and Cosmos: Why the Materialist Neo-Darwinian Conception of Nature Is Almost Certainly False. This philosopher has come to the conclusion that confining our views of life into measurable quantities does not work. Using studies of chimps to prove that morality – or human communication – has a genetic component in humans will not be a widely accepted conclusion among all scientists, and the debate will continue to separate groups of scientists.
Written By: Danelle Cheney