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Marmoset monkeys chat politely, scientists say

Oct. 18, 2013
Courtesy of Cell Press
and World Science staff

Hu­mans aren’t the only spe­cies that knows how to car­ry on po­lite con­versa­t­ion, sci­en­tists re­port. Mar­mo­set mon­keys, too, will en­gage one an­oth­er for up to 30 min­utes at a time in vo­cal turn-taking, ac­cord­ing to ev­i­dence de­scribed in the jour­nal Cur­rent Bi­ol­o­gy on Oct. 17.

“We were sur­prised by how re­liably the mar­mo­set mon­keys ex­changed their vo­cal­iz­a­tions in a co­op­er­a­tive man­ner, par­tic­u­larly since in most cases they were do­ing so with in­di­vid­u­als that they were not pair-bonded with,” said Asif Ghaz­an­far of Prince­ton Uni­vers­ity, a co-author of the stu­dy.

“This makes what we found much more si­m­i­lar to hu­man con­versa­t­ions and very dif­fer­ent from the co­or­di­nated call­ing of an­i­mals such as birds, frogs, or crick­ets, which is linked to mat­ing or ter­ri­to­rial de­fense.”

Both peo­ple and mar­mo­sets seem to be will­ing to “talk” to just about an­y­one, and with­out rude in­ter­rup­tions, he said. The discovery makes mar­mo­sets rath­er un­ique, he added, not­ing that chimps and oth­er great apes “not only don’t take turns when they vo­calize, they don’t seem to vo­calize much at all, pe­ri­od!”

Ghaz­an­far and co-author Dan­iel Taka­hashi got in­ter­est­ed in mar­mo­sets be­cause of two fea­tures they hold in com­mon with peo­ple: they’re gen­er­ally friendly with one an­oth­er and com­mu­ni­cate mainly through vo­cal sounds. The sci­en­tists sus­pected that those fea­tures would sup­port the self-monitored give-and-take that a good con­versa­t­ion re­quires.

To find out, they placed mar­mo­sets in op­po­site corners of a room in which they could hear but not see each oth­er and recorded the ex­changes that en­sued. They found that mar­mo­sets don’t call at the same time, but rath­er wait for about five sec­onds af­ter one is fin­ished call­ing to re­spond.

Fur­ther study of the mar­mo­sets could help to ex­plain not only why hu­mans com­mu­ni­cate with each oth­er as they do but al­so why con­versa­t­ion can some­times break down, the in­ves­ti­ga­tors pro­posed. “We are cur­rently ex­plor­ing how very early life ex­pe­ri­ences in mar­mo­sets—including those in the womb and through to parent-infant vo­cal in­ter­ac­tions—il­lu­mi­nate what goes awry in hu­man com­mu­nica­t­ion dis­or­ders,” Ghaz­an­far said.


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Humans aren’t the only species that knows how to carry on polite conversation, scientists report. Marmoset monkeys, too, will engage one another for up to 30 minutes at a time in vocal turn-taking, according to evidence described in the journal Current Biology on Oct. 17. “We were surprised by how reliably the marmoset monkeys exchanged their vocalizations in a cooperative manner, particularly since in most cases they were doing so with individuals that they were not pair-bonded with,” said Asif Ghazanfar of Princeton University, a co-author of the study. “This makes what we found much more similar to human conversations and very different from the coordinated calling of animals such as birds, frogs, or crickets, which is linked to mating or territorial defense.” In other words, both people and marmosets seem to be willing to “talk” to just about anyone, and without rude interruptions. The discovery makes marmosets rather unique, the researchers say, noting that chimps and other great apes “not only don’t take turns when they vocalize, they don’t seem to vocalize much at all, period!” Ghazanfar and co-author Daniel Takahashi got interested in marmosets because of two features they hold in common with people: they’re generally friendly with one another and communicate mainly through vocal sounds. The scientists suspected that those features would support the self-monitored give-and-take that a good conversation requires. To find out, they placed marmosets in opposite corners of a room in which they could hear but not see each other and recorded the exchanges that ensued. They found that marmosets don’t call at the same time, but rather wait for about five seconds after one is finished calling to respond. Further study of the marmosets could help to explain not only why humans communicate with each other as they do but also why conversation can sometimes break down, the investigators proposed. “We are currently exploring how very early life experiences in marmosets—including those in the womb and through to parent-infant vocal interactions—can illuminate what goes awry in human communication disorders,” Ghazanfar said.