Female rhesus macaque calls may reflect familiarity rather than relatedness

August 31, 2016

An acoustic analysis showed that similarities between contact calls - known as coos - of female rhesus macaques may be explained by familiarity rather than relatedness, according a study published August 31, 2016 in the open-access journal PLOS ONE by Dana Pfefferle from the Cognitive Neuroscience Laboratory of the German Primate Center, Germany, Kurt Hammerschmidt from the Cognitive Ethology Laboratory of the German Primate Center, Germany, and colleagues.

Previous work has suggested that non-human primates can recognize the coos of kin, though few have distinguished between relatedness and familiarity. To investigate whether call similarities actually reflect relatedness, Pfefferle, Hammerschmidt, and colleagues recorded and analyzed the acoustic structure of coos from 67 adult female rhesus macaques in a longstanding colony on the island of Cayo Santiago, Puerto Rico. The degree of relatedness was determined using the colony's long-term genetic database, and familiarity was determined using factors including age, group- and matrilineal membership.

Contrary to their expectations, the researchers found coo similarity was predicted by familiarity, but not by kinship: coo call structure was similar in females that were close in age or that shared group and matrilineal membership. This suggests that although these calls appear largely innate, experience and frequent social interaction have more impact on acoustic similarity than genetic background. To control for the strong effect of familiarity on the acoustic structure of calls, the researchers recommend that future studies focus on similarities between unfamiliar kin.

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