Researchers have long been interested in the noises that non-human primates make and how they are used for communication. Monkey vocalizations could be carrying information that the sender expects the recipient to understand, or they could be noises that the recipient can draw inferences from, but are not intended to carry information. A human sneeze, for instance, is a noise that people understand may be associated with a cold, but it did not develop evolutionarily to convey information.
The study by Maestripieris team showed that the grunts and girneys emitted by the rhesus macaques fall into the category of vocalizations not intended to convey specific information, and appear to be used to attract other individuals attention or change their emotional states. When females vocalize to young infants, however, the infants mothers infer that the females simply want to play with the infants and are unlikely to harm them. Therefore, these vocalizations may facilitate adult females interactions not only with infants, but with the infants mothers as well. They found, for instance, that the grunts and girneys were sometimes followed by an approach and grooming of the mothers.
Additionally they discovered that, unlike human mothers, the rhesus macaque mothers did not direct grunts or girneys toward their own offspring. It could be that the monkey mothers are familiar with their own offspring and use the vocalizations with other babies because they are excited about the novelty of seeing a new infant, Maestripieri said.
|Contact: William Harms|
University of Chicago