Nasopalatine ducts and flehmen behavior in the mandrill (Mandrillus sphinx): Reevaluating olfactory communication in primates.

Compared to other modes of communication, chemical signaling generally has been overlooked in Old World primates, despite the presence in this group of secretory glands and scent-marking behavior, as well as the confirmed production and perception of conspecific olfactory signals. In other mammalian species, flehmen is a behavior thought to transport nonvolatile, aqueous-soluble odorants via specialized ducts to the vomeronasal organ (VNO). By contrast, Old World primates are traditionally thought to lack a functional VNO, relying only on the main olfactory system to process volatile odorants from their environment. Here, in the mandrill (Mandrillus sphinx), we document unusual morphological and behavioral traits that typically are associated with the uptake of conspecific chemical cues for processing by an accessory olfactory system. Notably, both sexes possess open nasopalatine ducts and, in response to the presentation of conspecific odorants, show stereotyped behavior consistent with the flehmen response. Flehmen occurred more frequently in response to odorants derived from male, as opposed to female, conspecifics and to odorants derived during the breeding season than the birthing season, suggesting a possible role in mediating social or reproductive information. Although confirming a link between the nasopalatine ducts, flehmen behavior, and olfactory processing in mandrills would require further study, our observations provide new information to suggest anatomical variability within Old World primates, calling further attention to the underappreciated role of chemical communication in this lineage.

Duke Scholars

Author Christine M. Drea Evolutionary Anthropology