The evolution of pheromonal communication

Abstract

Small-brained rodents have been the principle focus for pheromonal research and have provided comprehensive insights into the chemosensory mechanisms that underpin pheromonal communication and the hugely important roles that pheromones play in behavioural regulation. However, pheromonal communication does not start or end with the mouse and the rat, and work in amphibians reveals much about the likely evolutionary origins of the chemosensory systems that mediate pheromonal effects. The dual olfactory organs (the main olfactory epithelium and the vomeronasal organ), their receptors and their separate projection pathways appear to have ancient evolutionary origins, appearing in the aquatic ancestors of all tetrapods during the Devonian period and so pre-dating the transition to land. While the vomeronasal organ has long been considered an exclusively pheromonal organ, accumulating evidence indicates that it is not the sole channel for the transduction of pheromonal information and that both olfactory systems have been co-opted for the detection of different pheromone signals over the course of evolution. This has also led to great diversity in the vomeronasal and olfactory receptor families, with enormous levels of gene diversity and inactivation of genes in different species. Finally, the evolution of trichromacy as well as huge increases in social complexity have minimised the role of pheromones in the lives of primates, leading to the total inactivation of the vomeronasal system in catarrhine primates while the brain increased in size and behaviour became emancipated from hormonal regulation.

New perspectives on anthropoid origins

“…Catarrhines are unique among primates in lacking functional VNOs (91,96). Early reports of a functional VNO in humans are controversial and have not been supported by subsequent anatomical research (97,98). Although some adult catarrhines (including humans) may express a rudimentary VNO, such structures do not contain a sensory epithelium, often do not communicate with the nasal fossa, and lack vomeronasal nerves to transmit information to the brain.…”

Contextual chemosensory urine signaling in an African cichlid fish

“…Chemosensory signaling is a key communication channel in fishes and has been best studied in the goldfish Carrasius auratus where both males and females release pheromones to prime the opposite sex and synchronize spawning (Dulka et al, 1987;Sorensen, 1992;Appelt and Sorensen, 1999;Stacey and Sorensen, 2005;Appelt and Sorensen, 2007;Stacey, 2011). Many other fish species also use pheromones to influence the behavior and physiology of conspecifics, which has important consequences for reproductive success Gerlach, 2006;Barata et al, 2008b;Barata et al, 2008a;Rosenthal et al, 2011), and this phenomenon is conserved through mammals (Dulac and Torello, 2003;Swaney and Keverne, 2009). One mode of pheromone release in fishes is via urine pulses; however, few studies have examined how individuals might alter their urine release for use as a contextual social signal.…”

The main and the accessory olfactory systems interact in the control of mate recognition and sexual behavior

“…Among the various communication strategies that have evolved in mammalian species, smell is surely the most widespread and the most conserved [106]. In the field of chemosensory communication, Karlson and Lüscher [43] introduced the concept of "pheromones" as chemosignals that provide information to conspecifics about sex or endocrine status or which stimulate hard-wired species-specific social behaviors.…”