Olfactory evolution and behavioral ecology in primates

Abstract

Primates are usually thought of as "visual" mammals, and several comparative studies have emphasized the role of vision in primate neural and sociocognitive specialization. Here I explore the role of olfactory systems, using phylogenetic analysis of comparative volumetric data. The relative sizes of the main olfactory bulb (MOB) and accessory olfactory bulb (AOB) tend to show different evolutionary patterns in accordance with their different functions. Although there is some evidence of correlated evolution of the two systems, this is apparent in only one clade (the strepsirhines). As predicted, the MOBs correlate predominantly with ecological factors (activity period and diet), while the AOBs correlate with social and mating systems. Related olfactory structures (i.e., the piriform cortex and amygdala) exhibit correlated evolution with the AOBs but not with the MOBs, and the corticobasolateral part of the amygdala exhibits a correlation with social group size in platyrrhines similar to that observed for the AOB. These social system correlations support the idea that there is an olfactory dimension to the concept of the social brain.

Vision verbs dominate in conversation across cultures, but the ranking of non-visual verbs varies

“…Humans, like other primates, display considerable visual specialization including high visual acuity, stereoscopic vision, trichromacy, and large visual cortices (Barton 2006). Some estimates suggest that up to 50% of the cortex may be involved in visual function (Palmer 1999).…”

Foraging Cognition in Nonhuman Primates

“…It has also been noted that a variety of brain size variables in primates correlate positively with measures of social complexity, such as group size, deceptive behaviour, or strength of social bonds (Barton, 1996(Barton, , 1999Byrne & Corp, 2004;Dunbar, 1998;Dunbar & Shultz, 2007). This has been taken to suggest that large groups, and social complexity that emerges from them, have acted as a primary selection force favouring the evolution of increased brain size.…”

Sensory information and associative cues used in food detection by wild vervet monkeys

“…Species with such enhanced visual systems may predominantly rely on vision to locate food. In other species, scent may be most salient in locating food resources, depending on olfactory capacity (Smith and Rossie 2006;Barton 2006), the time of the day spent foraging (Charles-Dominique 1977;Pariente 1979), and the strength and reliability of an odor signal (Vickers 2000). Strepsirrhine primates retain the primitive primate rhinarium and the entire vomeronasal complex (reviewed in: Colquhoun 2011), so their detection of odorants may be greatest within the primate order (e.g., Rushmore et al 2012).…”