Sex-specific differences in olfactory sensitivity for putative human pheromones in nonhuman primates

Area of Science:

• Primate olfaction
• Neuroendocrinology
• Behavioral neuroscience

Background:

• Volatile C19-steroids, androsta-4,16-dien-3-one (AND) and estra-1,3,5(10),16-tetraen-3-ol (EST), influence human autonomic nervous system responses and hypothalamic activity in a gender-specific manner.
• Previous research indicates these steroids can modulate physiological and neural responses, suggesting a role in inter-species communication or sensory perception.

Purpose of the Study:

• To investigate olfactory sensitivity to AND and EST in nonhuman primates.
• To determine if sex-specific differences in sensitivity to these steroids exist in primate species.
• To explore the potential for bimodal distributions of olfactory sensitivity in nonhuman primates.

Main Methods:

• Two conditioning paradigms were employed to assess behavioral responses to AND and EST in pigtail macaques, squirrel monkeys, and spider monkeys of both sexes.
• Concentration-response relationships were established for steroid detection.
• Behavioral detection thresholds and response patterns were analyzed based on sex and species.

Main Results:

• Pigtail macaques and squirrel monkeys of both sexes detected AND and EST at micromolar and mM concentrations, respectively.
• Spider monkeys exhibited marked sex-specific differences in olfactory sensitivity.
• Male spider monkeys showed no behavioral response to high concentrations of AND, while female spider monkeys did not respond to high concentrations of EST.

Conclusions:

• This study presents the first evidence of sex-specific bimodal distributions of olfactory sensitivity in a nonhuman primate species.
• Spider monkeys display differential olfactory perception of C19-steroids based on sex.
• These findings contribute to understanding the evolution of olfactory systems and sex-specific sensory processing in primates.