Parity modifies endocrine hormones in urine and problem-solving strategies of captive owl monkeys (Aotus spp.)

Parental behavior modifies neural, physiologic, and behavioral characteristics of both maternal and paternal mammals. These parenting-induced modifications extend to brain regions not typically associated with parental responses themselves but that enhance ancillary responses, such as foraging efficiency and predator avoidance. Here we hypothesized that male and female owl monkeys (Aotus spp.) with reproductive experience (RE) would demonstrate more adaptive ancillary behavioral and neuroendocrine responses than those of their nonRE counterparts. To assess cognitive skills and coping flexibility, we introduced a foraging strategy task, including a set of novel objects (coin holders) marked with different symbols representing different food rewards, to the animals. To assess endocrine responses, urine samples were assayed for cortisol and dehydroepiandrosterone (DHEA) levels and their ratios to determine physiologic measures of emotional regulation in RE and nonRE owl monkeys. Compared with nonRE monkeys, experienced parents had higher DHEA:cortisol ratios after exposure to habituation training and on the first day of testing in the foraging task. Both hormones play critical roles in the stress response and coping mechanisms, and a high DHEA:cortisol ratio usually indicates increased coping skills. In addition, RE monkeys exhibited more efficient foraging responses (by 4-fold) than did the nonRE mating pairs. We conclude that RE modifies relevant behavioral and hormonal responses of both maternal and paternal owl monkeys exposed to a challenging cognitive paradigm. Corroborating previous research demonstrating adaptive modifications in foraging efficiency and emotional responses in reproductively experienced rodents, the current results extend these findings to a monogamous primate species.