Bardi Massimo, Prugh Adrianna M, Eubanks Bryon T, Trexler Kristen, Bowden Rachel L, Evans Sian, Lambert Kelly G, Huffman Michael A
Randolph-Macon College, Behavioral Neuroscience, Ashland, Virginia;, Email:
Randolph-Macon College, Behavioral Neuroscience, Ashland, Virginia.
J Am Assoc Lab Anim Sci. 2017 Nov 1;56(6):718-728.
Interactions between adult males and immature members of the same species are rare in most mammals; in contrast, an estimated 40% of primate species are characterized by an involvement of males in the social life of infants and juveniles. The proximate mechanisms of male-infant interactions are largely unstudied, and very few direct benefits for males have been proposed, especially in uniparental species in which the identity of the male parent is uncertain. In this study, we aimed to assess the relationship among behavioral and physiologic stress, health, and various affiliative behaviors initiated by adult males toward infants and juveniles in long-tailed macaques. We hypothesized that males that spent more time with infants and juveniles would have lower physiologic and social stress and better health than males with less interaction. We observed 2 troops of macaques with established social hierarchies (n = 18 in troop 1 and n = 8 in troop 2), each occupying a stable area within the enclosure, for more than 200 h. Fecal samples were used to assess cortisol levels as a measure of physiologic stress, and blood samples were collected to measure oxytocin levels as an index of social responsiveness. Our results indicated that male affiliative behavior directed toward immature animals was significantly higher in the troop characterized by more social conflicts; midranking males interacted more with infants than high- and low-ranking males in both troops. Furthermore, the DHEA:cortisol ratio, a physiologic index of resilience and coping, was positively correlated with males' affiliative responses, suggesting a neuroprotective role of male-infant interactions. In summary, our data support a proximate mechanism of alloparenting or paternal behavior in uniparental species. Interacting with infants and juveniles could provide an immediate neurobiologic benefit to adult males by facilitating adaptive coping responses to social tensions.
在大多数哺乳动物中，成年雄性与同一物种的未成年个体之间的互动很少见；相比之下，估计有40%的灵长类物种的特点是雄性参与婴儿和幼崽的社会生活。雄性与婴儿互动的近因机制在很大程度上尚未得到研究，而且很少有人提出雄性能从中获得直接益处，尤其是在单亲物种中，雄性亲本的身份并不确定。在本研究中，我们旨在评估行为和生理应激、健康状况以及成年雄性长尾猕猴对婴儿和幼崽发起的各种亲和行为之间的关系。我们假设，与婴儿和幼崽相处时间更长的雄性，其生理和社会应激水平会比互动较少的雄性更低，健康状况也更好。我们观察了2群具有既定社会等级制度的猕猴（第1群有18只，第2群有8只），每群都占据围栏内的一个稳定区域，观察时间超过200小时。粪便样本用于评估皮质醇水平，作为生理应激的指标，采集血液样本测量催产素水平，作为社会反应性的指标。我们的结果表明，在社会冲突较多的群体中，雄性对未成年动物的亲和行为明显更高；在两群猕猴中，处于中等地位的雄性比高地位和低地位的雄性与婴儿的互动更多。此外，脱氢表雄酮与皮质醇的比率，一种恢复力和应对能力的生理指标，与雄性的亲和反应呈正相关，表明雄性与婴儿的互动具有神经保护作用。总之，我们的数据支持了单亲物种中异亲抚育或父性行为的近因机制。与婴儿和幼崽互动可以通过促进对社会紧张局势的适应性应对反应，为成年雄性提供直接的神经生物学益处。
