Socioendocrinology of Cooperative Offspring Care

在哺乳动物中，由雌性独家照料后代是常态，但在少数物种中，雄性和其他群体成员在抚养依赖的后代方面也发挥着重要的、潜在的关键作用。在新大陆灵长类动物绒猴和罗望鱼中，所有群体成员，包括母亲、父亲和非繁殖的幼体和亚成体的照顾，是社会群体的规范。之前NSF资助的结果显示，母亲和父亲在婴儿护理方面的努力水平存在重要差异，母亲在婴儿出生后的头两周在婴儿护理中发挥着重要作用，父亲和帮助者在婴儿生命的第三周和第四周及以后发挥核心作用。这些变化与母亲和父亲的睾酮(T)浓度变化有关：母亲在产后前两周睾酮(T)降低，父亲在产后第二个两周降低，这对应着最高的婴儿保育率。当前提案中概述的研究将利用观察和实验方法，研究睾酮浓度的变化是否有助于调节对绒猴婴儿的反应，以及T是否在婴儿护理努力与生殖和/或攻击性行为之间进行权衡，这可能与婴儿护理不相容。这一结果将阐明，社会性灵长类动物复杂的附属和照顾行为可能部分受到生物状态以及与经验相关的因素的影响。

Exclusive offspring care by females is the norm among mammals, but among a small set of species, males and other group members also play an important and potentially crucial role in the nurturing of dependent offspring. Among marmosets and tamarins, primates of the New World, care by all group members, including the mother, father, and nonbreeding juveniles and subadults, is the norm for social groups. Results from previous NSF funding have revealed important differences in levels of effort in infant care by mothers and fathers, with mothers playing a large role in infant care in the first two weeks of life, and fathers and helpers playing a central role in the 3rd and 4th weeks of infant life and beyond. These changes are associated with variations in testosterone (T) concentrations in mothers and fathers: T is reduced in mothers in the first 2 weeks post partum and in fathers during the second 2 weeks post partum, which corresponds to the highest rates of infant care. The studies outlined in the current proposal will utilize both observational and experimental approaches to the possibility that variation in testosterone concentrations helps regulate responsiveness to infants in marmosets, and whether T mediates a trade-off in effort in infant care versus reproductive and/or aggressive behaviors, which may be incompatible with infant care. The results will shed light on the possibility that complex affiliative and caregiving behaviors in social primates may, in part, be influenced by biological states, as well as experience-related factors.