Socioendocrinology of Cooperative Offspring Care

哺乳动物中只有雌性动物照顾后代是正常的，但在一小部分物种中，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和潜在的关键作用。 在新大陆的灵长类动物--绒猴和绢毛猴中，所有群体成员，包括母亲、父亲、未繁殖的幼猴和亚成年猴，都要照顾它们，这是社会群体的标准。 从以前的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前两周内在婴儿护理中发挥着重要作用，父亲和助手在婴儿出生后的第3周和第4周及以后发挥着核心作用。 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2周和父亲在产后后2周的T降低，这与婴儿护理率最高相对应。 当前提案中概述的研究将利用观察和实验方法来研究睾酮浓度的变化有助于调节绒猴对婴儿的反应的可能性，以及T是否介导婴儿护理与生殖和/或攻击行为之间的权衡，这可能与婴儿护理不相容。 这些结果将揭示社会灵长类动物复杂的亲和和亲和行为可能部分受到生物状态以及经验相关因素的影响。

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.