Infanticide and Male-Female 'Friendships' in Savanna Baboons

这个项目解决了灵长类生物学的两个基本问题。 首先，为什么成年男性和女性有着持久的联系？ 在大多数哺乳动物物种中，两性在雌性发情期或生育期前后亲密互动;之后，雄性和雌性通常追求基本上独立的生活。 然而，在灵长类动物中，雄性和非生育（无动情期）雌性之间的永久性联系不仅比一般哺乳动物更常见，而且几乎是所有猴子和猿类的规则。 然而，灵长类动物中男女关系普遍存在和变化的进化原因仍然未知。 第二，为什么杀婴是某些雄性的生殖策略，而不是其他的？ 杀婴，即杀害依赖他人的婴儿（通常是男性），在哺乳动物中普遍存在，但表达较少。 这两个看似无关的问题在一个新的理论中结合在一起，提出男性和女性彼此形成社会关系，以保护年轻人免受杀戮。研究人员将在对两种密切相关的热带草原狒狒的研究中验证这一假设，这两种狒狒既有相似之处，也有重要的差异。 肯尼亚的橄榄狒狒（Papio cynocephalus anubis）和博茨瓦纳的查克玛狒狒（P. cynocephalus ursinus）都生活在大型的多雄性、多雌性群体中，哺乳期的雌性狒狒与特定的雄性狒狒保持密切的联系-俗称“友谊”。 然而，雄性狒狒杀婴在查克马狒狒中很常见，但在橄榄狒狒中很少见。 通过对这两个种群的比较研究，研究人员将回答以下问题：（1）雄性狒狒如何从友谊行为中受益：雄性狒狒是朋友的婴儿的遗传父亲，还是像橄榄狒狒那样，它们照顾无关的婴儿，因为母亲会选择他们作为未来后代的父亲？(2)雌性狒狒如何从与雄性狒狒的友谊中获益：它们是否在查克玛狒狒中获得了雄性的反性骚扰保护，而在不那么嗜性骚扰的橄榄狒狒中获得了其他一些好处（如免受雄性对雌性的骚扰）？(3)男性和女性之间的关系是否因男性对女性婴儿的父亲身份而有所不同，以及女性从两个人群中的友谊中获得的不同利益而有所不同？(4)杀虫剂能提高雄性非洲大狒狒的繁殖成功率吗？(5)为什么一些（但不是全部）雄性查克玛狒狒在达到统治等级中的阿尔法地位时会成为杀人狂，而很少有雄性橄榄狒狒会这样做？ 最终，对非人类灵长类动物的研究可能会提高我们对我们自己物种中性别之间社会关系的理解。

This project addresses two fundamental questions about primate biology. First, why do adult males and females share enduring bonds? In the majority of mammalian species, the sexes interact affiliatively around the period of female estrus or fertility; after that, males and females typically pursue largely separate lives. In primates, however, permanent association between males and nonfertile (anestrous) females is not only more common than in mammals generally, it is the rule in virtually all monkeys and apes. The evolutionary reasons for the ubiquity and variability of female-male relations in primates remain unknown, however. Second, why is infanticide a reproductive strategy of some males, but not others? Infanticide, the killing of dependent infants (usually by males), is widespread but variably expressed in mammals. These two apparently unrelated questions are united in a new theory that proposes that males and females form social relationships with one another in order to protect young against infanticide. The researchers will test this hypothesis in a study of two closely related savanna baboons that share similarities as well as important differences. The olive baboons (Papio cynocephalus anubis) of Kenya and the chacma baboons (P. cynocephalus ursinus) of Botswana both live in large, multi-male, multi-female groups in which lactating females maintain close bonds with particular males--popularly known as "friendships". Infanticide by males, however, is common in chacma baboons, but rare in olives baboons. By comparatively studying both populations, the researchers will answer the following questions: (1) how do males benefit from friendship behavior: are males the genetic fathers of their friends' infants, or, as argued for olive baboons, do they care for unrelated infants because mothers will then choose them as sires of future offspring?; (2) how do females benefit from friendships with males: do they obtain male anti-infanticide protection in chacma baboons, and some other benefit (such as protection from male harassment directed at females) in the less infanticidal olive baboon?; (3) do bonds between males and females vary in light of the male's paternity of the female's infant and due to the different benefits females may derive from friendships in the two populations? (4) does infanticide increase the reproductive success of male chacma baboons?; (5) why do some (but not all) male chacma baboons become infanticidal when reaching alpha status in the dominance hierarchy, whereas few male olive baboons ever do? Ultimately, the study of a nonhuman primate may improve our understanding of social relationships between the sexes within our own species.