Department of Psychology, Georgia State University, Atlanta.
Am J Primatol. 2011 Oct;73(10):989-96. doi: 10.1002/ajp.20964. Epub 2011 May 16.
Copulation preferences in our closest living relative, the chimpanzee, suggest that males prefer older females who have had previous offspring. However, this finding is counter to some behavioral models, which predict that chimpanzee males, as promiscuous breeders with minimal costs to mating, should show little or no preference when choosing mating partners (e.g. should mate indiscriminately). To determine if the preferences indicated by copulations appear in other contexts as well as how they interact, we examined how male chimpanzees' grooming patterns varied amongst females. We found that males' preferences were based on interactions among females' fertility status, age, and parity. First, grooming increased with increasing female parity. We further found an effect of the estrous cycle on grooming; when females were at the lowest point of their cycle, males preferentially groomed parous females at peak reproductive age, but during maximal tumescence, males preferred the oldest multiparous females. Nulliparous females received relatively little grooming regardless of age or fertility. Thus, male chimpanzees apparently chose grooming partners based on both female's experience and fertility, possibly indicating a two-pronged social investment strategy. Male selectivity seems to have evolved to effectively distribute costly social resources in a pattern which may increase their overall reproductive success.
在我们最亲近的近亲——黑猩猩中，交配偏好表明雄性更喜欢有过后代的年长雌性。然而，这一发现与一些行为模型相悖，这些模型预测，作为滥交的繁殖者，雄性黑猩猩与交配相关的代价最小，在选择交配伴侣时应该几乎没有偏好（例如，应该滥交）。为了确定交配中表现出的偏好是否也存在于其他情况下，以及它们如何相互作用，我们检查了雄性黑猩猩的梳理模式在雌性之间是如何变化的。我们发现，雄性的偏好是基于雌性生育能力、年龄和生育次数的相互作用。首先，梳理行为随着雌性生育次数的增加而增加。我们还发现了发情周期对梳理行为的影响；当雌性处于周期的最低点时，雄性优先梳理处于最佳生育年龄的多产雌性，但在最大肿胀期，雄性更喜欢最年长的多产雌性。未生育的雌性无论年龄或生育能力如何，都很少得到梳理。因此，雄性黑猩猩显然是根据雌性的经验和生育能力来选择梳理伙伴的，这可能表明它们有一种双重的社会投资策略。雄性的选择性似乎是为了有效地分配昂贵的社会资源而进化出来的，这种策略可能会增加它们的整体繁殖成功率。
