Sources of variation in weaned age among wild chimpanzees in Gombe National Park, Tanzania
Sources of variation in weaned age among wild chimpanzees in Gombe National Park, Tanzania
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DOI：
10.1002/ajpa.23986
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发表时间：
2019-12-16
影响因子：
2.8
通讯作者：
Murray, Carson M.
中科院分区：
文献类型：
--
作者：
Lonsdorf, Elizabeth V.;Stanton, Margaret A.;Murray, Carson M.
目的人类生活史进化的一个重要特征是现代人比非洲猿类平均提前2-4年断奶。然而，我们对猿类断奶变异的了解仍然有限。在这里，我们通过使用坦桑尼亚贡贝国家公园的长期数据检查断奶年龄变化，在黑猩猩中提供了第一个这样的报告。材料与方法我们分析了29只母黑猩猩的65只后代41年的观察行为数据，分析了野生黑猩猩断奶年龄(定义为停止哺乳)与母体年龄、优势度和胎次以及后代性别的关系。我们使用具有混合效应的COX比例风险回归来模拟断奶时间，并检查后代断奶年龄的潜在变异来源。结果我们发现雄性后代比雌性后代在特定年龄断奶的可能性更小，雄性断奶年龄比雌性断奶年龄差异更大。此外，母体优势等级与子代年龄存在交互作用，即地位较低的母亲不太可能提前断奶，但这种影响随着子代年龄的增加而减弱。讨论我们发现，雄性后代和地位较低的雌性的后代不太可能提前断奶，但没有发现根据母亲的年龄或胎次进行可变断奶的证据。随着更多数据的积累，我们将能够更好地理清母亲主导地位、年龄和产次的影响。这样的研究不仅将提供对活猿生活史特征的更丰富的了解，也将为理解人类早期断奶的进化提供重要的框架。
Objectives A key feature of human life history evolution is that modern humans wean their infants 2-4 years earlier on average than African apes. However, our understanding of weaning variation in apes remains limited. Here we provide the first such report in chimpanzees by examining weaned age variation using long-term data from Gombe National Park, Tanzania. Material and Methods We analyzed 41 years of observational behavioral data from 65 offspring of 29 mothers to examine the relationships between weaned age (defined as cessation of suckling) in wild chimpanzees and maternal age, dominance rank and parity, and offspring sex. We used Cox proportional hazards regression with mixed effects to model time to weaning and to examine potential sources of variation in offspring weaned age. Results We found that male offspring were less likely than female offspring to wean by a given age and that weaned age of males varied more than weaned age of females. In addition, maternal dominance rank interacted with offspring age, such that low-ranking mothers were less likely to wean offspring early, but this effect decreased with offspring age. Discussion We found that male offspring and offspring of low-ranking females were less likely to wean early, but did not find evidence for variable weaning according to maternal age or parity. As more data accumulate, we will be better able to disentangle the effects of maternal dominance rank, age and parity. Such studies will not only provide a richer understanding of living ape life history characteristics, but will also provide an important framework for understanding the evolution of early weaning in humans.