Social animals benefit from their groupmates, so why do they sometimes kill each other’s offspring? Using 30 years of data from multiple groups of wild spotted hyenas, we address three critical aims for understanding infanticide in any species: (1) quantify the contribution of infanticide to overall mortality (2) describe the circumstances under which infanticide occurs and (3) evaluate hypotheses about the evolution of infanticide. We find that, although observed only rarely, infanticide is in fact a leading source of juvenile mortality. Infanticide accounted for 24% of juvenile mortality, and 1 in 10 hyenas born in our population perished due to infanticide. In all observed cases of infanticide, killers were adult females, but victims could be of both sexes. Of four hypotheses regarding the evolution of infanticide, we found the most support for the hypothesis that infanticide in spotted hyenas reflects competition over social status among matrilines.

中文翻译：

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雌性杀婴是大型社会食肉动物幼年死亡率的主要来源

群居动物从他们的群体中受益，那么为什么他们有时会杀死彼此的后代？使用来自多组野生斑点鬣狗的 30 年数据，我们解决了了解任何物种杀婴的三个关键目标：(1) 量化杀婴对总体死亡率的贡献 (2) 描述发生杀婴的情况和 (3)评估关于杀婴演变的假设。我们发现，尽管很少观察到，杀婴实际上是导致青少年死亡的主要原因。杀婴占青少年死亡率的 24%，我们人口中每 10 只鬣狗就有 1 只死于杀婴。在所有观察到的杀婴案件中，凶手都是成年女性，但受害者可能是两性的。在关于杀婴演变的四个假设中，