Recent finds in hominin fossil environments place the transition to terrestriality in a wooded or forested habitat. Therefore, forest-dwelling apes can aid in understanding this important evolutionary transition. Sex differences in ape locomotion have been previously attributed to sexual dimorphism or ecological niche differences between males and females. This study examined the hypothesis that differential advantages of terrestrial travel may impact mating success in male bonobos. We examined whether males are more terrestrial when there are mating benefits for fast travel. We analyzed behavioral data on wild bonobos over a ten-month period in the Lomako Forest, DRC and examined the proportion of time spent at lower heights compared to higher heights between adult females and males relative to their location to feeding contexts with high mating frequencies. We found a significant interaction between sex and height class away from food patches (F=4.65, df =1, p <0.05) such that females were primarily arboreal whereas there was no difference between males across height classes. However, there was also a significant interaction between sex and height class (F =29.35, df =1, p <0.0001) for adults traveling near or entering a food patch. Males often arrived at food patches terrestrially and females arrived almost exclusively arboreally. We found a significant difference between the expected and observed distribution of matings by food patch context (G =114.36, df =4, p <0.0001) such that most mating occurred near or in a food patch. These results suggest that males may travel terrestrially to arrive at food patches before cohesive parties of females arrive arboreally, in order to compete with other males for mating access to these females. Such intrasexual selection for sex differences in locomotion may be important in considerations of the evolution of locomotion strategies in hominins in a forested environment.

中文翻译：

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倭黑猩猩（Pan paniscus）陆地性的性别差异：对人类进化的影响。

最近在古人类化石环境中的发现将过渡到树木繁茂或森林覆盖的栖息地。因此，森林栖息的猿类可以帮助理解这一重要的进化转变。猿类运动的性别差异以前被归因于雄性和雌性之间的性别二态性或生态位差异。这项研究检验了陆地旅行的不同优势可能会影响雄性倭黑猩猩的交配成功的假设。我们研究了当快速旅行有交配好处时，雄性是否更加陆生。我们分析了洛马科森林 10 个月内野生倭黑猩猩的行为数据，DRC 并检查了成年雌性和雄性之间相对于其位置与高交配频率的喂养环境相比，在较低高度上花费的时间与较高高度相比的时间比例。我们发现性别和远离食物斑块的身高等级之间存在显着的相互作用（F = 4.65，df = 1，p <0.05），因此女性主要是树栖，而不同身高等级的男性之间没有差异。然而，对于靠近或进入食物带的成年人，性别和身高等级之间也存在显着的相互作用（F = 29.35，df = 1，p <0.0001）。雄性经常在陆地上到达食物区，而雌性几乎完全在树上到达。我们发现食物补丁背景下的预期和观察到的交配分布之间存在显着差异（G = 114.36，df = 4，p <0。0001），因此大多数交配发生在食物补丁附近或内。这些结果表明，为了与其他雄性竞争与这些雌性交配的机会，雄性可能会在有凝聚力的雌性群体到达树栖之前在陆地上旅行到达食物区。考虑到森林环境中人类运动策略的演变，这种对运动性别差异的性内选择可能很重要。