Background/Aims: Substantive sex differences in behavior and cognition are found in humans and other primates. However, potential sex differences in primate neuroanatomy remain largely unexplored. Here, we investigate sex differences in the relative size of the cerebellum, a region that has played a major role in primate brain evolution and that has been associated with cognitive abilities that may be subject to sexual selection in primates. Methods: We compiled individual volumetric and sex data from published data sources and used MCMC generalized linear mixed models to test for sex effects in relative cerebellar volume while controlling for phylogenetic relationships between species. Given that the cerebellum is a functionally heterogeneous structure involved in multiple complex cognitive processes that may be under selection in males or females within certain species, and that sexual selection pressures vary so greatly across primate species, we predicted there would be no sex difference in the relative size of the cerebellum across primates. Results: Our results support our prediction, suggesting there is no consistent sex difference in relative cerebellum size. Conclusion: This work suggests that the potential for sex differences in relative cerebellum size has been subject to either developmental constraint or lack of consistent selection pressures, and highlights the need for more individual-level primate neuroanatomical data to facilitate intra- and inter-specific study of brain sexual dimorphism.
Brain Behav Evol

中文翻译：

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灵长类动物的相对小脑大小不是性别二态的。

背景/目的：在人类和其他灵长类动物中发现了行为和认知方面的实质性性别差异。然而，灵长类动物神经解剖学的潜在性别差异在很大程度上仍未得到探索。在这里，我们调查了小脑相对大小的性别差异，该区域在灵长类动物的大脑进化中发挥了重要作用，并且与可能受灵长类动物性选择影响的认知能力有关。方法：我们从已发布的数据源中汇编了个体体积和性别数据，并使用 MCMC 广义线性混合模型来测试相对小脑体积的性别效应，同时控制物种之间的系统发育关系。鉴于小脑是一个功能异质结构，涉及多个复杂的认知过程，某些物种的雄性或雌性可能受到选择，而且灵长类动物的性选择压力差异很大，我们预测在灵长类动物小脑的相对大小。结果：我们的结果支持我们的预测，表明相对小脑大小没有一致的性别差异。结论：这项工作表明，相对小脑大小的性别差异可能受到发育限制或缺乏一致的选择压力的影响，并强调需要更多个体水平的灵长类动物神经解剖学数据，以促进大脑的特异性内和特异性研究性别二态。
大脑行为进化