Laboratory of Ecology, Evolution and Biodiversity Conservation, Katholieke Universiteit Leuven, Charles Deberiotstraat 32 Bus 2439, 3000 Leuven, Belgium; Department of African Zoology, Royal Museum for Central Africa, Leuvensesteenweg 13, 3080 Tervuren, Belgium.
Department of African Zoology, Royal Museum for Central Africa, Leuvensesteenweg 13, 3080 Tervuren, Belgium; Laboratory of Histology and Neuropathology, Université Libre de Bruxelles, CP620 - Route de Lennik 808, 1070 Brussels, Belgium.
J Hum Evol. 2023 Nov;184:103439. doi: 10.1016/j.jhevol.2023.103439. Epub 2023 Oct 5.
Sexual dimorphism of the nervous system has been reported for a wide range of vertebrates. However, understanding of sexual dimorphism in primate cranial structures and soft tissues, and more particularly the brain, remains limited. In this study, we aimed to investigate the external and internal (i.e., endocast) cranial differences between male and female eastern lowland gorillas (Gorilla beringei graueri). We examined the differences in the size, shape, and disparity with the aim to compare how sexual dimorphism can impact these two structures distinctively, with a particular focus on the endocranium. To do so, we reconstructed gorilla external crania and endocasts from CT scans and used 3D geometric morphometric techniques combined with multivariate analyses to assess the cranial and endocranial differences between the sexes. Our results highlighted sexual dimorphism for the external cranium and endocast with regard to both size and shape. In particular, males display an elongated face accompanied by a pronounced sagittal crest and an elongated endocast along the rostroposterior axis, in contrast to females who are identified by a more rounded brain case and endocast. Males also show a significantly larger external cranium and endocast size than females. In addition, we described important differences for the posterior cranial fossae (i.e., the position of the cerebellum within the brain case) and olfactory bulb between the two sexes. Particularly, our results highlighted that, relatively to males, females have larger posterior cranial fossae, whereas males have been characterized by a larger and rostrally oriented olfactory bulb.
神经系统的性别二态性在广泛的脊椎动物中都有报道。然而，对于灵长类动物颅骨结构和软组织，尤其是大脑的性别二态性的理解仍然有限。在这项研究中，我们旨在研究雄性和雌性东部低地大猩猩（Gorilla beringei graueri）的外部和内部（即内颅骨）颅骨差异。我们检查了大小、形状和差异，目的是比较性别二态性如何能显著影响这两种结构，特别是对内颅骨。为此，我们从 CT 扫描重建了大猩猩的外部颅骨和内颅骨，并使用三维几何形态测量技术结合多元分析来评估性别之间的颅骨和内颅骨差异。我们的结果突出了外部颅骨和内颅骨在大小和形状上的性别二态性。特别是，雄性的面部拉长，伴随着明显的矢状嵴和沿前后轴拉长的内颅骨，而雌性的颅骨和内颅骨则更圆。雄性的外部颅骨和内颅骨尺寸也明显大于雌性。此外，我们还描述了两性之间在后颅窝（即小脑在颅骨内的位置）和嗅球之间的重要差异。特别是，我们的结果强调，相对于雄性，雌性的后颅窝更大，而雄性的嗅球更大，且更靠前。
