CNRS, UMR 7194, Département de Préhistoire du Muséum National d'Histoire Naturelle, Musée de l'Homme, 17 Place du Trocadéro, 75016 Paris, France.
J Hum Evol. 2011 Oct;61(4):488-502. doi: 10.1016/j.jhevol.2011.07.002. Epub 2011 Aug 19.
The occipital bone is frequently investigated in paleoanthropological studies because it has several features that help to differentiate various fossil hominin species. Among these features is the separation between inion and endinion, which has been proposed to be an autapomorphic trait in (Asian) Homo erectus. Methodologies are developed here to quantify for the first time the location of these anatomical points, and to interpret their variation due to the complex interactions between exocranial and endocranial size and shape of the occipital and nuchal planes, as well as the occipital lobes and cerebellum. On the basis of our analysis, neither 'the separation between inion and endinion' nor 'endinion below inion' can be considered as an autapomorphic trait in H. erectus, since this feature is a condition shared by extant African great apes and fossil hominins. Moreover, our results show that the exo- and endocranial anatomy of the occipital bone differs between hominins (except Paranthropus boisei specimens and KNM-ER 1805) and great apes. For example, chimpanzees and bonobos are characterized by a very high position of inion and their occipital bone shows an antero-posterior compression. However, these features are partly correlated with their small size when compared with hominins. Asian H. erectus specimens have a thick occipital torus, but do not differ from other robust specimens, neither in this feature nor in the analysed exo- and endocranial proportions of the occipital bone. Finally, the apparent brain size reduction during the Late Pleistocene and variation between the sexes in anatomically modern humans (AMH) reflect that specimens with smaller brains have a relatively larger posterior height of the cerebellum. However, this trend is not the sole explanation for the 'vertical shift' of endinion above inion that appears occasionally and exclusively in AMH.
枕骨在古人类学研究中经常被研究，因为它有几个特征可以帮助区分不同的化石人类物种。这些特征之一是枕外隆凸和枕内隆凸之间的分离，这被认为是（亚洲）直立人特有的特征。本文方法首次对这些解剖点的位置进行了量化，并解释了由于枕骨和枕骨平面的外颅和内颅大小和形状以及枕叶和小脑之间的复杂相互作用，导致这些解剖点位置发生变化的原因。根据我们的分析，“枕外隆凸和枕内隆凸之间的分离”和“枕内隆凸低于枕外隆凸”都不能被认为是直立人特有的特征，因为这一特征是现存非洲大猿和化石人类共有的特征。此外，我们的结果表明，人类（除了粗壮南方古猿和 KNM-ER 1805 标本）和大猿的枕骨的外颅和内颅解剖结构不同。例如，黑猩猩和倭黑猩猩的枕外隆凸位置非常高，其枕骨呈前后压缩。然而，与人类相比，这些特征部分与它们的小体型有关。亚洲直立人标本具有很厚的枕骨结节，但在这个特征上与其他粗壮标本没有区别，也与枕骨的外颅和内颅比例无关。最后，晚更新世期间大脑尺寸的明显缩小以及在解剖学上现代人类（AMH）中存在的性别差异，反映了大脑较小的标本具有相对较大的小脑后高。然而，这种趋势并不是枕骨结节在 AMH 中偶尔出现且仅出现在 AMH 中的“垂直移位”的唯一解释。
