Rosen Kyle H, Jones Caroline E, DeSilva Jeremy M
Department of Anthropology, Dartmouth College, 6047 Silsby Hall, Hanover, NH, USA.
Department of Psychology, University of Georgia, 125 Baldwin Street, Athens, GA, USA.
Evol Hum Sci. 2022 Mar 14;4:e12. doi: 10.1017/ehs.2022.9. eCollection 2022.
Bipedal locomotion is a hallmark of being human. Yet the body form from which bipedalism evolved remains unclear. Specifically, the positional behaviour (i.e. orthograde vs. pronograde) and the length of the lumbar spine (i.e. long and mobile vs. short and stiff) of the last common ancestor (LCA) of the African great apes and humans require further investigation. While fossil evidence would be the most conclusive, the paucity of hominid fossils from 5-10 million years ago makes this field of research challenging. In their absence, extant primate anatomy and behaviour may offer some insight into the ancestral body form from which bipedalism could most easily evolve. Here, we quantify the frequency of bipedalism in a large sample ( 496) of zoo-housed hominoids and cercopithecines. Our results show that while each studied species of ape and monkey can move bipedally, hylobatids are significantly more bipedal and engage in bipedal locomotion more frequently and for greater distances than any other primate sampled. These data support hypotheses of an orthograde, long-backed and arboreal LCA, which is consistent with hominoid fossils from the middle-to-late Miocene. If true, knuckle-walking evolved in parallel in and , and the human body form, particularly the long lower back and orthograde posture, is conserved.
两足行走是人类的一个标志。然而，两足行走所演化而来的身体形态仍不明确。具体而言，非洲大型猿类和人类的最后共同祖先（LCA）的姿势行为（即直立型与俯伏型）以及腰椎长度（即长且灵活与短且僵硬）需要进一步研究。虽然化石证据将是最具决定性的，但500万至1000万年前人类化石的稀缺使得这一研究领域具有挑战性。在缺乏化石的情况下，现存灵长类动物的解剖结构和行为可能会为两足行走最容易从中演化而来的祖先身体形态提供一些见解。在这里，我们对大量圈养的类人猿和猕猴样本（496个）中的两足行走频率进行了量化。我们的结果表明，虽然所研究的每种猿类和猴类都能两足行走，但长臂猿比其他任何采样的灵长类动物都更显著地经常两足行走，且两足行走的频率更高、距离更远。这些数据支持了关于直立型、长背且树栖的最后共同祖先的假说，这与中新世中晚期的类人猿化石一致。如果这是真的，指关节行走在猩猩和大猩猩中是平行演化的，并且人类的身体形态，特别是长的下背部和直立姿势，是保守的。
