Great apes and humans evolved from a long-backed ancestor
Great apes and humans evolved from a long-backed ancestor
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DOI：
10.1016/j.jhevol.2020.102791
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发表时间：
2020-07-01
影响因子：
3.2
通讯作者：
Reno, Philip L.
中科院分区：
文献类型：
--
作者：
Machnicki, Allison L.;Reno, Philip L.
目前的争论是，人/泛最后的共同祖先（LCA）是否像类人猿一样有一个短而僵硬的腰柱，或者在广义的中新世人科动物中观察到一个更长而灵活的腰柱。除了只有四个节段之外，还有三个额外的特征有助于腰椎硬化：过渡椎（TV）的位置、腰椎棘突的方向和腰椎在髂骨片之间的卡压。对于类人猿来说，这些特征如果从短背LCA遗传而来，则是同源的，但如果从长背LCA进化而来，则可能通过不同的表型在功能上趋同。我们定量和定性分析人类，猿，猴胸椎和腰椎使用三维表面扫描和骨质测量比较棘突形态和骶骨深度。我们还使用了一个大样本的古猿脊椎计数，以评估在电视和腰骶边界的位置变化。所有现存的类人猿都把电视放在最后的胸部。然而，人类和猩猩把电视放在第19个颅后椎骨节，而其他猿类把电视放在第20个。此外，黑猩猩、大猩猩和红毛猩猩都有不同的棘突成角模式和与腰椎变硬相关的形态，而人类棘突形态与长背长臂猿、猴子和中新世原始人Morotopithecus和Pierolapithecus相似。最后，黑猩猩与其他人科动物相比是独特的，具有更大的骶骨深度，有利于腰椎卡压，非洲猿之间存在差异，腰骶边界的变化机制。这些差异表明，腰椎硬化是收敛在类人猿和人类两足动物进化从一个更普遍的长背祖先。这样的模型与南方古猿中电视放置的证据更加一致。(C)2020爱思唯尔有限公司保留所有权利。
There is current debate whether the Homo/Pan last common ancestor (LCA) had a short, stiff lumbar column like great apes or a longer, flexible column observed in generalized Miocene hominoids. Beyond having only four segments, three additional features contribute to lumbar stiffening: the position of the transitional vertebra (TV), orientation of the lumbar spinous processes, and entrapment of lumbar vertebrae between the iliac blades. For great apes, these features would be homologous if inherited from a short-backed LCA but likely functionally convergent through dissimilar phenotypes if evolved from a long-backed LCA. We quantitatively and qualitatively analyzed human, ape, and monkey thoracic and lumbar vertebrae using 3D surface scanning and osteological measurements to compare spinous process morphology and sacral depth. We also used a large sample of hominoid vertebral counts to assess variation in the position of the TV and lumbosacral boundary. All extant hominoids modally place the TV at the ultimate thoracic. However, humans and orangutans place the TV at the 19th postcranial vertebral segment, whereas other apes place the TV at the 20th. Furthermore, chimpanzees, gorillas, and orangutans each have distinct patterns of spinous process angulation and morphology associated with lumbar stiffening, while human spinous process morphology is similar to that of longer backed gibbons, monkeys, and Miocene hominoids Morotopithecus and Pierolapithecus. Finally, chimpanzees are unique compared with other hominoids with a greater sacral depth facilitating lumbar entrapment, and there are differences among African apes with respect to the mechanisms governing variation in the lumbosacral boundary. These differences suggest that lumbar stiffening is convergent among great apes and that human bipedalism evolved from a more generalized long-backed ancestor. Such a model is more consistent with evidence of TV placement in Australopithecus. (C) 2020 Elsevier Ltd. All rights reserved.