Department of Anatomy, Midwestern University, Glendale, AZ 85308, USA
Department of Anatomical Sciences, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA.
J R Soc Interface. 2018 Aug;15(145). doi: 10.1098/rsif.2018.0205.
Humans are unique among apes and other primates in the musculoskeletal design of their lower back and pelvis. While the last common ancestor of the lineages has long been thought to be 'African ape-like', including in its lower back and ilia design, recent descriptions of early hominin and Miocene ape fossils have led to the proposal that its lower back and ilia were more similar to those of some Old World monkeys, such as macaques. Here, we compared three-dimensional kinematics of the pelvis and hind/lower limbs of bipedal macaques, chimpanzees and humans walking at similar dimensionless speeds to test the effects of lower back and ilia design on gait. Our results indicate that locomotor kinematics of bipedal macaques and chimpanzees are remarkably similar, with both species exhibiting greater pelvis motion and more flexed, abducted hind limbs than humans during walking. Some differences between macaques and chimpanzees in pelvis tilt and hip abduction were noted, but they were small in magnitude; larger differences were observed in ankle flexion. Our results suggest that if and diverged from a common ancestor whose lower back and ilia were either 'African ape-like' or more 'Old World monkey-like', at its origin, the hominin walking stride likely involved distinct (i.e. non-human-like) pelvis motion on flexed, abducted hind limbs.
人类在其腰背和骨盆的骨骼肌肉设计上与猿类和其他灵长类动物有明显的不同。虽然长期以来，人们一直认为该谱系的最后一个共同祖先（包括其腰背和髂骨设计）“类非洲猿”，但最近对早期人属和中新世猿类化石的描述表明，其腰背和髂骨与一些旧世界猴类（如猕猴）更为相似。在这里，我们比较了三种双足猕猴、黑猩猩和人类在相似无因次速度下行走时的骨盆和后肢/下肢的三维运动学，以测试腰背和髂骨设计对步态的影响。我们的研究结果表明，双足猕猴和黑猩猩的运动学非常相似，与人类相比，这两种物种在行走时骨盆运动幅度更大，后肢更弯曲、外展。虽然在骨盆倾斜和髋关节外展方面，猕猴和黑猩猩之间存在一些差异，但这些差异的幅度很小；在踝关节弯曲方面观察到了更大的差异。我们的研究结果表明，如果人类和起源于一个腰背和髂骨要么“类非洲猿”，要么“更类旧世界猴”的共同祖先，那么在起源时，人类的行走步幅可能涉及到弯曲、外展的后肢的独特（即非人类样）骨盆运动。
