Thorpe S K S, Holder R L, Crompton R H
School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Science. 2007 Jun 1;316(5829):1328-31. doi: 10.1126/science.1140799.
Human bipedalism is commonly thought to have evolved from a quadrupedal terrestrial precursor, yet some recent paleontological evidence suggests that adaptations for bipedalism arose in an arboreal context. However, the adaptive benefit of arboreal bipedalism has been unknown. Here we show that it allows the most arboreal great ape, the orangutan, to access supports too flexible to be negotiated otherwise. Orangutans react to branch flexibility like humans running on springy tracks, by increasing knee and hip extension, whereas all other primatesdothe reverse. Human bipedalism is thus less an innovation than an exploitation of a locomotor behavior retained from the common great ape ancestor.
人类两足行走通常被认为是从四足陆地祖先进化而来的，但最近一些古生物学证据表明，两足行走的适应性特征是在树栖环境中出现的。然而，树栖两足行走的适应性益处一直不为人知。在此我们表明，它能让最擅长树栖的大型猿类——红毛猩猩——利用那些过于灵活而无法以其他方式通过的支撑物。红毛猩猩对树枝灵活性的反应就像人类在有弹性的跑道上奔跑一样，通过增加膝盖和臀部的伸展，而所有其他灵长类动物则相反。因此，人类两足行走与其说是一种创新，不如说是对从共同的大型猿类祖先那里保留下来的一种运动行为的利用。
