Question

I'd like you to first explain to me what Lieberman proposes our common ancestor with chimpanzees (LCA) would look/behave like. Please explain his reasoning and what fossil evidence there is to support it. (150 wds)

Answer 1

The nature of LCA (Last common ancestor) from which bI pedals evolved are question of debate, here lieberman suggest that the presence of do not have a stiff lateral midfoot and instead both possess a highly mobile tarsometatarsal joint during a midtarsal break and which could be a primitive character for bipedal's in terrestrial habitats. The ardepethicus found to have simila anotomical features intermediate to chimpanzee and human.

Hence chimpanzees are considered as better modal for LCA for Pan homo and they face little change after splitting from bonbons, but bonbons subjected lot of changes. The human genome has lot of similarity with chimpanzees. All these suggest the possibility of LCA more like chimpanzee than others.

The bypedalism with no well-defined plantar aponeurosis in orangutans, potentially gibbons, colobines, and platyrrhines, suggests that a human-like organization of the plantar aponeurosis evolved convergently in cercopithecines and African apes, likely as an adaptation to terrestrial locomotion. This scenario supports the argument that the LCA of humans and chimpanzees frequently engaged in terrestrial quadrupedalism. Since the early homonins diverged from chimpanzees early to the LCA for example sahalopethicus and ardepethicus they retained more ape like characters.