One explanation (other than a misinterpretation of the anatomy) is that the chimp-human split is earlier than has recently been thought. There is good evidence for this. That maybe easier to believe than that gorill-chimp body plans evolved twice.

Another explanation is that there was a greater diversity of hominoids than previously thought (not a suprise) and that among them there was a greater diversity of locomotory patterns.

Along with this last bit, one can note that the difference in the overall anatomy of an early asutralopith and a modern chimp is very modest except in a few areas. The “human like” walking of early austrlopiths pushed by White, Lovejoy and Leakey is believed by a limited range of anatomists and is predicted, frankly, by where one works, what permits are needed, funding sources, (i.e. the usual tribal factors) more than by the measurements of the bones.

I’m not at all interested in closing off the possibility that the LCA was more human like in locomotion that otherwise thought. I am, in fact, one of those people who suggested this at great risk to myself at conferences, etc., years back. I’m just not convinced of two things: a) That this evidence is being interpreted right and b) that a semi-bipedal positional behavior is all that important in an earl hominoid.

Thomersons came from England. Why are there still Thomersons in England?