No expert in armchair palaeontology, though I've read a lot... but doesn't it seem to make more sense that The Ancestral Hominid would have been successful by having approached (or achieved) bipedalism before, rather than during, the climate change?

The relative brevity of a climatic event, as compared to the geological scale usually needed for major evolutionary change, has always made me wonder about the prevailing theory. The latter would have animals stilll built for brachiation "stranded" in the savannah, unable to straighten up and see over the grass, for a very long time - tasty morsels for the felids, pantherids, and whatever other carnivores were about.

Just a thought...

E'