Not Out of the Trees?

The Independent has a story about research indicating that our earliest human precursors might not have been as arboreal as originally thought. Michael McCarthy writes:

Humanity's immediate predecessors may have had trouble climbing trees, research suggests – so they may not have been as ape
-like as many experts believe.

Scientists have arrived at this conclusion after making a close study of the way chimpanzees scale trees – virtually vertically and with ease – and then comparing chimpanzee ankle joints with those of hominins, humans' ancestors.

The hominins lived between 1.5 and 4.1 million years ago, a relatively short time after proto-humans and chimpanzees split from a common ancestor (generally thought to have been between four and eight million years ago). Many experts have argued that this ancestor was probably quite chimpanzee-like, and as a result it has been widely assumed that the earliest humans were ape-like, too.

Given what we know about the bipedalism of Ardipithecus and Australopithecus afarensis, this doesn't seem to me to be too much of a surprise. It is quite possible that bipedality evolved due to selective pressures for a more terrestrial lifestyle, perhaps because they were being out competed by the precursors of modern chimpanzees.

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