Homo naledi shows more of its hand

CAPE TOWN — Scientists yesterday released more details about the hands and feet of Homo naledi, a new species of human relative discovered in the Cradle of Humankind.

While the two research papers published in Nature Communications do not change the story thus far, namely that Homo naledi had unique characteristics that enabled it to walk on two legs and climb trees, they provide important new details to fellow scientists.

The discovery of Homo naledi was announced last month by a University of the Witwatersrand research team whose claim that Homo naledi is a new species has been met with scepticism by some scientists. But no one disputes the scientists have unearthed a haul of fossils on an unprecedented scale.

The fossils retrieved to date belonged to a slender, long-legged creature with a brain that was about the size of an orange, or a third the size of ours. It had a unique mix of primitive ape-like features — such as broad shoulders and ribs — and modern human-like ones such as small teeth. Its hands had broad thumbs and curved fingers, features that made them good for making tools and climbing trees.

Its feet looked remarkably like those of humans.

“Even though the foot is quite modern, we don’t think this creature walked like modern humans because the rest of its body is different,” said Bernhard Zipfel, senior collections curator at the Evolutionary Studies Institute at Wits University and lead author of the study detailing a nearly complete adult Homo naledi foot. Its hips for example, were more like those of the more primitive Australopithecus africanus, or Au afarensis, he said.

Its long legs suggested it could walk long distances, but its primitive hips indicated it was far from being an endurance runner, he said.

Homo naledi offered insight into the debate about how and when we began to walk upright, suggesting the feet evolved before the brain started becoming bigger, rather than the other way around, he said.

The features of the hand and its brain size had implications for what cognitive requirements might be required to make and use tools, said Tracy Kivell, of the University of Kent and lead author of the paper describing the hand.