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Image: Nature Communications, M. Dominguez-RodrigoA pinky bone found in Tanzania has been dated to 1.84 million years. It looks very much like a modern human’s – and is the earliest such indication of modern-like hands capable of using tools, according to a study published in the journal Nature Communications today.

The bone was found by an international team in the Olduvai Gorge, the trove where the Leakeys and others made major discoveries about human ancestors over the last century.

READ MORE: Today in Lab History: Louis Leakey

“The new Olduvai fossil represents the earliest known hominin hand bone with (modern human-like) appearance,” they wrote. “Our results, along with the archaeological record, reveal that instead of following an orderly trend, eventually culminating in the modern human condition, some ‘primitive’ hand bone morphologies persisted side-by-side with (modern human-like) hand bone morphologies well after the first appearance of stone tools and zooarchaeological evidence of their use for butchery by at least (2.6 million years ago).”

The pinky in question is in the midrange of human length, and the upper range of modern gorillas – but is shorter than chimpanzees and monkeys, they said.

The pinky bone indicates less commitment to tree climbing, if any, for our ancestor, they added.

What species the bone belongs to is still undetermined. It’s too old to be Homo sapiens, and could be from Homo erectus or Paranthropus robustus.

But matching skulls are still needed to match individual bones with branches of the family tree – even if the pinky find “indicates that several key aspects of modern human body morphology emerged very early in human evolution,” the authors concluded.

“We are confident that the eventual discovery of more hominin fossils and associated archaeological remains from our ongoing fieldwork at the new Olduvai site… will facilitate the detailed investigation of this issue and also shed even more light on the earliest stages of the evolution of the genus Homo.”

One of the authors of the new study was also part of the team that published a study last month claiming that chimp hands changed more through evolution than their human counterparts’ did over the same time.

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