New Human Ancestor Discovered Near Fossil of “Lucy”

The Australopithecine lived about 3.4 million years ago in what is now Ethiopia, around the same time as

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The holotype upper jaw of (BRT-VP-3/1) found on March 4, 2011.

Welcome, Lucy's neighbour. Fossilized jaws and teeth found in northern Ethiopia belong to an ancient human ancestor that researchers say lived around the same time as Lucy's kind,, but is a distinct species. The remains of the new species, which has been dubbed  and lived between 3.5 million and 3.3 million years ago, were uncovered just 35 kilometres from the Hadar site . Fossils from  date to between 3.7 and 3 million years ago, so the two species would have overlapped (though Lucy herself may have lived too recently to see one).

The find suggests that several distinct hominins—species more closely related to humans than to chimps—roamed eastern Africa more than 3 million years ago. A third species, , lived in what is now Kenya around the same time. “The question that is going to come up is which taxa gave rise to our genus, ,” says Yohannes Haille-Selassie, a palaeoanthropologist at the Cleveland Museum of Natural History in Ohio, whose team reports its discovery in . “That’s going to be the 64-million-dollar question.”

Odd one out

Given the close proximity of Hadar, which has yielded hundreds of fossils belonging to , including Lucy’s relatively complete remains, the team guessed that the bones belonged to that species. But closer inspection revealed that the lower jaw was beefier, and the teeth smaller,  than those of the hominin's Hadar neighbours. Neither did  —defined by a flat-faced 3.5-million-year-old skull found near Lake Turkana, Kenya—prove a compelling match.

“We’re convinced this is different from all the species we know,” says Haille-Selassie. To make an even stronger case, his team hopes to link the jawbones to  that his team also found in Woranso-Mille, which belonged to a creature that spent more time in the trees than Lucy’s kind. “Then we’ll be in a better position to say this is a totally new species,” says Haille-Selassie. The species name  derives from words in the local Afar language meaning ‘close’ and ‘relative’.

Haille-Selassie says it is unsurprising that several hominins lived in East Africa some 3.5 million years ago; their descendants were similarly diverse one million years later.

Fred Spoor, a palaeontologist at University College London who wrote an accompanying News and Views article on the study, speculates that the two species may both have been able to thrive side-by-side because they might not have directly competed for food, shelter and territory. The distinct jaw shapes of and  could mean that they used their teeth on different kinds of food. But with so little evidence to hand, Spoor warns against jumping to conclusions about the relationship between the two species. "We shouldn’t suddenly think they stood at the Awash River, shook hands and said, ‘What are you doing here?’”

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