Ethiopian bone-anza buttresses human family tree

Awash with hominids

Paleontologists have unearthed an unprecedented cache of early human fossils in Ethiopia. The discoveries, reported in Nature, bone-up the story of our ancestors in the cradle of humanity.

The remains belong to hominids – the collective term for humans and human-like apes – of the genus Australopithecus, a forerunner to our own, Homo. The international team toiled for five years alongside local people in the Middle Awash Valley, which lies in the Afar region. The finds, from at least nine individuals, are mostly teeth but include jaw, hand and thighbones.

The hominid material had to be distinguished from monkeys and other mammals; our ancestors in the Middle Awash led a woodland lifestyle. Their brains were around the same size as modern chimps'.

The most famous fossil in the world, “Lucy”, is an Australopithecus that lived in Ethiopia over three million years ago. Modern humans by comparison are a newbie on the hominid scene, having first stepped out about 150,000 years ago.

At more than four million years old, the new fossils are even older than Lucy. They fill in a gap between Australopithecus and one of the candidates for their own even more ape-like ancestors, Ardipithecus.

The origin of Australopithecus is one of the key questions in the descent of man; it seems there was a profusion of ambitious apemen in East Africa at the time.

Research co-director Dr Berhane Asfaw said: “For the first time, we found fossils that allow us to connect the first phase of human evolution and the second phase”

The particular species of Australopithecus they found, anamensis is not new to science. It is new to the Middle Awash however, and so fills in another page in the story, throwing weight behind Ardipithecus' claim on human ancestry.

It either evolved from Ardipithecus on the spot, or evolved in one of the other areas where its bones have been found, and invaded the region. Either way, the region was the first skirmish of the evolutionary melee which Homo sapiens eventually emerged victorious from.

The scientists say the shift from Ardipithecus to Australopithecus seems relatively rapid in evolutionary terms. The key differences were the development of a robust jaw for crunching tough but nutritious roots, and possibly the first emergence of upright walking.

At a press conference in Ethiopia Asfaw took the opportunity to use the finds for a dig at creationists: “We have proved that one [species] is transforming into the other, so this evidence is important to show that there is human evolution. Human evolution is a fact and not a hypothesis.”

Work continues in the region.®

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