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Humanity鈥檚 ancient family tree is set to be shaken up by fossil skeletons found embedded in rock at a site near Johannesburg, South Africa. They could be from another long lost human cousin.聽鈥淲e have another major hominin discovery,鈥� said Lee Berger聽at 麻豆传媒 Live on Saturday.

In the past decade,聽 Berger at the University of the Witwatersrand in South Africa and his team has discovered not one but two new species of human ancestor.

In 2010, Berger made the headlines when he (or rather, his then 9-year-old son) discovered the remains of a new species of human in the hills north of Johannesburg. This was聽Australopithecus sediba, which lived around 2 million years ago and appears to be our closest ape-like ancestor.

Then, in 2013, Berger hit the fossil jackpot again, with the remarkable discovery of thousands of bones deep inside the Rising Star cave system also near Johannesburg. These turned out to belong to a new species of tiny, small-brained hominin called聽Homo naledi. This fossil hominin is transforming our understanding of human evolution, not least because聽H. naledi聽lived very recently,聽around 250,000 years ago, and has a strange mix of modern and archaic features.

But Berger is on a roll. The new fossil hominin remains he has discovered are located near the Rising Star caves, but the bones haven鈥檛 yet been excavated due to the challenging nature of their location. 鈥淚t鈥檚 a difficult site,鈥� said Berger, as the fossils are embedded in very hard rock.

So could this be another new species? 鈥淚 don鈥檛 know.聽We haven鈥檛 got them out of the rock yet,鈥� said Berger. 鈥淎ll I have is a glimpse of several individuals and that they are not very tiny.鈥� The large size of the jaw and teeth means that the skeletons don鈥檛 belong to the diminutive聽H. naledi, and they are not聽A. sebida聽either, he said.

One possibility is that they are another species of the ape-like Australopithecus. Another is that they are an entirely new species. Fossil remains of our ancient cousins are exceedingly rare, so either way, these bones will shed new light on our deep family tree.

Buried treasure

But this is just one of many new sites with remains of hominins 鈥渒nown or unknown鈥� awaiting excavation that Berger and his team have discovered. 鈥淲e have a multitude of early hominin discoveries at different sites,鈥� he said. 鈥淣ow we鈥檙e in this period where it鈥檚 exploding, where we鈥檙e finding that these things are not as rare as we thought. We were often just looking in the wrong place or with the wrong eyes.鈥�

While we wait for these bone treasure troves to be excavated we can expect new insights into聽H. naledi聽too. Although the first attempts to extract DNA from the skeletons didn鈥檛 succeed, studies are ongoing and will hopefully reveal where this species fits on the hominin family tree. 鈥淢olecular studies are in play,鈥� said Berger.

Early next year we can also expect a study which reveals a relationship between聽H. naledi聽and another species, says Berger. 鈥淭hat will be big news,鈥� he said. 鈥淭hese are exciting times.鈥�