Meet Digit, the new type of human

NICKY PHILLIPS
March 25, 2010 - 6:10AM

THE human family has a new member.

A previously unknown type of ancient human, who lived about 40,000 years ago, has been identified using DNA from a finger bone found in Siberia.

The extraordinary find brings to four the number of human species thought to have roamed the earth at that time.

Six years ago only two were known: Neanderthals and modern humans. Then, in 2004, scientists announced the discovery of a hobbit-sized species of extinct human on the Indonesian island of Flores.

"Forty thousand years ago, the planet was more crowded than we thought," said Terence Brown, of the University of Manchester.

A team led by Johannes Krause, of the Max Planck Institute in Germany, discovered the finger – thought to be a "pinky" – in a cave in the Altai Mountains of southern Siberia. Dr Krause said the DNA it contained was different to that of both Neanderthals and modern humans.

He carried out extensive testing to confirm the mitochondrial DNA, passed from mothers to their offspring, was authentic and had not been contaminated by DNA from other sources.

"[It] was from what seemed to be a new hominin lineage," said Dr Krause, whose findings are published in the journal Nature.

Dr Krause was so shocked he called his colleague Svante Paabo – who sequenced the DNA of Neanderthals last year – to tell him about the find.

"At first I didn't really believe him, I thought he was pulling my leg," said Professor Paabo.

This is the first time a new human ancestor has been identified by its DNA sequence rather than from the study of its bones.

With only DNA evidence to go by, the researchers have said it is impossible to tell what the species would have looked like. And although they could not determine the sex of the individual to whom the finger belonged, the researchers have nicknamed the prehistoric person "X-woman".

The first human group to leave Africa, about 2 million years ago, was Homo erectus. They were followed by Neanderthals around 500,000 years ago, and modern humans around 50,000 years ago.

Professor Paabo said the x-woman type of human would have developed much later than Homo erectus but long before Neanderthals. Modern humans shared a common ancestor with the unknown hominin about a million years ago, he said.

The X-woman humans seem to have lived alongside Neanderthals and modern humans.

http://www.smh.com.au/world/science/meet-digit-the-new-type-of-human-20100325-qx2i.html
(Submitted by Paul Cropper)