There were 3 types of human species 30,000 years ago: study
Scientists have discovered a new mysterious species of human which they believe lived alongside the Neanderthals some 30,000 years ago.
The cavemen, called Denisovans, was identified from DNA taken from a tooth and finger bone found in a cave in Siberia.
Scientists believe that the pre-historic humans roamed the Earth during the last Ice Age when modern humans were developing sophisticated stone tools, jewellery and art.
The finding means there were at least three distinct members of the human family tree alive at the time -- modern humans, Neanderthals and Denisovans, the Daily Mail reported.
Provisional tests on the bones, believed to be of a young girl nicknamed the X-Woman, suggested that she belonged to an entirely new species.
Now, a fully DNA analysis has confirmed her place on the increasingly muddled human family tree.
The little finger belonged to a girl aged around five to seven and was found in the Denisova cave in the Altai Mountains in southern Siberia in 2008 alongside ornaments and jewellery.
The tooth resembles much older human ancestors -- such as Homo erectus -- which died out one million years ago.
According to scientists, the Denisovans were physically different from the thickset Neanderthals and modern humans although they also walked upright two legs.
They lived at a time when our ancestors, and the Neanderthals, were fishing and hunting, wearing jewellery, painting caves and making animal carvings, the researchers said.
The DNA test showed that the tooth and finger bone came from different people, they reported in the journal Nature.
The study found extracts of Denisovan DNA in modern day inhabitants of Melanesia -- the islands to the north and east of Australia which include New Guinea. That suggests the Denisovans interbred with the ancestors of Melanesians and may have been widespread in Asia.
"This is an incredibly well-preserved sample, so it was a joy to work with data this nice," said Dr Richard Green from the University of California, Santa Cruz.
"We don't know all the reasons why, but it is almost miraculous how well-preserved the DNA is," Dr Green said.
The new species appears to have been a "sister group" to the Neanderthals and its discovery paints a complicated picture of human evolution and migration out of Africa -- the cradle of mankind, he said.
Dr Green believes that one group of early human ancestors left Africa between 300,000 and 400,000 years ago and quickly split up.
One branch evolved into the Neanderthals who spread into Europe, while the other moved east and became Denisovans.
Around 70,000 years there was another wave of migration when modern humans quit Africa.
These were our ancestors and they first encountered and interbred with Neanderthals - leaving traces of Neanderthal DNA in the genetic code of all non-Africans alive today.
One group of modern humans later came into contact with Denisovans, leaving traces of Denisovan DNA in the humans who settled in Melanesia, Dr Green said.
"This study fills in some of the details, but we would like to know much more about the Denisovans and their interactions with human populations."
