BBC: A fourth primary type of modern humanoid, known as the "Denisovans", has been identified and DNA testing indicates that they interbred with another branch more closely related to present day Eurasians. These DNA traces are found in the some of the Australian aboriginal people, but no where else so far.
The ancient humans have been dubbed Denisovans after the caves in Siberia where their remains were found. There is also evidence that this group was widespread in Eurasia.
A study in Nature journal shows that Denisovans co-existed with Neanderthals and interbred with our species - perhaps around 50,000 years ago. An international group of researchers sequenced a complete genome from one of the ancient hominins (human-like creatures), based on nuclear DNA extracted from a finger bone.
The finding adds weight to the theory that a different kind of human could have existed in Eurasia at the same time as our species.
Researchers have had enigmatic fossil evidence to support this view but now they have some firm evidence from the genetic study carried out by Professor Svante Paabo of the Max Planck Institute in Leipzig, Germany. "A species of early human living in Europe evolved," according to Professor Paabo. "There was a western form that was the Neanderthal and an eastern form, the Denisovans."
The study shows that Denisovans interbred with the ancestors of the present day people of the Melanesian region north and north-east of Australia. Melanesian DNA comprises between 4% and 6% Denisovan DNA.
It is believed that some archaic precursor evolved into two distinct hominin groups that evenually led to two groups of homo sapiens which are primarily distinguished genetically in that one goup interbred with Neanderthals (the Eurasian group) and one group (African) did not. Read more.....
Hat tip to Naked Capitalism.