An international team claims to have identified the extinct "hominin" (human like creature) as the first human cousin from a DNA sample -- extracted from a bone fragment of a little finger found two years ago in a Siberian cave. In fact, the scientists have sequenced the genetic material from the fossil of the creature, nicknamed "X-woman", to show that it is very distinct from that of Neanderthals and modern humans.
Professor Chris Stringer, human origins researcher at London's Natural History Museum, called the discovery "a very exciting development". "This new DNA work provides an entirely new way of looking at the still poorly understood evolution of humans in central and east Asia. It looks like nature was experimenting in how to be human, and we're the last survivors," the British media quoted Stringer as saying.
The discovery also raises the intriguing possibility that three forms of human - Homo sapiens, Neanderthals and the species represented by X-woman - could have met each other and interacted in southern Siberia, say the scientists.
In fact, the tiny fragment of bone from a fifth finger, dated to between 48,000 and 30,000 years old, was uncovered by archaeologists working at the Denisova Cave in Siberia's Altai Mountains in 2008, where modern humans and Neanderthals are known to have lived at the same time.
The latest analysis carried out by the team, led by Johannes Krause from the Max Planck Institute for Evolutionary Anthropology in Germany, revealed the human from Denisova last shared a common ancestor with modern humans and Neanderthals about one million years ago. This is known as the divergence date; essentially, when this human's ancestors split away from the line that eventually led to Neanderthals and ourselves.
The Neanderthal and modern human evolutionary lines diverged much later, around 500,000 years ago. This shows that the individual from Denisova is representative of a previously unknown human lineage that actually derives from an hiterto unrecognised migration out of Africa.
"Whoever carried this mitochondrial genome out of Africa about a million years ago is some new creature that has not been on our radar screens so far," said co-author Professor Svante Paabo, also from the Max Planck Institute for Evolutionary Anthropology.
The new creature probably left Africa soon after the date of its last shared ancestor with humans and Neanderthals, about a million years ago, suggest the findings published in the 'Nature' journal.
