Econintersect: One of the four identified early branches of the human family tree has had a complete genome determined from a small finger bone which belonged to a girl who lived more than 50,000 years ago. The bone, recovered from a cave in Siberia, belonged to a member of the so-called Denisovan branch of the homo sapiens family. This early branch of the human family co-existed with Neanderthals and the branch that led to caucasian, far eastern and melanesian modern humans. Interbreeding between some of these "strains" probably occurred, but evidence has only been found to prove some of the possible alliances actually occurred (discussed below).
The picture is an artist impression of a Denisovan face from an article in HubPages.
Having the complete genome of a Denisovan is remarkable because they have only recently been identified, whereas Neanderthals have been known for almost 200 years. There has yet been sufficient Neanderthal DNA recovered to do the species' genome.
From an article by Ann Gibbons in Wired:
By comparing the genetics of modern humans with relatives in the evolutionary tree, it appears there are more than 100,000 genetic mutations that most people alive today share, but which our closest relatives in the evolutionary line did not have, said Svante Paabo, a biologist at the Max Planck Institute of Evolutionary Anthropology who led the research team.
Some of these genetic changes that are unique to humans have to do with brain function and brain development, Paabo noted.
“This is essentially a ‘genetic recipe’ ” for being a modern human, Paabo said in an e-mail. “Scientists can now start working on understanding how we differed from Denisovans and Neanderthals.”
Little is known about the Denisovans. Although some of their remains were found in southern Siberia, their genetic signature is not present today anywhere apart from islands in the Pacific. About 3% to 5% of the DNA of people from Melanesia (islands in the southwest Pacific Ocean), Australia and New Guinea as well as aboriginal people from the Philippines is from the Denisovans.
It’s only people in those places who have Denisovan DNA, Paabo said, which means the Denisovans must have been in Southeast Asia at one time.
By contrast, everyone who lives outside Africa today probably has some Neanderthal DNA in them, Paabo said in a news briefing Wednesday.
Paabo was reluctant to say Denisovans and Neanderthals were separate “species” but rather called them extinct “groups.”
GEI News reported nearly two years ago on early DNA studies using material from this small finger bone:
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.
Another family tree diagram from Nature shows how a small humanoid species nicknamed "Hobbits" are related. These humanoids disappeared about 10,000 years ago.
- Genome Brings Ancient Girl to Life (Ann Gibbons, Wired, 31 August 2012)
- Fourth "Modern" Humanoid Identified (GEI News, 23 December 2012)