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Genetic material pulled from a pinky finger bone found in a Siberian cave shows a new and unknown type of pre-human lived alongside modern humans and Neanderthals, scientists reported.
The creature, nicknamed "Woman X" for the time being, could have lived as recently as 30 000 years ago and appears only distantly related to modern humans or Neanderthals, the researchers reported.
"It really just looked like something we had never seen before," Johannes Krause of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, said. "It was a sequence that looked something like humans but really quite different."
Writing in Nature, Krause and colleagues said they sequenced DNA from the mitochondria, a part of the cell, which is passed down virtually intact from a woman to her children. They compared it to DNA from humans, Neanderthals and apes. The sequence indicates the hominin's line diverged about a million years ago from the line that gave rise to both humans and Neanderthals and that split about 500 000 years ago.
That makes it younger than Homo erectus, the pre-human that spread out of Africa to much of the world about 1.9 million years ago.
Creature not named as new species yet
"It is some new creature that has not been on our radar screen so far," said Svaante Paabo, a colleague of Krause's who specialises in analysing ancient DNA. And it would have lived near to both modern humans and Neanderthals. "There were at least three ... different forms of humans in this area 40,000 years ago," Paabo said.
Krause and Paabo are careful not to name the creature a new species just yet. They are now working to sequence nuclear DNA -- the DNA that makes up most of the genetic code, which will tell a great deal more about "Woman X".
The genetic sequence tells scientists little about what the creature would have looked like or whether it interacted with other humans living in the Altai mountains of Siberia, where the pinky finger bone was found.
The work, done using a DNA sequencer made by Illumina Ltd, suggests a new way is opening to identify the ancestors of humanity. Krause and Paabo had only a tiny fragment of bone to work with and cannot reconstruct a skeleton in the time-honored manner of most paleontologists.
But there may be more there. The cold, dry conditions of the Altai mountains preserve the DNA. Stone tools also have been found in the area, as well as the bones of woolly mammoths but only tantalising fragments of human bone and teeth.
Researchers have sequenced DNA from mammoths frozen in Siberia and the same team has sequenced DNA from Neanderthals.
Paabo and Krause said it is theoretically possible the creature is related to another potential third species of human -- Homo floresiensis, nicknamed "hobbit" -- which lived on an island in modern-day Indonesia about 17 000 years ago.
The team has tried without success to get DNA from hobbit bones. Most skeletons of pre-humans have been found in warm places such as Africa, but hot, wet conditions break down DNA. - (Reuters Health, March 2010)
