Scientists have identified the missing part of a finger bone fragment from the Denisova Cave in southern Siberia, revealing that Denisovans - an early human population discovered when the original fragment was genetically sequenced in 2010--had fingers indistinguishable from modern humans despite being more closely related to Neanderthals.
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| The two fragments of Denisova 3's fingertip, reunited in digital form [Credit: Bennett et al. 2019] |
The Denisovans lived in Asia for hundreds of thousands of years, sometimes interbreeding with Neanderthals and perhaps archaic Eurasian humans, with some present-day human populations still carrying Denisovan DNA.
However, only five Denisovan skeletal remains have been found--mostly molars--and the finger bone fragment previously recovered and used to generate the genome was too incomplete to reveal much about the whole appendage.
E. Andrew Bennett et al. matched the missing fragment to the original by using DNA extraction and sequencing techniques to capture its entire mitochondrial DNA sequence.
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| Side-by-side comparison of Denisova 3's digitally reconstructed finger (right) with the same bone from a recent human (center) and a Neanderthal (left). Notice how wide the tuft (fingertip, toward the top of the image) is on the Neanderthal bone compared with the other two [Credit: Bennett et al. 2019] |
They then reanalyzed scans and photographs of the fragments and compared them with finger bones from Neanderthals, as well as Pleistocene and recent modern humans at various stages of development.
The researchers found that the digit was a fifth finger bone from the right hand of an adolescent female Denisovan who likely died at about 13.5 years old.
The authors say researchers should take caution when identifying potential Denisovan skeletal remains, since they may appear more similar to modern humans than to Neanderthals.
The findings are published in Science Advances.
Source: American Association for the Advancement of Science [September 04, 2019]
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