London, Jan 28 (IANS): In a thrilling work, scientists have successfully sequenced the DNA of a 40,000-year-old Neanderthal found in Siberia without contamination from modern DNA.

This could help scientists finally analyse some of the most intriguing archaic human fossils which have been inaccessible because of contamination from modern DNA, mostly in the lab.

The method appears to work on very contaminated samples as well as on incredibly ancient remains, says research.

“While handling ancient bones, archaeologists often contaminated the archaic DNA sequences with their modern genetic material,” said Pontus Skoglund, a paleogenomics researcher at Uppsala University in Sweden.

The new method “takes us one step closer to being able to use even the most contaminated bones to ask questions about evolution”, Skoglund added.

The new technique takes advantage of the fact that DNA degrades in a predictable way over time, said the study appeared in the journal Proceedings of the National Academy of Sciences.

Based on the differences between the fossil DNA and the modern genome, the team can estimate a sample's degradation level, and in turn, its age.

To test the method, researchers analysed genetic material from a roughly 40,000-year-old Neanderthal found in Okladnikov Cave in Siberia.

The ancient Neanderthal's mitochondrial genome, or DNA that is passed on through the mother and carried in the egg's cytoplasm, was much more closely related to western Neanderthal samples than had previously been found.

“The model works even better on very old DNA because it's more degraded and thus easier to distinguish from modern samples,” added Skoglund.