London, June 10 : By sequencing five new complete genomes of mitochondrial DNA (mtDNA) of woolly mammoths, an international team of scientists has determined that the now extinct animal existed as two groups 40,000 years ago, originating from a common ancestor.
According to a report in Nature News, Thomas Gilbert at the University of Copenhagen in Denmark led the team.
Gilbert and his team subjected five hair samples to a new technique that allows entire mtDNA genomes to be sequenced from a single piece of hair.
His haul, when added to 13 previously-sequenced samples provided enough distinct samples to show that the woolly mammoth existed as two groups, or clades, originating from a common ancestor.
The two clades lived in the same place at the same time - although the mammoths from one clade stuck to one small area, and died off much sooner than their relations in the other clade.
Gilbert and his co-workers found that the mtDNA sequences were obviously different between the two clades.
They then looked at the geographical locations of the different beasts, and used carbon dating methods to deduce when the animals lived.
"You can see that you get both groups in the same place at the same time," said Gilbert.
But the two groups had quite different tendencies to roam.
According to Gilbert, one group was quite geographically limited as it stayed in the middle of the high Arctic, whereas the other group wandered much farther afield.
Carbon dating shows that mammoths in the group with the limited range became extinct around 40,000 years ago, whereas the wider-ranging mammoths were still wandering the same areas until around 10,000 years ago.
"The work shows the usefulness of the technique to get genetic information from hair - previously thought to be a very poor source of DNA," said Adrian Lister, from the Natural History Museum in London, UK.