Experts from the US and Russia said they had pieced together 80 per cent of the mammoth genome, using DNA samples extracted from hair preserved over tens of thousands of years

The chemical sequences shed new light on the evolution of mammoths and elephants and are expected to help answer why the extinct animals failed to survive.

They may also help future researchers bring the mammoth back to life by inserting its genes into the modern day elephant, the scientists believe.

However, other experts stressed that resurrecting the woolly mammoth would be an enormously difficult task.

Much of the work was done using DNA taken from hair from two mammoths mummified in Siberian permafrost. One had been buried for 20,000 years and the other for at least 60,000. DNA data from a number of other specimens investigated previously helped to complete the genetic jigsaw.

Hair was a better source of DNA than bone because it protected the strands of genetic material like "biological plastic", said the scientists.

The findings, reported today in the journal Nature, revealed that woolly mammoths and modern day elephants share many genes and are more closely related than had previously been thought.

The mammoth genome differs from that of the African elephant by as little as 0.6% - about half the difference between humans and chimpanzees.

Analysis of the DNA sequences showed that woolly mammoths separated into two groups around two million years ago.

These eventually became genetically distinct sub-populations. One went extinct about 45,000 years ago, while the other lived on until after the last ice age, around 10,000 years ago. Mammoths and modern elephants took separate evolutionary paths some six million years ago.