By Helen Briggs

BBC News science reporter



Mammoths became extinct in the last few thousand years

The 5,000 DNA letters spell out a large chunk of the genetic code of its mitochondria, the structures in the cell that generate energy.

The research, published in the online edition of Nature, gives an insight into the elephant family tree.

It shows that the mammoth was most closely related to the Asian rather than the African elephant.

The three groups split from a common ancestor about six million years ago, with Asian elephants and mammoths diverging about half a million years later.

"We have finally resolved the phylogeny of the mammoth which has been controversial for the last 10 years," lead author Michael Hofreiter of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, told the BBC News website.

Ice age wanderer

Mammoths lived in Africa, Europe, Asia and North America between about 1.6 million years ago and 10,000 years ago during the Pleistocene epoch.

It is the longest stretch of DNA [decoded to date] from any Pleistocene species,

Michael Hofreiter

The DNA of several extinct ice age mammals, preserved in permafrost, has been analysed before, but not in such detail.

"It is the longest stretch of DNA [decoded to date] from any Pleistocene species," said Professor Hofreiter.

Maternal line

The team of researchers - from Germany, the UK, and the US - extracted and analysed mammoth DNA using a new technique that works on even the tiny quantities of fossilised bone - in this case 200 milligrams.

Some 46 chunks of DNA sequence were matched up and arranged in order, giving a complete record of the mammoth's mitochondrial DNA - the circular scrap of genetic material found outside the cell's nucleus.

It is passed down the maternal line with small but regular changes, giving scientists a window into the past.

Although the bulk of an animal's genetic information is found in the nucleus, mitochondrial DNA is particularly useful for studying the evolutionary relationships between different species.

The complete mitochondrial DNA of an extinct animal has been sequenced before but only for the flightless bird, the moa, which died out about 500 years ago.

Dan Bradley, an expert in ancient DNA at Trinity College, Dublin, Ireland, said the research was "a bit of a landmark".

"Most ancient mitochondrial DNA projects use just small parts of the mitochondria," he said.

Alternative view

In a separate piece of research, published in the journal Science, a team reports sequencing some of the nuclear DNA from 27,000-year-old Siberian mammoth remains.

Again, novel techniques were used to get at this genetic material which is normally less prevalent than mitochondrial DNA.

Hendrik Poinar, from McMaster University in Ontario, Canada, and colleagues took their sample from an animal's jawbone.

In contrast to the Nature paper, the Science team says its work shows the ice age beast to have been more closely related to the African elephant; its genetic material was 98.5% identical to nuclear DNA from an African elephant, the group said.

One of the Science article's authors, Stephan Schuster of Penn State's Center for Comparative Genomics and Bioinformatics, noted the Nature study's reliance on mitochondrial DNA.

"Mitochondrial DNA is a tiny piece of hereditary information," he told the Associated Press.

"What determines the physiology and the appearance of an organism is all stored in the chromosome [found in the nucleus], and so this tiny bit of information [carried by mitochondrial DNA] is only one-100,000th of the information that is stored on the chromosome."