The 5,000 DNA letters spell out the genetic code of its mitochondria, the structures in the cell that generate energy.
Extinct mammoth DNA decoded
By Helen Briggs
|Mammoths became extinct in the last few thousand years
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.
Scientists have pieced together part of the genetic recipe of the extinct woolly mammoth.
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.
The woolly mammoth, Mammuthus primigenius, with its covering of shaggy hair, was adapted to the extremes of the ice ages.
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.
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.
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