By Rebecca Morelle
Science reporter, BBC News
The coat colour of mammoths that roamed the Earth thousands of years ago has been determined by scientists.
Some of the curly tusked animals would have sported dark brown coats, while others had pale ginger or blond hair.
The information was extracted from a 43,000-year-old woolly mammoth bone from Siberia using the latest genetic techniques.
Writing in the journal Science, the researchers said a gene called Mc1r was controlling the beasts' coat colours.
This gene is responsible for hair-colour in some modern mammals, too.
In humans, reduced activity of the Mc1r gene causes red hair, while in dogs, mice and horses it results in yellow hair.
Using ancient DNA extracted from the excavated mammoth bone, the international team of researchers were able to look at the variations in copies of the Mc1r gene.
Dr Michael Hofreiter, an author on the paper and an evolutionary biologist from the Max Planck Institute for Evolutionary Anthropology, Germany, said analysis revealed two different versions of the gene were present - a fully active and a partially active version.
The researchers propose that hair coloration in mammoths is likely to have been determined in the same way as in present-day mammals.
Light-coloured fur camouflages mice on the beaches of Florida
This means that mammoths with one copy of the active gene and one of the partially active gene would have had dark coats - most likely dark brown or black.
While mammoths with two copies of the inactive gene would have had paler coats - possibly blond or ginger.
The scientists said they were unsure why different-coloured mammoths existed.
Other research published in the same journal found that beach mice, whose coat colour is also controlled by the Mc1r gene, have varying colours for survival reasons.
The researchers said Florida beach mice were lighter than their mainland cousins because their pale fur helped them to hide from predators in their sand-dune habitat.
But Dr Hofreiter said it was unlikely that mammoths had varied coats for camouflage.
He said: "They were very big - so even a blond mammoth would have been easy to spot."
Woolly mammoths (Mammuthus primigenius) were common about 50,000 years ago, during the late Pleistocene epoch.
They were about the size of an Indian elephant, but with shaggy woolly coats and tusks measuring over 4m long. They are thought to have died out about 4,500 years ago.
Commenting, Pleistocene mammal expert Adrian Lister, of University College London, UK, said the study was of tremendous interest.
The preserved specimens of mammoth hair that had been unearthed were "usually a kind of orangey colour", but this could not be trusted, explained Professor Lister.
"In most textbooks of the woolly mammoth, hair is usually shown as auburn to orangey colour because that's the colour of the hair when its dug out of the ground, but that could be an artificial result due to the burial or the leaching out of pigment," he said.
"Whether they were brown or orange isn't hugely important; it's the precedent and the potential that's important to me."
Dr Mark Thomas from the Centre for Genetic Anthropology, also at UCL, agreed: "It's the first time anybody has taken an extinct species and been able to say something about how the animal appears from its DNA.
"The possibilities from there are endless. For example, in future we might be able to look at genes that affect behaviour and come to conclusions about the animal's temperament."