The blood of the extinct woolly mammoth has been brought back to life using ancient DNA from the bones of specimens found in Siberia.
In today's Nature Genetics, an international team of researchers show how it used modern bacteria to recreate the main blood protein, haemoglobin.
Analysis of the recreated haemoglobin has also answered the riddle of how the giant mammoth was able to survive the harsh Arctic conditions, says the study's co-author Professor Alan Cooper, director of the Australian Centre for Ancient DNA at the University of Adelaide.
Cooper says the technique can now be used on a range of proteins of extinct species, including the Tasmanian Tiger and even Neanderthal man, to better understand the "soft biology" or physiology of lost species.
"It is the same as if we went back 30,000 years and stuck a needle into a living mammoth," he says.
"This is true palaeobiology, as we can study and measure how these animals functioned as if they were alive today."
Back to life
To recreate the mammoth haemoglobin, the team used DNA found in the Siberian permafrost from three specimens that lived between 25,000 to 43,000 years ago.
The researchers converted the protein's DNA sequences into strands of complementary DNA (cDNA). These were then inserted into modern-day E. coli bacteria, which manufactured the authentic mammoth protein.
Cooper, who admits he thought the idea wouldn't work when approached by co-author Professor Kevin Campbell of the University of Manitoba, Canada, says it has been "remarkable to bring a complex protein from an extinct species, such as the mammoth, back to life".
He says the study shows the mammoth's blood was adapted to cope with the freezing conditions through three evolutionary changes in the haemoglobin protein that make it temperature insensitive.
These changes occurred after the populations of the mammoth migrated from their tropical origins to the Arctic about two million years ago.
In the mammoth, haemoglobin is able to continue to deliver oxygen to cells even in freezing conditions.
In humans, haemoglobin is temperature sensitive, meaning it gets sticky as it gets cold and doesn't release the oxygen resulting in cell death and conditions such as frost bite.
But those hoping this might lead to a living woolly mammoth will be disappointed.
"This is not going to bring the species back to life - we've [only] done this to one protein," Cooper says.
He says the experience of cloning shows reproduction needs a mother of the same species to carry the embryo.
And those yearning for Jurassic Park to come to life will also have to wait.
Cooper says the technique relies on DNA, which is not preserved in fossils, making it unlikely it can be used on species such as dinosaurs that died out millions of years ago.