"Woolly mammoths" could be brought back from extinction within two years, the scientists behind a groundbreaking resurrection project have said.
World-renowned geneticist Prof George Church and his team at Harvard University have been working for the past two years on recreating the DNA blueprint of the mammoth.
They have used DNA from mammoths that were preserved in Arctic permafrost to look for the genes that separated them from elephants, such as those with code for a shaggy coat, big ears and antifreeze blood.
By splicing the mammoth genes into the genome of an elephant embryo, the team believe they can recreate a mammoth-elephant hybrid, which would have all the recognisable features of a mammoth.
Lab tests have already shown that cells function normally with mammoth and elephant DNA and the scientists now have ambitious plans to grow a mammoth embryo within an artificial womb rather than recruit a female elephant as a surrogate mother.
Since starting the project in 2015, the researchers have increased the number of “edits” where mammoth DNA has been spliced into the elephant genome from 15 to 45.
Professor George Church, who heads the Harvard Woolly Mammoth Revival team, said: “We’re working on ways to evaluate the impact of all these edits and basically trying to establish embryogenesis in the lab.
“The list of edits affects things that contribute to the success of elephants in cold environments. We already know about ones to do with small ears, sub-cutaneous fat, hair and blood, but there are others that seem to be positively selected.”
He added: “Our aim is to produce a hybrid elephant/mammoth embryo. Actually it would be more like an elephant with a number of mammoth traits. We’re not there yet, but it could happen in a couple of years.”
The woolly mammoth roamed across Europe, Asia, Africa and North America during the last Ice Age and vanished 4,500 years ago, probably due to a combination of climate change and hunting by humans.
Their closest living relative is the Asian, not the African, elephant.
“De-extincting” the mammoth has become a realistic prospect because of revolutionary gene editing techniques that allow the precise selection and insertion of DNA from specimens frozen over millennia in Siberian ice.
Prof Church helped develop the most widely used technique, known as CRISPR/Cas9, that has transformed genetic engineering since it was first demonstrated in 2012.
Derived from a defence system bacteria use to fend off viruses, it allows the “cut and paste” manipulation of strands of DNA with a precision not seen before.
Dr Edze Westra, senior lecturer and Crispr expert at the University of Exeter, said: "What George Church is doing in trying to revive particular species I think represents a massive opportunity.
"One can also use this technology for engineering the DNA of rapidly declining species or those that are becoming too inbred to increase their chance of survival.
"I'm not sure if it is something we should be doing now, but it is definitely something that the technology offers."
Other experts argue that the technology should be used to save animals that are still alive rather than trying to bring extinct creatures back to life.
Dr Beth Shapiro, author of How to Clone a Mammoth, said scientists would never achieve a creature which was "100 per cent mammoth".
"Elephants are an endangered species, and what if you could swap out a few genes for mammoth genes, not to bring the mammoth back but to allow them to live in colder climates," she said.
Prof Church, a guest speaker at the meeting, said the mammoth project had two goals - securing an alternative future for the endangered Asian elephant and helping to combat global warming.
Woolly mammoths could help prevent tundra permafrost from melting and releasing huge amounts of greenhouse gas into the atmosphere.
“They keep the tundra from thawing by punching through snow and allowing cold air to come in,” said Prof Church. “In the summer they knock down trees and help the grass grow.”
The scientists intend to engineer elephant skin cells to produce the embryo, or multiple embryos, using cloning techniques. Nuclei from the reprogrammed cells would be placed into elephant egg cells whose own genetic material has been removed. The eggs would then be artificially stimulated to develop into embryos.
Referring to the artificial womb, Prof Church said: “We hope to do the entire procedure ex-vivo (outside a living body). It would be unreasonable to put female reproduction at risk in an endangered species.
“We’re testing the growth of mice ex-vivo. There are experiments in the literature from the 1980s but there hasn’t been much interest for a while. Today we’ve got a whole new set of technology and we’re taking a fresh look at it.”
Prof Church predicts that age-reversal will become a reality within 10 years as a result of the new developments in genetic engineering.
Yet he believes CRISPR gene editing has been overhyped.
“I don’t think it’s the cat’s meow,” he said. “It’s just another technology. To say it’s changed everything is like saying the Beatles invented the ‘60s.”
Prof Church was speaking at the annual AAAS meeting in Boston.