Mammoths had a distinctive version of a gene known to play a role in sensing outside temperature, moderating the biology of fat and regulating hair growth. That bit of DNA likely helped mammoths thrive in cold weather, scientists say.
Scientists say they've found a bit of DNA in woolly mammoths that could help explain how these huge beasts were so well-adapted to live in the cold of the last ice age.
Woolly mammoths had long shaggy fur, small tails and ears to minimize frostbite, and a lot of fat to help stay warm as they roamed the tundra more than 12,000 years ago.
"They have this weird hump on their back, which is thought to be something like a camel hump — sort of a fat deposit that stored water and energy for the cold, dark winters," says Vincent Lynch, an evolutionary biologist at the University of Chicago.
He and some colleagues recently compared the DNA of woolly mammoths to DNA of the modern Asian elephant, which dwells in warm tropical forests and is their closest living relative.
"We wanted to identify the genetic changes that happened in woolly mammoths that make them mammoth-like," explains Lynch.
The scientists got some of their DNA from mammoth fur they bought on eBay for around $100, recalls Webb Miller of Pennsylvania State University.
"We were collaborating with Russian scientists at that time, and learned from them that the supplier was well-respected," notes Miller. "Of course, after we got a little sequence data we would have identified a fake."
In the journal Cell Reports, the research team says that when they compared this ancient DNA to the DNA of Asian elephants, they got a long list of genes with mammoth-specific changes.
But, Lynch says, here's the trouble: "We know that most genetic differences between species actually are neutral. They have no function."
To see what might be significant, they reviewed what was already known about each gene. They found one gene that was intriguing.
"Based on what we know in humans and mice, it had three functions," says Lynch. "It functions in sensing the external temperature. It functions in fat biology. And it functions in regulating hair growth."
Previous studies had shown that when you disable this gene in mice, says Lunch, "they actually prefer to live in colder environments."
The scientists did some lab experiments to see if the mammoth-specific genetic change actually did anything potentially meaningful. And it did — it turned down the activity of the protein produced by the gene.
"My perception of what's novel in the paper, as compared with other ancient genome papers (and indeed most extant-genome papers) is that we go beyond simply running computer programs and reporting the results; we make computational predictions and verify them with laboratory experiments," Miller told NPR in an email.
But could you use this information to help re-create a woolly mammoth?
"I have no interest in 'de-extinction' of the mammoth," says Miller.
Neither does Lynch.
"You could change this one gene in an elephant and maybe make it woolly mammoth-like with respect to some things," Lynch says. But to claim you'd re-created a mammoth, he thinks you'd need to make millions of changes to the Asian elephant's DNA. You'd have to put in every mammoth-specific change, plus take away everything that's unique to Asian elephants.
"And even then it's not really a woolly mammoth," he says. "It's a transmutated Asian elephant. You can never actually bring back a woolly mammoth."
Lynch thinks scientists shouldn't try — that it would be unethical. "Elephants are intelligent species. They have complex social groups. They learn from each other," he notes. "So if we bring back a woolly mammoth, who's it going to learn how to be a woolly mammoth from?"
"They're gone," Lynch says. "And who are we to bring it back?"