How did the woolly mammoth stay warm?
To keep warm, the woolly mammoth did more than just be woolly, new research has found.
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And sure enough, "these E. coli made Asian elephant hemoglobin," Campbell said.Skip to next paragraph
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Once the Asian elephant hemoglobin checked out, the team could try mammoth hemoglobin. To do this, they used Asian elephant RNA and a process called site-directed mutagenesis, which involves changing all the individual points in the RNA code that are different between the Asian elephant and the mammoth, effectively turning Asian elephant RNA into mammoth RNA. The newly made mammoth RNA is put in the E. coli, which spits it out what is essentially mammoth hemoglobin.
Campbell said this hemoglobin would be exactly the same as if he had taken a time machine back 43,000 years and drawn blood straight from the animal. "I can study it as if I had a fresh blood sample from that animal," he said.
The team compared the Asian elephant and mammoth hemoglobin and "we found that they're radically different," Campbell said. Just as Campbell had suspected, the mammoth hemoglobin doesn't need as much energy to offload oxygen as the Asian elephant hemoglobin does.
Interestingly, the mammoth DNA had two separate mutations that are different from those seen in mammals today.
"They used a completely different" way to solve the hemoglobin problem to adapt to the cold, Campbell said.
Why not humans?
Campbell first thought of examining mammoth hemoglobin DNA in this way when he was studying hemoglobin during a postdoctoral posting in Denmark and also happened to see a Discovery Channel show on the mammoth, and "it was this little lightbulb moment," he said.
Campbell said that one question he has frequently been asked is why human populations that live in the Arctic regions, such as the Inuit, wouldn't have evolved a similar mechanism to adapt to the cold.
The answer is three-fold: For one, humans moved to the Arctic much more recently than many other Arctic mammals, so they wouldn't have had time to evolve such a trait; also, humans don't need to evolve cold-tolerant hemoglobin, because "we make boots; we make tents" – we have our brains to help us deal with the cold, Campbell said; finally some humans do have a mutation of their hemoglobin similar to this, but it is actually detrimental, because their hemoglobin falls apart and they end up anemic.
"Humans could never even evolve this because if they did they would all be anemic," Campbell said.
Campbell said that he would like to expand on this work by trying to investigate other extinct beasts that lived in the ancient Arctic, such as mastodons, cave bears, woolly rhinoceroses and giant sloths.
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