"The mammoth we wanted to see because elephants evolved in Africa," said Kevin Campbell of the University of Manitoba in Winnipeg. So unlike some other cold-adapted mammals, mammoths were a relatively recent immigrant to the Arctic. Reindeer and musk oxen have special blood adaptations too, but they evolved separately.
"What I was most amazed by is they use a mechanism not used by any other animal," said Campbell. "That, to me is, fantastic."
It's also a great example of what's called convergent evolution, he said. That's when the same adaptation evolves separately in different animals -- like wings, which evolved separately in birds, insects and mammals.
The mammoth hemoglobin cold adaptation mechanism is actually two mechanisms, as Campbell and his colleagues report in the May 2 edition of the journal Nature Genetics. Both adaptations have to do with making sure there is enough energy available to allow the hemoglobin to release oxygen. Under cold conditions, Campbell explained, hemoglobin's grip on oxygen is a lot tighter and there is less energy available to break it free and give it to cells.