It took more than being woolly for woolly mammoths to survive the wintry climates in which they lived. A new study in Nature Genetics suggests that the weighty mammals had hemoglobin in their blood that could keep oxygen moving even at low temperatures, giving them a kind of "antifreeze" blood:
For the mammoth, this meant that they could keep extremities cool and concentrate heat internally, minimizing heat loss. In addition, it meant that when food was scarce they could live on less of it since they didn't need as much heat (or calories) to move the oxygen to the tissues [The Guardian].
