'Antifreeze' allowed mammoths to beat cold

Ancestors of both the extinct mammoth and modern elephants originated in equatorial Africa, scientists believe but mammoths migrated north between 1.2 and two million years ago just as climate change caused temperatures to plunge.

The move is surprising since elephants are not adapted to the cold.

In particular, the blood protein haemoglobin – vital for carrying oxygen around the body – is inhibited at low temperatures.

Scientists in Yorkshire and Canada investigated whether changes to haemoglobin may have been part of the mammoth's cold climate secret.

Their hunch was confirmed when they analysed preserved DNA from a 43,000 year-old mammoth whose body had been frozen in ice.

The researchers, led by Dr Kevin Campbell, from the University of Manitoba in Winnipeg, Canada, compared genes for haemoglobin from the mammoth with those of modern African and Asian elephants.

They found mutations in the mammoth genes which would have enabled haemoglobin to release oxygen at low temperatures.

The scientists wrote in Nature Genetics: "We have identified physiological properties of woolly mammoth haemoglobin that may have played an important role in the adaptation of this African-derived lineage to Arctic environments during the Pleistocene era."

British expert Professor Michi Hofreiter, from the University of York, who took part in the research, said: "Our study is the first one to reconstruct an evolutionary important, adaptive trait from an extinct species using ancient DNA."

This opened up the possibility of building up a more complete picture than would be possible using non-molecular study of of fossil bones.