Resurrected: woolly mammoth blood protein

Floating in a test tube in a lab in Winnipeg, Canada, is a tiny speck of woolly mammoth – a blood protein which may explain how the animals coped with the cold of an ice age.

It is one of the first proteins from a long-dead organism to be resurrected in a living cell. Other extinct animals, including Neanderthals, are sure to follow suit. Such techniques will make it possible to explore exactly how extinct animals lived, rather than making educated guesses based on reconstructed gene sequences.

Woolly mammoths died out about 3500 years ago. They shared an African ancestor with elephants around 7 million years ago, before moving north between 1 and 2 million years ago.

To cope with the cold, they developed smaller ears and fur coats. Kevin Campbell of the University of Manitoba in Winnipeg, Canada, was curious to see if their proteins had changed too. "The only way was to resurrect them," he says.

His team began with DNA from a 43,000-year-old mammoth from Siberia. Its haemoglobin, the blood protein that ferries oxygen around the body, contains three genetic sequences not found in Asian elephants - its closest living relative. Campbell's team engineered these sequences into an Asian elephant haemoglobin gene, then used Eschicheria coli to produce millions of copies of the resurrected protein.

Haemoglobin is designed to load up on oxygen in the lungs and release the gas when it gets to warmer, exercised muscles. This posed a challenge for mammoths because their muscles probably weren't warm enough to coax oxygen away from haemoglobin. The animals solved this problem by evolving a less heat-hungry haemoglobin protein that offloaded oxygen at low temperatures, the team discovered.

Campbell says his team is resurrecting other mammoth proteins, and he suspects that teams studying other ancient organisms are doing the same. Neanderthals are a prime candidate. A draft of their complete genome will be published shortly, allowing researchers to identify proteins that are different from human versions.