Mammoth revival

Japanese scientist Kazufumi Goto believes that mammoth carcasses buried for thousands of years beneath the Siberian permafrost could still have intact sperm - and that this could be recovered and the DNA used to inseminate African elephants, the mammoths' closest living relative.

Woolly mammoths lived alongside humans and were widespread until the end of the Ice Age 10,000 years ago cut down their sources of food. Six have been found frozen beneath the permafrost in Siberia. According to New Scientist magazine, Dr Goto reckons that if any male specimens are found, sperm DNA could be extracted, frozen and returned to the Kagoshima University in Japan. Dr Goto has already demonstrated that DNA from dead bull sperm can be injected into cows' eggs to produce viable cattle embryos. He believes the same system could also work for mammoths, using elephant eggs. But Adrian Lister of University College London is sceptical. He points out that it needs a male carcass whose sperm DNA has survived non- medical freezing and thawing. "Everything we know about preservation of DNA in frozen tissues suggests it's smashed up into fragments," he told New Scientist.