Mammoth step in bringing back extinct species Resurrection of frozen extinct animals, such as woolly mammoths, could be a step closer to reality, with scientists cloning mice from the brain cells of dead mice which had been in a deep freeze for more than a decade. The cloned mice were able to reproduce normally and have healthy babies. It had been thought this approach would not work with frozen animals, because ice crystals in their cells would have damaged their DNA. But a Japanese team of researchers, led by Teruhiko Wakayama of the RIKEN research institute in Kobe, developed techniques to get around this problem, producing clones from mice which had been kept at -20 degrees for 16 years. No special chemicals had been added to the mice to cryopreserve them, a situation which would also apply to animals frozen in the wild, such as mammoths trapped in the permafrost. Dr Wakayama said this meant his team's success "offers a distinct chance to resurrect extinct animals or preserve endangered species"....