Why did woolly mammoths die out?
It has long been the view among scientists that a "small gene pool", or lack of genetic diversity, is potentially disastrous for any species.
Now studies suggest the last woolly mammoths died out after their DNA became wracked with genetic disease.
Dr Rebekah Rogers of the University of California, Berkeley, who led the research, told BBC Radio 4's The about the study.
- From the section Science & Environment