Milk tolerance "is a recent phenomenon"

Research at the University of London and at Mainz University in Germany indicates that the ability of modern human beings to digest milk is the result of the rapid spread of a gene that was not found in Neolithic man. In results published in Proceedings of the National Academy of Sciences, the researchers say the gene that produces the lactase enzyme is absent in skeletons dated between 5480 and 5000BC. Today, more than 90 per cent of people of northern European origin have the gene.

BBC