The first direct evidence that early Europeans were unable to digest milk has been found by scientists at UCL (University College London) and Mainz University.
In a study, published in the journal 'PNAS', the team shows that the gene that controls our ability to digest milk was missing from Neolithic skeletons dating to between 5840 and 5000 BC. However, through exposure to milk, lactose tolerance evolved extremely rapidly, in evolutionary terms. Today, it is present in over ninety per cent of the population of northern Europe and is also found in some African and Middle Eastern populations but is missing from the majority of the adult population globally.
Dr Mark Thomas, UCL Biology, said: "The ability to drink milk is the most advantageous trait that's evolved in Europeans in the recent past. Without the enzyme lactase, drinking milk in adulthood causes bloating and diarrhoea. Although the benefits of milk tolerance are not fully understood yet, they probably include: the continuous supply of milk compared to the boom and bust of seasonal crops; its nourishing qualities; and the fact that it's uncontaminated by parasites, unlike stream water, making it a safer drink. All in all, the ability to drink milk gave some early Europeans a big survival advantage."
The team carried out DNA tests on Neolithic skeletons from some of the earliest organised farming communities in Europe. Their aim was to find out whether these early Europeans from various sites in central, northeast and southeast Europe, carried a version of the lactase gene that controls our ability to produce the essential enzyme lactase into adulthood. The team found that it was absent from their ancient bone DNA. This led the researchers to conclude that the consumption and tolerance of milk would have been very rare or absent at the time.
Scientists have known for decades that at some point in the past all humans were lactose intolerant. What was not known was
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Contact: Alex Brew
a.brew@ucl.ac.uk
44-020-767-99726
University College London
26-Feb-2007