Neolithic Euros Were Lactose Intolerant

According to the study, the ability to process lactose was not highly prevalent in the Neolithic era. In fact, the researchers did not find any trace of the gene variant in their samples. The total absence suggests that no more than about 40 percent of the population could possibly have been lactose tolerant 5,000 years ago—indicating that the ability to digest the milk sugar probably resulted from the advent of dairy farming. "Eight thousand years, in evolutionary terms, is nothing, especially when a genotype frequency raises from close to 0 up to more then 70 percent and, in some areas of northern Europe, [to] even more than 90 percent," [paleogeneticist Joachim] Burger says, adding he expected to find that some individuals were lactase-persistent. "The fact that we have found none demonstrates that positive selection was acting massively on prehistoric European populations and that the speed of the spread of the allele (gene variant) was enormous."

About 80 percent of the people in southern Europe now are lactose intolerant, which means that there was a relatively small window for the gene variant to have come into prevalence in northern Europe. - Scientific American