Cow’s milk first drunk into adulthood in central Europe around 7,500 years ago
Dairy farmers living in Central Europe around 7,500 years ago may have been the first human adults to drink cow's milk - at least comfortably.
Using genetic and archaeological data, Mark Thomas and colleagues at University College London have identified the first evidence of lactase - the enzyme that allows us to digest the complex milk sugar lactose - persisting beyond the weaning years into adulthood to around 7,500 years ago, the beginning of Linearbandkeramik culture (considered the first Neolithic society in Europe). At this point there was a change from a mixed economy to one based primarily on cattle.
But, through at least four parallel evolutions starting several thousand years ago, lactase persistence spread throughout human populations. The earliest of these is known to have originated in Europe.
The genetic mutation conferring this advantage - shared by most lactose tolerant Europeans - was commonly thought to have occurred first in the northern part of the continent, where the sun shines less and people may be in greater need of the vitamin D found in cow's milk, necessary for the body's uptake of calcium.
But Thomas and colleagues now note that the trait started farther south before spreading to the north, according to the results of their computer simulation model. He suggests that two important factors triggered the evolution of lactase persistence: consistency in supply and contaminated fluids. Farmers had made their way north with domesticated crops from the Near East but these crops were not necessarily well suited for the new environment. So, as the pioneers found themselves isolated with only feeble crops and cattle as well as parasite-ridden water sources, cow's milk may have become an increasingly important staple for survival.
PLoS Computational Biology
First published in August 2009