Spread of farming. the origin of lactase persistence in Neolithic Age
The processing of milk to make cheese and yogurt contributed significantly to the development of dairy farming, as this represented a way of reducing the lactose content of fresh milk to tolerable levels, making a valuable foodstuff available to the human population.
Until 8,000 years ago, humans were only able to digest lactose, a form of sugar present in fresh milk, during childhood because as adults they lost the ability to produce endogenous lactase, the enzyme required to break down lactose. Shortly before the first farmers settled in Europe, a genetic mutation occurred in humans that resulted in the ability to produce lactase throughout their lives. Increasing numbers of adults in Central and Northern Europe have since been able to drink and digest milk.
“This two-step milk revolution may have been a prime factor in allowing bands of farmers and herders from the south to sweep through Europe and displace the hunter-gatherer cultures that had lived there for millennia,” specifies the article in Nature with reference to the LeCHE project…
Anthropologist Professor Joachim Burger of Johannes Gutenberg University Mainz (JGU) was substantially involved in the establishment of the EU project and its research activities. “To appreciate the significance of our findings, it is important to realize that a major proportion of present-day central and northern Europeans descend from just a small group of Neolithic farmers who happened to be able to digest fresh milk, even after weaning,” explained Burger. His team investigated the phenomenon of lactase persistence, i.e., the ability to break down milk sugar, using skeletons from the Neolithic. “Among the most exciting results obtained by the LeCHE group were the detection of milk fat residues in numerous Neolithic pottery remains and the ability to model the spread of positive selection of lactase persistence,” said Burger.
Just 5,000 years ago, lactase persistence was almost non-existent among populations in which its modern prevalence is greater than 60 percent. The researchers assume that extensive positive selection and recurrent waves of migration were responsible for this development, which — in evolutionary terms — took place extremely rapidly.
I’m not part of that group with lactase persistence. It only seems to affect me, though, if I get foolish enough to attempt ice cream.
Half my genes are from the northern climes where the spread of farming exploded – still, I managed to miss out. Fortunately, like many with lactose intolerance, I have no problem consuming yogurt – especially low fat varieties – and more cheese than I ever really need. :)