Are you lactose-intolerant? Most people are, including large majorities in Africa and Asia. Only in a handful of European countries (and their former colonies) can most adults safely drink milk, and why that is may hold the key to that continent’s early cultural history.
Farmers from the Middle East first brought agriculture to Europe about 8,000 years ago. But archaeologists remain unsure whether indigenous hunter-gatherers adapted peacefully to planting and herding, or whether they were simply displaced. At the heart of the matter is who modern Europeans are most related to—Middle Eastern farmers or local hunter-gatherers. To get a closer look at this question, a research team of archaeologists, geneticists, and chemists from Europe and the U.S. found they had to start with lactose, says Andrew Curry in Nature (July 31, 2013).
Not long after farming got its start on the continent, a genetic mutation that allowed adults to tolerate dairy products, called lactase persistence, emerged in central Europe and, along with agriculture, began spreading rapidly. The ability to tolerate milk proved surprisingly important to these early farmers. Not only could adults rely on dairy products during poor harvests, their offspring was healthier and more fertile. One 2004 Harvard Medical School study called the advantage “among the strongest yet seen for any gene in the genome.”
For the research team, which calls its project Lactase Persistence in the early Cultural History of Europe, or LeCHE, this mutation had everything to do with how farming spread through Europe. Although it emerged after agriculture first appeared in southeastern Europe, lactase persistence gave early farmers a distinct advantage as the practice took over the continent.
The team also found dairy farms to be full of clues of this early exchange. Examining Neolithic cattle bones in northern Europe, LeCHE researchers found they had much more in common with Middle Eastern cows than the wild aurochs once found in Europe. Together with similar findings from human DNA, the evidence suggests that hunter-gatherers in Europe didn’t simply adopt early agriculture but were displaced by migrating farmers. And once armed with the lactase mutation, the farmers were unstoppable. Within a thousand years—a short time on a prehistoric scale—dairy farming became a huge part of Europe’s emerging economy.