The Farming Revolution Made Some People Immune to Norovirus

Picture this: 8,000 years ago, your ancestors are learning to grow wheat and barley, herding goats, living in close quarters with dozens of neighbors for the first time in human history. And then someone gets violently ill, vomiting for days. Within weeks, the whole village is sick. Repeatedly.

That nightmare scenario, scientists now believe, is exactly what drove a lucky mutation to spread through early farming communities. Some people carry a defective gene that makes them completely immune to Norovirus, the bug that causes winter vomiting disease. And it turns out this genetic shield arose not by chance, but because agriculture made us vulnerable in ways our hunter-gatherer ancestors never were.

“We wanted to trace the historical spread of the gene variant,” says Hugo Zeberg, a geneticist at Karolinska Institutet and the Max Planck Institute for Evolutionary Anthropology. His team analyzed DNA from 4,343 prehistoric individuals spanning the last 10,000 years, essentially rewinding evolution to watch natural selection in action.

When密Close Quarters Became Deadly

The protective mutation involves a gene called FUT2, which normally helps produce an enzyme in the intestinal lining. This enzyme decorates gut cells with sugar molecules, and Norovirus latches onto these sugars to invade. People with the defective variant cannot make the enzyme work properly. No sugar molecules, no viral entry point. The virus just slides off harmlessly.

The mutation first appeared in Europe around 6,000 BCE, carried by early farmers migrating from what is now Turkey. But here is where it gets interesting: the gene did not just trickle through the population. Between 8,500 and 5,000 years ago, it exploded in frequency.

“Our results suggest that this type of disease environment drove up the frequency of the gene variant as it protects against winter vomiting disease and confers on the bearer the advantage of not falling sick.”

The timing is not coincidental. Early agricultural societies lived in permanent settlements, often with poor sanitation and in much closer proximity than nomadic groups. Norovirus spreads through contaminated food and water, and thrives in exactly these conditions. One infected person in a small farming village could trigger an outbreak that swept through repeatedly, since immunity to Norovirus is notoriously short-lived. You can catch it multiple times in a single season.

Modern Proof in Miniature Guts

To confirm their evolutionary detective work, Zeberg’s team turned to modern biobank data from 700,000 people. Those with two copies of the protective variant, one from each parent, almost never reported having winter vomiting disease. Then they took it a step further: they grew human intestinal organoids, essentially miniature guts cultivated from biopsy samples, and exposed them to Norovirus.

The results were stark. Individuals with double copies of the mutation were fully protected. The virus could not gain a foothold.

“Ascertaining why certain mutations arise and get selected allows us to better understand how they affect our health today,” says Johan Nordgren, lead author of the study and a docent at Linkoping University.

About twenty percent of Swedes carry two copies of this protective gene, making them essentially Norovirus-proof. But evolution rarely offers free lunches. The same mutation that shields against vomiting sickness appears to elevate risks for stomach ulcers and gallstones. Modern biobanks show these conditions cropping up more frequently in people with the variant.

“These are usually linked to stress and a high intake of fat, which was probably less common during the neolithic period.”

In other words, the trade-off made sense 8,000 years ago. Avoiding repeated bouts of debilitating illness was worth a slightly higher risk of conditions that might never materialize in a low-fat, low-stress farming lifestyle. Today, with our sedentary jobs and rich diets, the calculus has shifted.

For Zeberg, the clinical implications are secondary to the evolutionary story. Prehistoric DNA, he says, functions as a time machine. “It allows us to replay evolution and see how genetic mutations can be tied to events in the human environment.” The study, published in Molecular Biology and Evolution, offers a rare window into how a single lifestyle shift, the transition to agriculture, left an indelible mark on our genomes.

And the next time Norovirus sweeps through your office or your child’s school, spare a thought for those early farmers. Their misery became our inheritance, at least for some of us.

Molecular Biology and Evolution: 10.1093/molbev/msaf243