The arrival of agriculture coincided with a sharp rise in a gene variant that protected against the virus that causes winter vomiting, researchers from Karolinska Institutet and Linköping University report after analyzing DNA from over 4,300 prehistoric individuals and cultivating “mini guts.”

Winter vomiting disease is caused by the norovirus, which is most virulent during the colder half of the year. The infection clears up after a couple of days, but the protection it provides is short-lived, meaning that the same person can repeatedly fall sick in a short space of time. But some people cannot succumb to the virus, thanks to a particular gene variant.

“We wanted to trace the historical spread of the gene variant,” says Hugo Zeberg, senior lecturer in genetics at the Department of Physiology and Pharmacology, Karolinska Institutet, and researcher at the Max Planck Institute for Evolutionary Anthropology in Leipzig.