Researchers from **Karolinska Institutet** and **Linköping University** have identified a genetic adaptation that may offer protection against the Norovirus, the virus responsible for winter vomiting disease. Their findings, based on an analysis of DNA from over **4,300 prehistoric individuals**, suggest a correlation between the spread of agriculture and the rise of a specific gene variant that protects against this illness.
The Norovirus typically spreads more aggressively during the colder months, leading to symptoms that can persist for several days. While most individuals recover quickly, the infection can recur within short intervals. However, some people possess a gene variant that significantly reduces their susceptibility to the virus. “We aimed to trace the historical spread of this protective gene variant,” stated Hugo Zeberg, senior lecturer in genetics at **Karolinska Institutet**.
Understanding the Genetic Mechanism
The gene variant in question, known as the **FUT2 gene**, plays a crucial role in the body’s ability to fend off Norovirus. It encodes an enzyme in the intestinal mucosa responsible for attaching sugar molecules to the surface of intestinal cells. The Norovirus utilizes these sugar molecules to infect the gut. Individuals carrying the defective version of this gene lack these sugar molecules, thereby preventing the virus from entering their cells.
To trace the spread of this gene variant, researchers analyzed DNA samples dating back up to **10,000 years**. They discovered that the defective gene variant was introduced to Europe around **6,000 BCE** by early farmers migrating from present-day Turkey. The spread was notably rapid between **8,500** and **5,000 years ago** as agricultural communities expanded, increasing interaction among larger populations.
“Our results indicate that the environment created by these new agricultural societies facilitated the rapid spread of the gene variant, which offers protection against winter vomiting disease,” Zeberg explained.
Modern Implications of Ancient Genetics
To further elucidate their findings, the researchers conducted studies involving modern humans by examining questionnaires and genetic material from biobanks comprising **700,000 individuals**. They found that carriers of the gene variant, particularly those with two copies inherited from each parent, rarely experienced episodes of vomiting sickness.
Additionally, researchers cultivated human gut organoids—miniature versions of human guts—using biopsies to confirm that individuals with two copies of the gene variant exhibited complete resistance to Norovirus infection. The study results are published in the journal **Molecular Biology and Evolution**.
Lead author Johan Nordgren, a docent of medical microbiology at **Linköping University**, noted, “Understanding why certain mutations arise and how they are selected helps us gain insight into their impact on our health today.” However, the protective gene variant is not without drawbacks; data from modern biobanks indicate that carriers may have a heightened risk of developing stomach ulcers and gallstones.
Zeberg pointed out that these conditions are often linked to dietary stressors and higher fat intake, factors that were likely less prevalent during the Neolithic period. He emphasized the potential clinical relevance of this research, stating that awareness of the gene variant’s protective capabilities could aid in risk assessment for those at risk of Norovirus infection.
An estimated **20%** of the Swedish population carries double copies of the FUT2 variant. “My primary focus is on evolutionary science,” Zeberg remarked. “Prehistoric DNA serves as a time machine, enabling us to explore the connections between genetic mutations and environmental changes throughout human history.”
This research was funded by various organizations, including the **Knut and Alice Wallenberg Foundation**, the **Swedish Research Council**, and the **Max Planck Society**. The study, titled “Natural selection of a virus-protective FUT2 variant following the transition to agriculture,” has important implications for understanding human evolution and health.
