Ancient DNA Study Links Immune Gene Variants to Reduced Allergy Risk

org that some infection-fighting gene variants spreading over the past 10,000 years appear to reduce the risk of asthma and other allergies. Science News reported the findings, which suggest these variants do not simply heighten immune reactivity but fine-tune it against harmless triggers.

The analysis challenges the notion that modern allergies stem solely from immune systems adapted to a dirtier past.

An evolutionary geneticist who was not involved in the research offered an alternative interpretation: in ancient hunter-gatherer populations, evolution rewarded fast, aggressive immune responses to survive constant infections. He noted that later adaptations with agriculture may have tempered those responses.

The researchers analyzed human genomes from 15,836 individuals who lived between 18,000 and 200 years ago.

This examination identified hundreds of genetic variants shaped by natural selection after the shift to agriculture. Many of these genetic changes rose in frequency following the advent of agriculture and were linked to immune function. In a separate but related development, researchers reported findings in Nature on April 15.

Science News highlighted that many genetic changes identified in the Nature study pertained to immune function, reinforcing how pathogens influenced evolution as societies densified. These changes strengthened the body's first lines of defense in tissues such as the lungs and gut.

A geneticist and colleagues integrated ancient DNA datasets from the Nature study with modern genetic studies of disease risk.

The integrated data revealed gene variants that helped protect against tuberculosis, influenza, and intestinal pathogens. However, the same variants increased risk for immune-mediated conditions such as inflammatory bowel disease. Further details from the analysis showed some genetic changes reduced the activity of signaling molecules linked to allergic inflammation.

Science News reported that these shifts could explain how natural selection favored genes conferring infection protection while lowering allergy risks. The preprint and Nature study together illustrate evolution's nuanced adjustments to changing environments and disease exposures.