A study by staff scientist at Harvard University has revealed that over the past 10,000 years, natural selection has contributed to the evolution of nearly 500 genes in West Eurasians, affecting their appearance and susceptibility to various illnesses. The study, which used a new statistical method to identify natural selection over an 18,000-year period, found that it led to increased frequency of light skin tone, red hair, resistance to leprosy, and decreased the frequency of male-pattern baldness and rheumatoid arthritis susceptibility. The discovery contradicts the view that recent human evolution was limited. The researchers found evidence of natural selection in 479 gene variants in the West Eurasian genome dataset, 60% of which correspond with known traits in present-day people. They are now exploring other groups outside West Eurasia to understand how the global human population evolved.