An anonymous reader quotes a report from the New York Times:The researchers also found that some variants, like the one linked to Type B blood, became much more common in Europe around 6,000 years ago, while others changed direction over time. For example, a TYK2 immune gene variant that may have once been beneficial later became harmful because it increased tuberculosis risk.The study also found signs of natural selection in 44 out of 563 traits. Variants linked to Type 2 diabetes, wider waists, and higher body fat have become less common, possibly because farming and carbohydrate-heavy diets made once-useful fat-storing traits more harmful. Other findings, such as selection favoring genes linked to more years of schooling, are harder to interpret.