But not just redheads. New research shows genetic variants linked to celiac disease, schizophrenia, light skin, a lower chance of male pattern baldness, and B blood type all arose and caught on quickly among prehistoric humans because they gave some sort of evolutionary advantage. Genes relating to body fat and cognitive performance, and resistance to various diseases such as leprosy also saw major spikes in frequency around this time, and made those who had them more likely to pass their genes on to descendants.