The media reported last week that genes from Neanderthals protect many of us against severe Covid-19. Those genes actually come from Denisovans too: another early human species. Unfortunately, a different set of Neanderthal genes increases our chances of serious Covid. This post goes behind the news and looks at our connection to these two prehistoric creatures, as well as their genes’ impact on Covid risk. It also looks at those genes’ frequency among modern ethnic groups.