I wouldn't put a limit on human ingenuity to overcome this problem. Evolution has already become a tool for humanity to further itself. See: Farming. It will on

I wouldn't put a limit on human ingenuity to overcome this problem. Evolution has already become a tool for humanity to further itself. See: Farming. It will only come under greater human control as genetic engineering continues developing. Maybe one day, we will be able to turn this "death gene" off. What happens then? If a novel infectious disease pops up, sure it will cause widespread death, but it's highly unlikely it will cause the death of the species. We'll either save a few of us in some deep underground bunker, or we'll figure out how to beat it. That's really the only Earth-based threat that can still threaten the species as a whole. Evolution operates on a scale of decades and centuries. Human ingenuity operates on much shorter time scales. We don't fall under natural selection anymore. We are the ones who select now. We don't need some of us to die for us to adapt. We can adapt to every single biome and environmental condition on Earth without waiting for genetic variation to produce individuals who can. Evolution may need death to work, but we no longer need evolution for us to work.