A similar conversation took place on HN a few months ago, and a few experts pointed out that a small mutation rendered sheep (I think) totally immune to some co

A similar conversation took place on HN a few months ago, and a few experts pointed out that a small mutation rendered sheep (I think) totally immune to some common prion disease that was universally fatal to sheep without the mutation. Without being able to find the citation at this moment, it made me much less concerned about the possibility of prions becoming an intractable problem that wipes out all complex life.