Why is it assumed that diseases evolve towards lower mortality? Every new disease is an evolved form of an old disease, so if that trend were true we’d expect no disease to ever have noticeable mortality.
Lower mortality is just generally more efficient, even from the disease perspective. Typhoid Mary was a great success for the typhoid, precisely because it didn’t take her out or slow her down.
Over the long run, most diseases find a balance. The balance is almost never “kill the host really fast”. Your gut microbiome is basically made out of a bunch of “infectious diseases” that play nicely with their host. That’s the normal thing. Symbiosis is efficient and normal. Depending on how you count, there are 10s or 100s or 1000s of essentially friendly bacteria species in a modern human GI tract.
When a bat virus, like SARS or Ebola, jumps to humans, the species it came from often wasn’t even really bothered by it any more… but the disease does not start out in evolutionary equilibrium with humans.
Its is usually only only when you have high enough mixing (or a new kind of mixing over barriers of separation that previously kept things separate (or some idiot not inside a BSL5 does GoF research and mixes biological reality with their scary imaginations)) that ancient equilibriums of default symbiosis seriously break down.
Ah, so mortality almost always trends downwards except when it jumps species, at which point there can be a discontinuous jump upwards. That makes sense, thank you.
Why is it assumed that diseases evolve towards lower mortality? Every new disease is an evolved form of an old disease, so if that trend were true we’d expect no disease to ever have noticeable mortality.
Lower mortality is just generally more efficient, even from the disease perspective. Typhoid Mary was a great success for the typhoid, precisely because it didn’t take her out or slow her down.
Over the long run, most diseases find a balance. The balance is almost never “kill the host really fast”. Your gut microbiome is basically made out of a bunch of “infectious diseases” that play nicely with their host. That’s the normal thing. Symbiosis is efficient and normal. Depending on how you count, there are 10s or 100s or 1000s of essentially friendly bacteria species in a modern human GI tract.
When a bat virus, like SARS or Ebola, jumps to humans, the species it came from often wasn’t even really bothered by it any more… but the disease does not start out in evolutionary equilibrium with humans.
Its is usually only only when you have high enough mixing (or a new kind of mixing over barriers of separation that previously kept things separate (or some idiot not inside a BSL5 does GoF research and mixes biological reality with their scary imaginations)) that ancient equilibriums of default symbiosis seriously break down.
Ah, so mortality almost always trends downwards except when it jumps species, at which point there can be a discontinuous jump upwards. That makes sense, thank you.