Viruses naturally mutate to become less deadly.
From what I've read, the drop in virus mortality, especially with stuff Measles and Mumps and the standard, is due to better cleanliness and hygiene.
Display MoreNatural selection favors infectivity.
The mutations aren't naturally inclined to infectivity, they're random.
Examples of virii that became more deadly over time include flu a, myxoma, h5n1, h7n9, and the hiv.
The only condition that has to be satisfied is continued spread after the initial host is dead.
Absolutely wrong.
Viruses don't become deadly. What is deadly is surprise cross-species contamination. I.E. The Spanish Flu in the 1920's was a Swine Flu that suddenly crossed over into humans. A minor bug in pigs is deadly to humans. For a while.
Then it mutates into a less deadly version AND people become more resistant.
Every single deadly virus ever is cross species.
Spanish Flu - Swine Flu (And other Swine Flues)
Bird Flu - Birds
Bubonic Plague - Rat Disease
Hemorrhagic Fever - Bat Disease
Corona Virus - Bat Disease
HIV - Monkey disease
Rabies - All mammals.
Lhyme Disease - Deer
