"The thing is that virus and bacteria don't work magically to harm us. They have to evolve too"
I thought it was an "everybody knows" thing that viruses and bacteria generally coevolve with hosts, so they become less virulent over time. It's when something has just become infectious that it's most likely to decimate (or worse) the population it's just arrived in.
Yeah that's also true. But it still has to evolve that infection mechanism. A virus from so long ago and from a different animal is unlikely to have the very specific mechanisms to infect us.
I thought it was an "everybody knows" thing that viruses and bacteria generally coevolve with hosts, so they become less virulent over time. It's when something has just become infectious that it's most likely to decimate (or worse) the population it's just arrived in.