As most bacteria evolve to a less deatly version of itself to promote spreading, why hasn’t TB evolved to a more harmless bacteria? It’s so old, so there was plenty of time. Killing the host seems pointless in a evolutionary sense.
Thanks!
In: Biology
TB is a relatively harmless bacterium. Can it kill? Sure. But most people you know don’t die from it, because it doesn’t harm most people. Projected over mankind, it’s not bad at all. It evolved to be harmless to most people, mildly harmful to some people for a while, and deadly to a relative few.
The main factor is that they don’t kill many hosts and most importantly they kill slowly. If the flu virus killed us immediately, the first village that got it would have been wiped out and that would have been the end of it. Instead the flu sticks around a week, during which we spread it to others. TB goes the extreme way: it lets you live for years without harming you much, so you can spread it. Eventually you may become weak enough to die.
As long as this strategy works, TB will do it.
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