its hard for me to imagine the microorganism thought "hey i would be a dog i will add long ear and tails in my body!" and his sister be like "nah that's tiring i'll just evolve to mosquitos"

... What??? That doesn't make any sense... but then again, I shouldn't expect nutcases to make any sense whatsoever...

@holoknox - While I agree that what you described is impossible, that's got nothing to do with evolution. It's not about polymorphing into an existent animal of your choice, it's the way in which living things adapt to their surroundings as the generations go by, to help them survive more easily. Natural selection, "survival of the fittest", etc.

Evolution also sometimes involves living things losing parts to them that they no longer need (e.g. humans are currently evolving to lose their wisdom teeth; which each passing generation, fewer and fewer humans are developing wisdom teeth at all).

Also link, which I added a while back.

And link, which ThePrincesTale added.

It's considered to be a scientific theory rather than a scientific fact for the same reasons that gravity is also considered to be a scientific theory. But the reason I'm starting to think that it might be better to just call it a fact is because we can actually witness it happening in our own species, and the whole technicality of calling it theory seems to be confusing people into thinking that its existence is debatable or a "belief" rather than something as proven as gravity (which never gets challenged, oddly enough).

Tbh I'd be fine with calling gravity a scientific fact too.