My own experience with human populations in most worlds is pretty much like Riddick said, Stephen love. Once you lot start spreading out from your own planet you're either top of the food chain or you don't bother.

Mind you, once human colonies get properly settled, they do often start changing - sometimes naturally, more often 'cause they engineer themselves to fit into the new environments better. Once you've reached a certain level of tech capability you can make your own evolution. I've met aquatic humans with gills, for example, I've met furry ones with claws and all.

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The way you're answering some of these people makes me think you've got summat specific in mind, lovey.