For All Mankind is set on Mars, a planet that's pretty similar to earth and can be terraformed relatively easily. It opens you up to a bunch of other like possibilities and like a wider exploration and travel in this universe. Some of it is just like, these are the humans who have eight fingers on each hand because they've been away from Earth for so long. The lower gravity has an effect on their bone mass and body structure. And there are golds who can afford to be trained in like earth gravity and it makes their bodies physically different.