Why not? Life on earth, including human life, has a tendency to sneak into every nook and cranny. On earth, much of it as I understand is because the “good lan

Why not? Life on earth, including human life, has a tendency to sneak into every nook and cranny. On earth, much of it as I understand is because the “good land” may already be occupied by others, and (initially) less competition in a new place may make it overall less inhospitable than surviving in a fertile but competitive land. After initial generations settle there, future generations will often stay in their native homelands by default unless driven out by other factors. Of course, this is just reasons for settling around Earth itself; who knows what drives the motivations of alien species?