[jwells89]

If humans have a big enough presence on a second planet for there to be wars, we’ve almost certainly spread throughout the rest of the solar system and potentially have even put generation ships en route to other star systems, so even if earth and mars are nuking each other humanity will persist.

That scenario is somewhat unlikely anyway simply because access to resources is so much greater at that point, with there being thousands of times more of anything we have on earth in the asteroid belt and other parts of the solar system.

[actionfromafar]

Isn’t it also very human to fight over control over those resources?

[jwells89]

When supply is short enough to warrant it and control is a realistic possibility, sure. Even if humans mastered spacefaring tomorrow neither would be true for many centuries. The scales involved are utterly unfathomable.