"There's zero evolutionary reason for aliens to behave altruistically towards us." But plenty of logistics and game theoretic ones. Logistics: An expansive s

"There's zero evolutionary reason for aliens to behave altruistically towards us." But plenty of logistics and game theoretic ones. Logistics: An expansive starfaring culture can garrison every rock in the galaxy within a few million years. The fact that they haven't means that either (1) no such cultures exist or will exist in our vulnerable window, in which case we are unconditionally safe, (2) the galaxy is already garrisoned and they are tolerant, in which case we are conditionally safe as long as we don't piss them off, or (3) we currently live in the special 0.1% of the galaxy's life when a hostile culture is expanding but has not reached us yet, in which case we survive mostly by random luck. The likelihood is that we are in scenario #1 or #2, but cannot know which. Game theory: A group is deterred by internal risk analysis, not external threat. A clever expansionary culture will run the logistics analysis above and decide that hostility has a horrific risk of backfiring. (For a fictional example, see Greg Bear's Anvil of Stars.)