In Philip K. Dicks story “The Gun,” space explorers land on a planet that was once inhabited by humans. What does the following excerpt tell us about the people who lived on the planet? “Only watch out. They fired on us once without even knowing who we were or what we came for. Do you suppose that they fought with each other? Perhaps they couldn't imagine anyone being friendly, under any circumstances. What a strange evolutionary trait, inter-species warfare. Fighting within the race!”