I don't think that nature conspires to kill Pepe in Steinbeck's short story. The reality is that Pepe believes himself to "be a man." This refrain is heard before he goes into town and when he comes back. Nature becomes the testing ground for Pepe to assess whether he really has matured or rather thinks he has. The fact that he loses everything that he took in order to help him and that he is not able to survive the conditions in which he finds himself is not a conspiracy, as much as a reflection of how difficult the world is. Being mature and being an adult in the natural world is one of struggle and part of maturation seems to be understanding what this struggle entails. Naturally, he is killed by human beings. The social forces that hunted him down and shot him ended up killing him. I don't see nature as forcing the hand of conspiracy to kill him. Yet, I see the natural world function as a testing area for him. It serves as one last teacher to make clear what it means to struggle and what it means to understand the implications of maturity. His rising to his feet at the end of the story helps to bring this about. Perhaps, this ending reflects that he has "become a man," something that nature helped to bring about.