What are examples in "Fahrenheit 451" that show the innate nature of man is survival?
One example of man's desire to survive is demonstrated by Montag's wife. She is frightened by the fact that he is bringing books into their home and this puts them in danger. She does what she feels she needs to to to survive and turns him in. As they are about to burn the house, she gets into a car and leaves him standing there looking after her.
Another obvious example of Montag's desire to survive is when he kills Beatty and runs to Faber for help. He disguises his scent and runs toward the river to escape capture and death.
Most of the people in the community have adapted to the laws in order to survive. They don't question the law about no books because they realize if they do their lives are at risk.
In many ways the whole story is about man's will to live. The question becomes what would man trade for his survival. Some ran away to the woods, some conformed to the law, but in their own way each was fighting for survival.