No, before civilization they did. Before established rules they did. Religion plays a role in establishing rules.
There were always rules... even going back to before civilization. They just changed and got more complicated with our growing brain. Murder was never something that that our ancestors did any easier than how we do it now.
By what shall we base our morality? Religion has played an important role in establishing morality. But by what else can we even base our morality off of?
Morality predates religion. Apes are capable of showing morality... is that because of religion?