original: Only traits that help us survive and reproduce are transmitted.
simplifications: only features that help us survive and reproduce are passed on. Only parts of character that help us survive and reproduce are passed on. We carry traits that help us survive and reproduce. Only traits that help us survive and reproduce are passed on. Only traits that help us survive and have babies are passed down. Only traits that help us survive and have children are passed on. The only traits that are transmitted are those that help us survive and reproduce. Only traits that help us survive and reproduce are transmitted. Only traits that help us live and breed are passed on. Only traits that help us to survive and reproduce have been transmitted.