Evolution works because traits that are helpful to an individual become more common; because the individuals with those traits reproduce more.
It depends on what you mean by helpful. If you mean helpful in helping them live longer, then it is patently false. Look at peacocks feathers as one famous example.
In any species which require two to reproduce, you also have to be able to attract a mate (generally mostly on the male side), and that may require bravery, willingness to make expensive displays of power, and all kinds of other things that may go against the best way for the individual to survive.
Similarly, in a species that produces few off spring, those members also need to help ensure the off spring survive. This may involve charging into fights you could have run from so your off spring can run, searching for far more food then you need for yourself possibly at great risk, etc. In short again other traits that may go against the individuals personal survival.
It depends on what you mean by helpful. If you mean helpful in helping them live longer, then it is patently false. Look at peacocks feathers as one famous example.
In any species which require two to reproduce, you also have to be able to attract a mate (generally mostly on the male side), and that may require bravery, willingness to make expensive displays of power, and all kinds of other things that may go against the best way for the individual to survive.
Similarly, in a species that produces few off spring, those members also need to help ensure the off spring survive. This may involve charging into fights you could have run from so your off spring can run, searching for far more food then you need for yourself possibly at great risk, etc. In short again other traits that may go against the individuals personal survival.
(edit: spelling)