Your time is limited, so don't waste it living someone else's life. Don't be trapped by dogma — which is living with the results of other people's thinking. Don't let the noise of others' opinions drown out your own inner voice. And most important, have the courage to follow your heart and intuition. They somehow already know what you truly want to become. Everything else is secondary."
- Steve Jobs
Quotes like this get me thinking back to my fascination reading about Cognitive Dissonance in Psych 101.
>do you also consider it ethically acceptable to kill an individual once he has stopped procreating, since he's no longer relevant to the evolutionary game?
The evolutionary game is much more complicated than you imagine it to be. Humans have evolved to be social animals. Someone who is too old to procreate can still watch after young, pass knowledge on to them, etc., which increases their fitness. This is such a fundamental misunderstanding, you have no reason to be so confident in such matters.