In our cushy rich modern societies, there's a lot of room between survival and ethical behaviour.
But I submit that "survival" means more than just that. We're human beings, so for us, survival requires independent thought, art, science, honesty, self-esteem, productive work, and a whole lot more.
Your mind's independent thought is ultimately the thing that ensures that your heart keeps beating. Without it, there will come a point where you can't keep making the things you need to stay alive physically.
I think Maslow's heirarchy of needs is pretty relevant here: http://en.wikipedia.org/wiki/Maslows_hierarchy_of_needs