" With limited resources, a survival machine can’t afford to help all other survival machines, so it must assess whom to help, whom to exploit, and whom to leave alone. It’s a balancing act. If you’re too selfish, other survival machines will punish you; if you’re too selfless, other survival machines will exploit you. Thus, developing positive relationships—social bonds—with other survival machines is an adaptive strategy. If you are there to help your fellow group members when times are tough for them, they are more likely to be there when times are tough for you. "

― Michael Shermer , The Moral Arc: How Science and Reason Lead Humanity toward Truth, Justice, and Freedom