Actually for long term survival the good and evil have to approximately balance. A population with too much evil ends up destroying itself, too little they will be conquered. We may have evil built into our DNA, but we also must have team player qualities, i.e. morals. We invented jail to limit the number of people with too much evil. I'm not sure why saints are so far and few between, but there must be some evolutionary reason for their rarity. Possibly because they die poor virgins? Of course how we got here doesn't mean how it will be in the future. With growing socialism, genetic engineering, better health care, the evolutionary rules have changed. Evolution as we've known it has largely ended, for now anyway.