Animals that hunt in teams are usually more successful than lone hunters. All animals that hunt in packs have rules of behavior, in other words morality. If a team member makes a kill made possible by team cooperation but hides the kill from the pack or does not share, they are outcast and not as likely to live or pass on their genetic traits.
Humans are a very special case of evolution though. Our genetic progress can not be explained by group hunting alone. The first tribal war set in motion a very high speed version of evolution. Once tribal warfare was added to the mix, the need for advanced intelligence, cooperation, group loyalty, longevity, self-sacrifice, and group morality became more important. And the cycle of selecting the most genetically advanced tribe became very time compressed. Small genetic advances that normally take many thousands of years to test out are evaluated much faster in humans. Almost every trait of modern humans is now optimized for winning at war. Those of us alive to today are the descendants of the winning warriors and war makers. We are naturally very moral alright, but only to our group for the ultimate purpose of winning at war.
Many people, but not all, have a super-sense of survival. They must survive at all costs, even after death. This motivates many people to behave especially well in the hope they will be granted eternal life. This isn't the major genetic driver of morality though. People who have no super-sense of survival can be just as moral, with no motivation at all other than the genetically programmed desire for the group they belong to win at war. Groups of 100% super-survivors are not as good at war and eventually get killed off. The best tribes at war may have a high percentage of super-survivors but they can't all be.
In fact, even in packs or tribes, the lone male takes off and survives on his own before joining up with another group, if he ever does. Plus, what about all the pioneers, who deserted their packs and struck out alone? They seem to have survived just fine, even in hostile environments. The pack is not necessary for surviving. It can in fact, be very dangerous to one's well being.
You have an idealistic view of your fellow man, which is commendable, but unrealistic. Just ask your neighbor to pay your mortgage and all your other bills this month, so that you and your genes can survive. Let me know what his reply is. Or better yet, ask one of your relatives to take them over. That might be even more intriguing. thanks, Mark