i am currently reading a book on animal behavior, specifically communication. Long term studies of all highly aggressive social species (humans included ) show that cooperation is needed with the AMOUNT of conspecifics needed to feed and reproduce. Aggression to the the extent that it becomes pathological or injurious can not only kill individuals but clans or packs. If you can't cooperate, you can't protect a territory, you can't survive either through starvation or injury. Too large a population has the effect of starving itself as well. The rules and the ability to follow them, as dictated by the society of that individual results in death. I don't know that without a conscience protecting the weak has any merit at all in a natural society, it doesn't in the wild. Until recently our societies left mentally ill to die, mentally retarded or handicapped to die and wasn't so great to sick and old. Children were also considered the property of the males and could be killed if the head male felt like it without having to explain it. Women also. Either conscience is developing as we develop or who we have conscience for or about have grown as our species have grown.