Many theorists in psychology, anthropology and biology have noted that human beings and their hominid ancestors survived and prospered as species only because they lived in cooperative groups.

• 很多心理学、人类学和生物学方面的理论家们都注意到人们和他们的猿类祖先作为物种生存和繁衍下来仅仅因为他们以合作群体的方式生存。