The human condition has a fundamental tension between the interests of the individual and the group that is a consequence of human nature (from our evolutionary history) and of the need for a polity (country, tribe, …) that fosters internal cooperation for mutual benefit, encourages people to follow the rules, and promotes the interests of the polity in competition with other polities.
Evolutionary theory has traditionally emphasized conflict between individuals ( nature red in tooth and claw), either between species (predator/prey) or within species (competition for mates.) From a social perspective, the most interesting thing is the development of social structures and behavioral norms that promote within-group cooperation and minimize within-group conflict.
It is, of course, foolish for an individual to physically come to blows with a group of individuals, which is why humans seek allies and then conflict in groups. The interesting forms of conflict under this heading are the more subtle individual responses to situations where their selfish interest may not coincide with the group interest. It is then that the pressures of biological evolution and cultural evolution conflict, and the outcome becomes particularly unclear.
One of the human responses to these conflicting pressures is hypocrisy: publicly advocating pro-social behavior (virtue) while privately engaging in selfish or antisocial behavior (vice.) This is more effective than simple cheating (private vice alone) because it simultaneously disarms your potential competitors.
All public speech and writings are subject to this pressure toward hypocrisy. This is especially true of the wisdom literature arising from the philosophy and religion of successful cultures. While there is indeed considerable wisdom in traditional values, we must remember that this is in effect pro-social propaganda. It is then no surprise to find that, for example, emotions are classified into “good” and “bad”, with good emotions being those that promote cooperation and self-sacrifice (love your neighbor, courage in battle), and bad emotions being those that advocate for the individual, and his or her need to survive and reproduce (anger, fear, pride, greed, lust.) See the seven deadly sins.
Humans, and so human society, cannot function without the full range of emotions, but the forces of individual and group selection must remain in some acceptable equilibrium, and social regulatory mechanisms have little need to advocate for the individual, since individuals naturally do that without encouragement. This is why moral education is so one-sided in support of pro-social behavior. Hypocrisy is often the result, because even the moral leaders are unable to live up to these ideals.
Evolutionary discussions of social behavior violate this taboo because evolutionary theory emphasizes the importance of conflict, and also because it predicts that people will find ways to promote their self-interest at the cost of the group. Some find this normalization of selfish behavior shocking. Perhaps so, but evolution describes the world that we actually live in, not the one that we desire.
Although we will not discuss conflict between groups at great length, it clearly must underlie cultural evolution. Many aspects of the cultures we find ourselves in can only be explained as the result of competition between cultures and polities. We happen to find ourselves in cultures which to some degree value and glorify military prowess, and we happen to find ourselves as individuals curiously well-disposed to the idea of risking death in battle. This is because cultures with those values and technologies, composed of such courageous individuals, out-competed peace-loving cultures of cowardly individuals.
Group/group conflict need not take the form of a decisive war. In many cases an aggressive culture with more productive lifeways gradually displaces or absorbs a competing culture.
It is an interesting speculation that the pro-social bias of wisdom literature may underly the prevalent vilification of the body. The body is highly identified with problematic selfish behavior because many of these behaviors are obviously related to nurturing or preserving the body and creating more offspring-bodies, and others are related to intra-social competition that may lead to greater reproductive success.
So as well as being highly intuitive, Mind/Body Dualism also supports this pro-social program by giving the individual a pristine soul unencumbered by the body's vile yearnings. In the absence of a distinct soul, vilification of the body might be less attractive, as then it is hard to conceive of your body as being something other than your self.