关键词: 社会等级, 支配路径, 能力路径, 美德路径, 演化成因

Abstract: Across species, social hierarchies are often determined by dominance relations. In humans, where there are pluralistic value axes, social hierarchies are multidimensional systems and individuals can attain status in mainly three ways.
The dominance route exhibits the broadest range of existence and serves as the primary mechanism through which nearly all social animals enhance their hierarchical status. It employs aggression and intimidation to establish a competitive advantage by instilling fear in opponents. In this system hierarchical competition is essentially a zero-sum game, where one individual's gain comes at the expense of another's loss. The intense intrasexual competition among males for mating opportunities may be the principal evolutionary driver behind the dominance route, leading to continuous amplification of male body size as they vie for superiority, resulting in sexual size dimorphism between males and females. Neuroscience research shows that the medial prefrontal cortex may function as the decision-making center of the dominance behavior, while the amygdala potentially acts as an emotional hub which is involved in the formation of fear conditioning through observation.
By contrast, the competence route, resembles a "free trade" system, wherein individuals attain status by eliciting admiration from others through their knowledge and skills. These knowledge and skills are considered as valuable "information goods" in social communication. Group members willingly exchange their deference for the opportunity of close proximity to learning models, resulting in a mutually beneficial outcome. The competence route emerges due to the evolution of cultural learning driven by the increasing sophistication of foraging techniques. Cultural learning is a form of "high-fidelity" social learning that enables information to be transmitted "losslessly" within a group. Imitation and its neural basis, mirror neurons, which are required in cultural learning, have been observed in various non-human primates, indicating that the competence route is not exclusive to humans. But due to neurological limitations, complex movements cannot be propagated in them. In addition, although non-human animals teach (another form of cultural learning), their teaching interactions often occur between parents and children, with information being transmitted vertically rather than obliquely, as is the case with humans. Therefore, it is only human pedagogy that is based on the competence route.
Diverging from the above two paths, however, the virtue route characterized by psychological altruism is thought to be unique to human-being. While animals exhibit biological altruism (including kin altruism and reciprocal altruism), only humans possess psychological altruism, a subjective desire to benefit others. Costly altruistic behaviors serve as effective means to genuinely signal underlying desirable traits, thereby triggering emotions known as “elevation” from observers. This judgement of altruistic intention is based on an intricate theory of mind. Non-human primates, including chimpanzees, have a basic theory of mind function, but are unable to infer other individuals' beliefs about the external world. They are also better at using theory of mind in the field of competition, so they may not understand the goodwill of their peers or the intention of reciprocal cooperation. Such self-sacrificing behavior that benefits others at one's own expense cannot be attributed to natural selection. The group must give the altruists social value (high status) through cultural selection, so that the altruistic behavior can be popularized and transferred from generation to generation. This process is called cultural group selection. In this way, the allocation of respect to altruists could foster prosocial norms within the group and offer a solution to the large-scale collective action problem.
In sum, the three routes are different in the scope of existence, behavioral pattern and outcome, evolutionary cause and emotional medium. Future research could further clarify the relationship between sexual selection patterns and dominance levels in different species. Multi-discipline studies may also be adopted to explore the human environment in which the competence route has evolved, as well as the biological basis of the virtue route.

Key words: social hierarchies, dominance, competence, virtue, evolutionary cause