In a very long historical perspective, political development has followed the same general pattern: the forms of political organisation employed by different groups of human beings have varied, and those forms that were more successful — meaning those that could generate greater military and economic power — displaced those that were less successful. At this high level of abstraction, it is hard to see how political development could have proceeded in any other way. What is more important, however, is to understand the ways political evolution differs from human evolution in three ways. First, in political evolution, the units of selection are rules and their embodiments as institutions, rather than genes of human evolution. Although human biology facilitates the formulation and following of rules, it does not determine their content, and that content can vary enormously. Rules are the basis for institutions that confer advantages on those societies employing them and are selected through the interaction of human agents over less advantageous ones. Second, in human societies, variation among institutions can be planned and deliberated, as opposed to random. Human beings can rarely plan for unintended consequences and missing information, but the fact that they can plan means that the variance in institutional forms they create is more likely to produce adaptive solutions than simple randomness. However, we can accept the argument that institutional evolution is not dependent on the ability of human beings to design successful institutions: random variation and the principle of selection by themselves can produce an adaptive evolutionary outcome. The third way political development differs from human evolution is that the selected characteristics — institutions in one case, genes in the other — are transmitted culturally rather than genetically. This represents both an advantage and a disadvantage with respect to the adaptability of the system. Cultural traits, whether norms, customs, laws, beliefs or values, can at least in theory be altered on the fly within the space of a single generation, as in the spread of literacy among the Danish Peasantry in the sixteenth century.
Historically, the successful forms of political development were based on
