Why patriarchy?

In the annals of they had to do “research”?, Researchers identify ‘male warrior effect’“:

In experiments with 300 university men and women students, Van Vugt and his team gave the volunteers small sums of money which they could either keep or invest in a common fund that would be doubled and equally divided. None of the students knew what the others were doing.
Both sexes cooperated in investing in the fund. But when the groups were told they were competing against other universities, the males were more eager to invest rather than keep their money while the number of women contributing remained the same.

Competition between males, and groups of males, is a feature of many species. The relatively mild sexual dimorphism between human males and females in regards to size suggests that we are not a polygynous species like gorillas, though our lack of symmetry in size (like gibbons) suggests that male reproductive variance is greater than female reproductive variance (born out by comparisons of mtDNA vs. Y lineages).
Over the past few years I’ve mooted a theory for the hyper-patriarchy that is often prevelant in “civilized” cultures: my hypothesis that male social organizations scale better than female social organizations. In No Two Alike Judith Rich Harris states:

During middle childhood-what Freud called the “latency period”-girls and boys spontaneously separate into single-sex groups. As developmentalists have observed, boys’ groups tend to be larger (girls often split up into pairs or trios) and more hierarchical, or at least more overtly hierarchical. Boys appear to be more concerned about competition and status and their play is rougher….

Harris also points out that status within a male pecking order is more stable and less variant than in a female pecking orders in teenage cliques.
My conjecture is that perhaps as humans shifted from a modal hunter-gatherer lifestyle to an agricultural lifestyle, and population size increased along with residential sedentarism and the growth of pan-village institutions, male social organizations began to outflank female social organizations. In Grooming, Gossip, and the Evolution of Language behavorial ethologist Robin Dunbar hypothesized that our social cognitive faculties can intuitively hande up to 200 individuals. Dunbar offered that this was likely the maximum size of social units prior to the agricultural revolution. For whatever reason males tend to be less subtle in their social manipulations and aptitudes than females (e.g., less able to recognize nuance in facial expression), and I suspect that whatever size advantage males had could be compensated by female fluency with the details of these social networks. But as clans became part of massive tribes, nations and confederacies these intuitive social skills were at a disadvantage, and more “male” strategies of formalized rules and heuristics came into play.
As mass societies arose 10,000 years ago, finally bearing fruit in Sumer, the precursor to civilization as such, a scaffolding of institutional religions, rules and regulations arose, and I believe that all these benefited male peer groups. Even though heuristics and codes of conduct of males are clumsier and less flexibile than the intuitive social intelligence which was more a suit of female social groups, the latter by their nature could not scale beyond the clan or village, and so heuristics and codes of conduct became the framework for mass society and these are waters that males are more equipped to navigate.
But this also sheds light on the trend away from patriarchy in modern Western societies: I believe that the relative weakening of institutions, religious, ritualistic and legal, and the development of technologies which extend human social intelligence, have enabled the reemergence of female cultural styles to some level of parity with the male modality. This is also applies to the “hunter-gatherer way” in the generality, I believe that individualistic Western society is in many ways more natural than “traditional” cultures, whether it be Victorian, Islamic or Chinese. The reason that Western culture is alluring is precisely because it appeals to the human in us, our need for freedom, choice and self-actualization. Scaffolding of institutional expectations which arose during the era of pre-modern mass society constrain humans into particular behavorial tracks which are not favored by our own biases. If liberal democracy and individualist republicanism are to triumph at the “End of History” I believe it is because these forms of socio-political organization resemble the intimacy, freedom and participatory nature of hunter-gatherer society.