Stimulating thoughts from Razib (aka “David Hume”):
But a dispositional conservatism serves more than a periodoc brake upon the inevitable march of history toward its final Utopian state. In fact the empirical record shows some cyclical dynamics in human morals and values. After all, Western liberal democracy is a throwback in many ways to the individualism of the hunter-gatherer phase of human history. I believe that the institutions and norms of communitarian “traditional” cultures were in fact ad hoc kluges which attempted to reconcile our “caveman psychology” with post-Neolithic mass society. Conservative and liberal dispositions seem to be partly hardwired; as humans we place ourselves along the spectrum. It is not simply a matter of conservatives always being a few generations behind liberals along the inevitable secular ascent up toward earthly paradise. Rather it seems possible these different political tribes are like two cylinders which serve as the motive force behind a winding and unpredictable journey.
Why is the journey unpredictable? One reason: Cultural evolution is unpredictable and the content of the beliefs and norms attractive to those with partly-hardwired liberal and conservative dispositions — the parameters of the liberal-to-conservative continuum — at any given time is a matter of the forces of cultural history as they interact with the forces of population change. Ideas and norms can't stick if our evolved minds are inhospitable hosts for them. So the fixed part of human psychology is a constraint on cultural transmission. If we find liberal individualism at all compelling, it's because we already have a taste for it. Likewise thick communitarian socialism. Culture wars are wars in part over which tastes to gratify and encourage and which to stymie and treat as a threats to decent civilization.
I agree that our conservative impulses aren't going anywhere. So, what if people with conservative impulses reproduce at a greater rate? It's interesting to think about what happens when the cultural parameters of the liberal-to-conservative continuum shifts in a liberal direction faster than dispositional conservatives can breed. And maybe something like this is Razib's idea. If the stipulated demographic trend continues–conservatives keep reproducing faster–then conservative dispositions will become relatively common and liberal ones relatively rare. At some point, this stalls further liberalization, even if it had a lot of momentum behind it. And then you'd think maybe we slide back in a “traditional,” communitarian, family-centric direction. But I guess this depends on what a native “conservative disposition” comes down to. If it's a kind of conformist hesitancy to alter the social order, then a preponderance of conservatives may do little more to lock in liberalization, just as today's conservatives praise to the Heavens the timeless verity of a bunch of extremely radical 18th-century liberal ideals.