This is post number 8 in a series of posts on sex and gender. Humans are born with and innate nature that includes tendencies toward certain behaviors. Some tendencies are good. Some are bad. Examples include the tendency toward empathic behavior, aggressive behavior, heterosexuality, homosexuality, overeating, etc. I wrote about the differences in innate tendencies between men and women here and here. An innate tendency toward behavior (A) does not by itself provide justification for indulging in (A). If behavior (A) is negative, then it doesn't matter if behavior (A) was influenced by an innate tendency; we should still suppress that tendency. Choices are not justified by feelings, or emotions, or urges, or itches alone. Choices are justified by rationality.
Rationality is the conformity of actions to reasons. There are 2 types of rationality—articulated and systemic. Articulated rationality refers to actions that conform to specifically deliberated and calculated logic and reason within individuals. Systemic rationality is an unarticulated social process of responding to feedback from reality. Markets, traditions, and cultural norms reflect systemic rationality. Both types of rationality are valid if they are subjected to a process of authentication. In other words traditions are rational (as long as they are subject to feedback from reality), even if no individual can fully articulate the reasons behind a specific tradition. I will expound on this later.
Culture is a reflection of systemic rationality. Cultural norms evolve informally over time regardless of the intentions and articulated rationality of individuals within that culture. According to the economist and social theorist F.A. Hayek:
Tradition is not something constant but the product of a process of selection guided not by reason (articulated rationality) but by success.
Innate human tendencies are one of the inputs into systemic social processes like tradition. For example, selfish human motives can provide social benefit when someone has a selfish incentive to help other people. Everyone benefits (systemically) from the baker's bread even though the (individual) baker is self-interested. Likewise, cultural norms evolve to take into account innate differences between men and women. The following quotation from the book The Blank Slate illustrates this point:
"Mothers are more attached to their children, on average, than are fathers. That is true in societies all over the world and probably has been true of our lineage since the first mammals evolved some two hundred million years ago. This does not mean that women in any society have ever been uninterested in work; among hunter-gatherers, women do most of the gathering and some of the hunting, especially when it involves nets rather than rocks and spears." Nor does it mean that men in any society are indifferent to their children; male parental investment is a conspicuous and zoologically unusual feature of Homo-sapiens. But, it does mean that the biologically ubiquitous tradeoff between investing in a child and working to stay healthy (ultimately to beget or invest in other children) may be balanced at different points by males and females. Not only are women the sex who nurse, but women are more attentive to their babies' well-being and, in surveys, place a higher value on spending time with their children."
So even if both sexes value work and both sexes value children, the different weightings may lead women, more often than men, to make career choices that allow them to spend more time with their children-shorter or more flexible hours, fewer relocations, skills that don't become obsolete as quickly-in exchange for lower wages or prestige. As the economist Jennifer Roback points out, "Once we observe that people sacrifice money income for other pleasurable things we can infer next to nothing by comparing the income of one person with another's." The economist Gary Becker has shown that marriage can magnify the effects of sex differences, even if they are small to begin with, because of what economists call the law of comparative advantage. In couples where the husband can earn a bit more than the wife, but the wife is a somewhat better parent than the husband, they might rationally decide they are both better off if she works less than he does."
In conclusion, differences in gender roles are rational if they evolve based on (1) the innate difference between men and women, and (2) systemic rationality. Yes, that means that gender roles must be allowed to adjust—or "mutate" to use a biological metaphor—so that gender roles that diminish success within society are selected out. Long standing gender roles are not socially constructed willy nilly by insincere individuals. I think that gender roles convey information about reality.