Sex, Power, and Partisanship: How Evolutionary Science Makes Sense of Our Political Divide - Hector A. Garcia 2019

Social Dominance Orientation
Equality Versus Hierarchy

Men like Trump and LePage have managed to epitomize primate out-group competition, and political scientists have developed a scale to measure it called social dominance orientation (SDO). Essentially, SDO reflects the extent to which an individual wishes his or her group to be dominant over another (versus the extent to which he or she prefers intergroup relations to be equal). The authors of the SDO scale explain that “people who are more social dominance oriented will tend to favor hierarchy-enhancing ideologies and policies, whereas those lower on SDO will tend to favor hierarchy-attenuating ideologies and policies.”⁴⁴ SDO has been consistently found to predict political conservatism and its corollaries, including economic conservatism and racial prejudice.⁴⁵

Important for our gendered political brain hypothesis is a robust finding that men score higher on SDO than women. This difference holds across age, culture, nationality, religion, income level, educational attainment, and political ideology.⁴⁶ Researchers have attempted to determine whether higher SDO among men can be accounted for by their higher status, which is the norm in most human societies. However, sex differences in SDO remain stable across cultures that vary greatly in terms of women's social standing—across the highly divergent cultures of Palestine and Southern California, for example.⁴⁷ With its male concentration, it is perhaps not surprising that those with high SDO are more likely to support war,⁴⁸ the most profound and violent means of establishing male dominance over other male groups, or preventing domination by them. Because primate male dominance struggles occur within groups as well, SDO also has implications for domestic policy, particularly around issues concerning access to resources and sexual control of women. For example, SDO correlates negatively with affirmative action, social welfare programs,⁴⁹ and support for women's rights,⁵⁰ which often concern women's sexual freedom.

It may seem strange that SDO, which measures in-group preference, predicts bias even against those with a shared national identity—why seek to keep resources from other Americans? However, competition between subgroups within a nation's borders reflects ancient adaptations for out-group competition. The human brain evolved in small, close-knit, competing bands of people, and evidence suggests that it remains calibrated to process social information within tribe-sized alliances topping out at around 150 individuals.⁵¹ Fighting units in modern militaries, for example, mirror the group sizes of early hominids,⁵² as do farming communities, business organizations, and many other social groups. When groups exceed those sizes, social cohesion and organization tend to break down.⁵³

What this means is that even though citizens technically share a national identity, our brains may have difficulty recognizing an in-group that is millions of times larger than the small band sizes in which we evolved. Instead, our Stone Age brains—already sensitive to signals of out-group difference—often encourage us to form smaller, competing groups within our national boundaries. Thus the ease with which nations can become divided between blacks and whites, Arians and Jews, Hutus and Tutsis, Sunni and Shia, Southerners and Yankees, Republicans and Democrats, rich and poor, and so on.

It may also seem strange that people of marginalized groups can become conservatives, given that conservatives tend to be higher on SDO, more xenophobic, and opposed to policies that would level the playing field for those very same groups on the margins. Here there are two important points to understand. Political orientation and its corollaries, such as SDO, are not set like eye color or some other static trait—rather, like many other adaptations they are malleable but with a predilection toward one strategy over another. This malleability allows humans to adapt to changing social, hierarchical, and environmental circumstances. Most psychological traits exhibit this kind of (limited) flexibility.

Accordingly, we also find differences in SDO according to position in the hierarchy. Meta-analytic research has found that people belonging to lower-ranking gender and ethnic or racial groups tend to reject group-based social dominance, whereas those in higher-ranking groups tend to favor social dominance.⁵⁴ Low SDO would allow someone in a subordinated position to reject the dominance hierarchy or to level the playing field by constraining dominance hierarchies altogether.

But an alternate strategy one may choose to join the prevailing dominance hierarchy even in a subordinated position (people of color, women voting for Trump, for example). Even at a cost to fitness, doing so can be a better choice than standing with a weaker (albeit more egalitarian) alliance that is more vulnerable to total annihilation by outsiders. Research finds, for example, that those near the World Trade Center during the 9/11 attacks reported growing more politically conservative, rather than more liberal, after the attacks.⁵⁵ This shift occurred across party lines and was associated with both greater patriotism and militarism. Thus, SDO, like our political orientations, is neither completely pliant nor completely rigid—it has the capacity to flex.

Another crucial point to remember is that social dominance is not only about disfavoring the out-group but also favoring the in-group. Accordingly, SDO is associated with greater patriotism,⁵⁶ which, not surprisingly, is more strongly expressed by Republicans.⁵⁷ Beyond the national flags, the parades, and the anthems, patriotism is essentially a commitment to the tribe, particularly in competition with outsiders. The ubiquity of SDO across the world underscores the fact that we navigate through our increasingly globally interfaced world, using the narrow parameters of our tribalistic brains. This mismatch poses certain challenges.

One challenge is that SDO is associated with the belief that one's group is inherently better than others, and also predicts support for intergroup aggression.⁵⁸ Humans share this pattern of in-group altruism and out-group enmity with robust chimpanzees. Jane Goodall observed that “as a result of a unique combination of strong affiliative bonds between adult males on the one hand and an unusually hostile and violently aggressive attitude toward nongroup individuals on the other,” the chimpanzee “has clearly reached a stage where he stands at the very threshold of human achievement in destruction, cruelty, and planned intergroup conflict.”⁵⁹ Among humans, tribalism is also at the root of societies being torn apart from the inside, along sectarian, racial, ethnic, or partisan lines. But once again, we typically find male competition at the center of human divisions, whether between nations or tribesmen, and in turn, we find genetic processes at the center of male competition.