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The Evolutionary Origins of Politics: An Interview with Avi Tuschman


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Many historians hold, more or less, to the blank slate theory of human behavior. That is, that the environment is overwhelmingly responsible for the way human beings vote, think about issues, and participate in politics. What does the scientific literature suggest? 

The environment does exert an important influence on people’s political perceptions and behaviors. However, dozens of findings from fields like genetics, primatology, and neuroscience show that the social sciences have greatly underestimated how intimately our political orientations also intertwine with our physiology and our genes.

The left-right spectrums that run through countries around the world have a natural history and therefore a common structure (even though they widen and shift in response to environmental stress, like economic conditions). This common origin explains why many controversial issues – like gay marriage – invariably polarize political spectrums everywhere in the same direction. If the environment determined everything, there would be at least a few countries out of the nearly 200 where the left is fighting against gay rights and the right is fighting for them.

In large populations, left-right political orientation is distributed in a normal, bell-shaped curve, similar to other natural traits like height, weight, blood pressure, and general personality dimensions – and not at all like income distribution. Even though most variation in political personalities occurs within a group, a population’s average personality traits shift slightly to the right or the left depending on the homeland of its ancestors. Even chimpanzees have rudimentary political personalities that are meaningfully similar to our own.

My aim in Our Political Nature has been to paint an accurate and illuminating portrait of our nature as political animals. I wanted to go beyond describing a series of curious scientific facts, and connect all the dots with the overarching theoretical framework of the life sciences, evolution, and to do so with the support of rigorous data rather than just-so stories.

To what extent are our political beliefs a result of genetics? 

The heritability of political orientation ranges between forty and sixty percent. This is the proportion of the variance in a population’s political attitudes that comes from genetic differences between individuals. The rest comes from the environment. Numerous studies over the past forty years have replicated this finding time and time again.

It’s important to note that heritability is not a universal constant, like the speed of light. It depends on the specific trait, the population, and the environment. For example, recent research has shown that nearsightedness has risen dramatically over the past fifty years because children are spending much less time outdoors than they used to. Because of this change in children’s environment, the proportion of myopia caused by the environment rather than by genes has risen, and therefore the trait’s heritability has decreased. Likewise, the heritability of political attitudes may vary somewhat depending on the environment.

How do we know that genetics play a role?  

First and foremost, the influence of genes on the formation of people’s political orientation has been demonstrated through twin studies. In one famous study, Thomas Bouchard at the University of Minnesota’s Center for Twin and Family Research measured the political attitudes of over 1,500 identical and fraternal twins. Most were raised together, but some of them were raised in completely different environments. The identical twins reared apart had a strong correlation between their political orientations; but the scores of fraternal twins raised separately didn’t correlate significantly.

These results show that genes play a decisive role in determining political attitudes. In other words, identical twins are more likely than fraternal twins to agree on divisive issues, precisely because they’re more closely related to one another. These findings do not mean that our genetic predisposition alone determines our opinions. But it does mean that our individual psychological differences – starting with the innate personalities that parents observe in their children – influence our political decisions more strongly than belonging to the male or female gender, or to certain demographic groups or socio-economic classes.

Second, there are already instances in which we’ve been able to isolate specific genes and link them to politically important differences in personality. Our Political Nature explains how different alleles (that is, variant forms of a gene) regulate neurotransmitters and hormones that influence moral perceptions.

Are the brains of liberals and conservatives different?  

Yes. In 2010, the widely respected neuroscientist Geraint Rees at University College London discovered that a brain scan could predict people’s political orientation. Rees and his team recruited 90 students and imaged their brains with MRIs. The students who identified with values on the right had a more developed area of the brain called the right amygdala. This brain region has an emotion-processing function sensitive to threat. The students who aligned more with left-leaning values had a more developed anterior cingulate, which is implicated in inhibition and empathy. Someone who only had the measurements of these two brain regions would be able to correctly guess whether an individual was “very liberal” or “conservative” about 72 percent of the time. It’s important to note, however, that both genes and the environment can shape the brain.

You suggest in your book that three clusters of traits divide people over politics. What are they?

Political orientations across space and time arise from three clusters of measurable personality traits. These clusters entail opposing attitudes toward tribalism, inequality, and differing perceptions of human nature. Taken together, these traits are by far the most powerful cause of left-right voting, even leading people to regularly vote against their economic interests. Our political personalities also shape our likely choice of a mate and influence societies’ larger reproductive patterns.

What beliefs do conservatives share?

Conservatives score higher in tribalism, tolerance for inequality, and tend to see human nature as more competitive. Tribalism, to be more specific, breaks down into three components: ethnocentrism, religiosity, and intolerance toward non-reproductive sexuality. Almost anywhere in the world, individuals with relatively higher measurements on this set of traits have political views associated with cultural conservatism.

Tolerance of inequality is another one of the universal factors underlying left-right political orientation. Conservatives tend to be more tolerant of inequality. One of the most useful psychological constructs we can use to measure tolerance of inequality is called “Belief in a Just World” (BJW). This is the idea that people generally get what they deserve and deserve what they get. Conservatives are more likely to agree with this politically divisive statement, while liberals tend to disagree.

The most interesting thing about tolerance of inequality and BJW is that they do not have a meaningful relationship with income. That is, being in the “one percent” or the “99 percent” has little bearing whatsoever on your political orientation, or even your preference on fiscal policy. According to the American National Election Studies (ANES), the correlation between family income and party identification for white voters in the 2012 US presidential election was a totally negligible 0.03 (it goes up to a barely significant 0.13 if you include the entire electorate). Rather, your tolerance of inequality in society runs in parallel with your tolerance of inequality within the family. Our Political Nature explains why evolution has selected for a substantial range of predispositions toward these moral emotions, which lead people to vote against their economic interests just as often as not.

What beliefs do liberals share? 

Liberals have less tolerance of inequality and a lower BJW. They tend to see human nature as more cooperative than competitive, and even as improving over time. And they score lower in measures of tribalism – that is, higher in xenophilia (the disposition to affiliate with or value out-groups), secularism, and tolerance of non-reproductive sexuality.

After World War II, researchers claimed to have discovered an Authoritarian Personality. That was pretty much discredited, but you argue that new research shows that there is such a thing as a scale that measures right-wing authoritarianism. What does it show and how can we have confidence in it?

It’s fair to say that that the Authoritarian Personality was eventually rejected in academia, but discrediting it entirely would be an oversimplification that lacks historical perspective. To start with, even the original F-scale had important successes: volunteer activists who had joined the Nazi party before Hitler’s rise to power scored significantly higher than did rank-and-file members of the German Armed Forces. The test also predicted the rise of political extremism in Serbia when taken by high school students in the early 1970s. Moreover, communists in the US and England scored much lower on this test.

Nonetheless, there were indeed some serious methodological, psychometric, sampling, and theoretical problems with the F-scale, as well as accusations of political bias. Interest in the topic waned for about twenty years, especially as psychoanalysis went out of fashion in the social sciences.

Then, in the 1980s, the Canadian psychologist Robert Altemeyer discarded the test’s psychoanalytic premises and corrected many of the technical issues. By 1986 Altemeyer’s worked received the American Association for the Advancement of Science’s Prize for Behavioral Science Research. By 1996, over fifty researchers had carried out thirty-three studies in many languages around the world, and they successfully replicated his results with his new scale. They proved the test to be both reliable (it logged similar results consistently) and valid (meaning that respondents answered the test questions in an expectedly coherent way that predicted local left-right political affiliations).

There is still a tremendous amount of work to be done though in this area. We need to stop saying that these psychometric tests measure Pre-Fascism or Right-Wing Authoritarianism; in reality, they measure left-right political orientation, which, in normal ranges, shouldn’t be pathologized. More importantly, we need to do a better job of isolating traits and modeling the multidimensional structure of political orientation.

In your book you suggest that birth order can affect our politics. Really? 

Yes, birth order exerts a modest but extremely interesting effect on political orientation, and Frank Sulloway’s research has been enormously helpful in this area. A meta-analysis of many studies on the topic has shown that later-borns are between 20 and 43 percent more likely than first-borns to support a liberal political position, to back a liberal candidate, or to campaign for a liberal social cause.Specific studies have found that later-borns score higher in Openness, lower in Conscientiousness (which may help explain the historical popularity of primogeniture in many agricultural and pastoral societies), lower levels of cultural conservatism among Japanese Americans, lower probabilities of siding with the majority among Supreme Court Justices, and higher levels of marijuana use under prohibition. The evolutionary reasons why siblings’ personalities diverge much more than their heights and intelligence are even more interesting, and explained in detail in chapters 15 and 16 of the book.

We hear a lot about ignorant voters. How many are ignorant and how many know what they’re talking about?

Surveys taken from one decade to the next reveal that a quarter of Americans are consistently unable to name the vice president of their country. What political scientists have discovered is that, in addition to the left-right spectrum, there is also a spectrum of ideological coherence that runs through the population. A landmark book in 1960 called The American Voter categorized Americans into several groups, defined by different levels of coherence in their political attitudes. This research was controversial in many respects and overly pessimistic and overly focused on the 1950s, but research on subsequent decades by political scientists like Kathleen Knight have given us a better picture of the proportions of the public that belong to these various categories.

Approximately 20 percent of the population, for example, are “ideologues” whose attitudes are highly consistent with respect to liberal or conservative principles. Lower down there is a “group benefits” level (30 percent of the population), where people think about political issues in terms of how their group may benefit with respect to others. Next, “nature of the times” voters (28 percent) associate good or bad economies with incumbents, regardless of their party. Finally, the lower 22 percent of the electorate doesn’t know or care much about politics and, given the freedom, doesn’t show up to vote.

As mentioned above, left-right orientation is distributed in a bell-shaped curve, meaning that most people are in the middle. However, the ideologues exert a hugely disproportionate force over politics, since they are more likely to be educated, interested in, or involved in politics. They are also the most politically polarized. Politicians, of course, belong to this group. But even if they didn’t, strong incentives motivate politicians to adopt attitudes that are in line with as large a segment of the electorate as possible. Over half the population is moderately or strongly polarized, so successful politicians in democratic countries must have coherent logic in their political positions.

How does knowing all this affect the way historians should write history? As historians we like to focus on the concrete, after all. We shy away from theories.

During most of recorded history, public opinion has arguably been less important than it is becoming today. The historians of the future will have to pay much more attention to the forces of collective attitudes, since new communications technologies have multiplied and polarized political media, injected steroids into public opinion, and unleashed both “Twitter revolutions” and real ones. Public opinion is subjecting leaders to increasing constraints, and therefore it behooves historians as well as today’s political analysts and forecasters of all stripes to understand the emerging science of political orientation.

Other areas of political psychology more focused on leadership analysis are also useful for historians. In particular, the work of Jerrold Post, such as his excellent book Leaders and their Followers in a Dangerous World, is tremendously illuminating of the classic triad of personality traits found in political leaders. These traits are initially adaptive for gaining power, but reaching this goal can very easily throw these same traits off kilter and lead to maladaptive behavior.

Dutch psychologist Joris Lammers has conducted a fascinating experiment that sheds light on status and moral perceptions. He had students play a political simulation in which one group was randomly assigned to become prime ministers. The other group became groveling civil servants who had to submit to the commands of the high-status prime ministers. After the game, Lammers asked them: “Is it acceptable to omit from one’s tax declaration additional wages that one earned in one’s spare time?”

The students who had played the prime ministers answered these questions with significantly more moral hypocrisy; that is, they thought it was alright to dodge taxes themselves, while judging other tax evaders harshly. The civil servants did the exact opposite; their attitudes regarding tax dodging were much more lenient toward others than toward themselves. There are several reasons why this occurs, which are explained in the last section of Our Political Nature.