Brain by Martin RowsonIn the past half decade, a new and intensely controversial field of science – sometimes called “neuropolitics” or “political neuroscience” – has emerged. The thrust is simple: using brain scans, researchers are finding differences, in both brain structure and brain responses, between the political left and the right.

What’s more, although the field is young, some of these differences seem consistent across studies. Thus, political neuroscience seems poised to contribute to a dramatic reevaluation of the nature of politics, locating our differences not so much in rational philosophies but rather in automatic, uncontrolled responses.

The obvious question is, should we take this research seriously, given its highly controversial nature? For instance, one of the consistent findings of political neuroscience homes in on the amygdala – an evolutionarily older limbic system component that appears to anchor our responses to fear and threat – and relates it to political conservatism. The amygdala, writes New York University neuroscientist Joseph LeDoux, “seems to do the same thing – take care of fear responses – in all species that have an amygdala. ... Defense against danger is perhaps an organism’s number one priority and it appears that in the major groups of vertebrate animals that have been studied (reptiles, birds, and mammals) the brain performs this function using a common architectural plan.” (Joseph LeDoux, The Emotional Brain, New York: Simon & Schuster,1996, p.174)

Political conservatives in the UK have been found to have a larger right amygdala – in a rather famous study commissioned by British actor Colin Firth, no less – and also to rely on it more in performing a risky gambling task. Thus, the hypothesis is that the amygdala is involved in conservatives’ greater sensitivity to threat, and a suite of political responses that flow from that – harsher views on crime and punishment, for instance, and a greater distrust of out-groups.

Political liberals, meanwhile, have been shown to have more gray matter in the anterior cingulate cortex (ACC) – a region thought to be involved in error detection, helping us switch out of automatic responses and into controlled, measured responses – and to show greater ACC firing in a task requiring one to change a habitual pattern of responding. And this, in turn, is hypothesised to relate to liberals’ greater tolerance of uncertainty and nuance, and stronger acceptance of political change.

First – like good liberals! – let’s discuss some of the limitations of this sort of research. Then, I’ll explain why I still think it provides an important avenue towards understanding the true nature of politics – and can scarcely be ignored.

Small sample sizes, small number of studies
Brain studies have nothing approaching the hundreds or thousands of subjects culled together in polls and public opinion surveys. In political neuroscience studies, samples are often fewer than a hundred individuals. (The Firth study had 118.) Such smaller sizes are accepted within the field, but obviously introduce grounds for caution. Indeed, thus far, the brain studies of left and right are far less numerous than the large number of left-right psychological studies (which long ago laid the groundwork for forays into the brain).

The baseline
Knowing about left-right brain differences doesn’t tell us much unless we know how much human brains normally diverge from each other. And the answer is quite a bit – we’re all remaking our brains daily, by living out our lives in different ways. In particular, other studies have shown the dramatic uniqueness of the brains of certain groups of highly skilled people, like musicians. So by living life a certain way, you have tremendous power to change your brain; and insofar as politics is reflective of a particular lifestyle, set of habits or way of living, it naturally makes sense that brain changes would follow from political views.

The causal arrow The prior consideration brings up a key point: just because we find left-right brain differences, it doesn’t mean that those differences predate, or cause, political divergences. Political views could also lead to brain changes – in fact, they most assuredly do. The causal arrow in this situation probably runs in both directions at once.

Brain complexity
The brain regions that have been homed in on thus far by researchers have been targeted for obvious reasons. The amygdala, in particular, sure sounds like the kind of area that would help explain left-right differences in sensitivity to fear and threat. However, the brain is staggeringly complex, and brain regions do not simply do “one thing” and nothing else. That complicates interpreting these findings.

An incomplete explanation
When we talk about conservatives, on average, having a larger right amygdala, the “on average” bit is rather crucial. In the Firth study mentioned above, the correlation between these two variables, although statistically significant, was only at .27. A correlation of 1 (or -1) means that two variables track one another perfectly. Clearly, conservatism and mere amygdala size are far less tightly correlated than that (although other political neuroscience correlations are stronger).

In other words, there are probably many liberals going around with relatively large amygdalae too. Nevertheless, for explaining a complex trait like political ideology, one that obviously has multiple causes, a correlation of .27 is nothing to sniff at.

The determinism canards When it comes to talking about the role of either the brain or one’s genes in ideology, there is an unfortunate tendency for people to leap to the conclusion that ideology is somehow “hardwired” – we don’t have a choice about it: genes and brains are destiny. This is not just false: it’s baseless.

There may not be any free will; but that’s not the issue here. The issue is whether our political views are fully determined by particular structures of the brain or, even more controversially in some ways, by genes. And in this context, a correlation of .27 between conservatism and amygdala size hardly suggests destiny.

More generally, let me reemphasise that brains change constantly, in response to new stimuli and events – and people change their political views. So to throw around terms like “hardwired” or “just born that way” in discussing these results is inflammatory and, frankly, denigrates the real meaning of the findings.

So then why, given all of these caveats, is political neuroscience still worth taking seriously?

Simple.

The research probably wouldn’t be worth taking very seriously if it was our only guidance on the deep-rooted biological or physiological differences between the political left and the political right. If these were the only studies out there, then I think the concerns I’ve just listed would probably lead them to be taken with a huge grain of salt – and rightly so.

But that isn’t the situation. Rather, the reason that researchers went searching in the brain for neuro-cognitive divergences between left and right is that psychological divergences had been documented repeatedly, over decades, especially when it comes to personality. And more recently, left-right divergences have also been found in aspects of physiology – stress responses, eye gaze patterns and disgust sensitivity – and even for genetics. Left-right divergences in moral intuitions, or automatic moral responses, are also a new area of study; here, once again, the brain seems implicated.

The brain studies discussed above, then, don’t stand on their own; they are part of a tapestry, and they fit into a broader picture. And that is why we should pay attention to them. Because they are one small part of a broader weight of evidence.

What does the tapestry look like when you stand back from it? In broad outline, politics comes to seem a fundamental reflection of human nature; and left and right come to look like the outgrowths of much more basic traits – a need to explore, say; or a need to enforce rules and protect the group from threat. Whether evolution “intended” our political divergences to exist is a vexed and controversial question; but it seems one that the new research on politics is likely to bring to the fore.

And if all of this is true, then it seems to me that it becomes necessary to walk a delicate line. There is simply no running away from scientific knowledge. This bell cannot be unrung. But interpreting its meaning is something else again. My plea: we all have strengths and weaknesses, and if politics is partly rooted in biology, then tolerance and understanding – a full understanding and acceptance of difference – become more important than ever.

The Republican Brain: The Science of Why They Deny Science – and Reality by Chris Mooney is published by Wiley