From abortion rights to gun control, there are plenty of issues liberals and conservatives can’t see eye to eye on but next time you find yourself in a deadlock with your Trump-supporting relative, know that it’s not their fault – their political orientation could be the product of their brain shape, specifically the size and volume of their amygdala.
Psychologists examined brain scans of 93 volunteers to compare their politics to the structure of their amygdala, which is, in essence, the brain’s emotional control center. As well as regulating our emotions, emotional behavior, and motivations, this region of the brain affects our social functioning and attitudes towards social hierarchies.
Interestingly, the researchers discovered that volunteers who skewed to the right on the political spectrum also displayed higher volumes of gray matter in the left and right amygdala. Their results were published in Nature Human Behavior.
It all comes down to a concept called “social justification”, which the study authors describe as favoring “the social, economic, and political status quo”. It “may promote vigilance to social hierarchy and a preference for ideologies that characterize extant inequality as legitimate and necessary.”
People who score highly on this particular psychological trait are more likely to agree with statements like “Everyone has a fair shot at wealth and happiness” and “Society is set up so that people usually get what they deserve” and disagree with statements such as "American society needs to be radically restructured.” While not an indication of right-wing politics per se, previous studies have found a strong correlation between social justification and conservativism.
Initially, the researchers compared the responses of 48 Caucasian adults (58 percent female) to statements like the ones above measuring social justification to the size of the amygdala in their brain scans. They also asked volunteers to rate their politics on a scale of one (extremely liberal) to eleven (extremely conservative). Next, they replicated the study on a group of 45 adults (67 percent female) from a more diverse background.
According to the researchers, it was social justification rather than specific political ideology that best predicted the size of the amygdala in both studies. Higher scores in a social justification survey were also linked to greater conservatism.
The study was small and correlational and is no way definitive but it does support older research that has found a strong association between politics and brain structure, including one (bizarrely) commissioned by British actor Colin Firth that discovered liberals tend to have larger anterior cingulate cortexes while conservatives tend to have larger amygdalas.