Political Evolution: Why Do Young Voters Lean Left? It's in the Genes

“If you’re not a liberal when you’re 20, you have no heart. If you’re not a conservative by the time you’re 30, you have no brain.” Variations of this saying have been attributed to Benjamin Disraeli, Otto von Bismarck, George Bernard Shaw, Woodrow Wilson, Theodore Roosevelt, Aristide Briand, and Winston Churchill. The thought first came, in fact, from a French statesman, François Guizot (1787–1874). Regardless of its origin, the adage raises a fascinating question: Do the young really lean left because of passions and idealism? And as people age, do they incline toward the right because they become more realistic or cynical?

For the past 10 years, I’ve studied political divisions through the lenses of evolutionary anthropology, genetics, and neuroscience. Research reveals that during their 20s people around the world experience significant shifts in the traits biologists use to describe the human personality. Specifically, “openness” declines and “conscientiousness” increases. Higher openness is associated with intellectual curiosity, a preference for variety, and voting for the left; higher conscientiousness, characterized by self-discipline and dutifulness, predicts support for more conservative politics.