Sex differences in the Dark Triad are sensitive to socioeconomic conditions: the adaptive value of narcissism in the UK, Greece, and China

Research has shown that levels of the Dark Triad (i.e., traits of Machiavellianism, narcissism, and psychopathy) vary across sex and age, with males and younger people reporting higher scores. The Dark Triad has also been found to be associated with personal economic status. We investigated whether sex and age differences in the Dark Triad varied across countries of different socioeconomic conditions. We further explored whether the dark traits predicted personal income to different extent across countries. We utilized three samples from the UK, Greece, and China (total N = 5,854), whose socioeconomic status varied from more to less developed according to the Human Development Index. Men scored higher than women on the Dark Triad, with the magnitude of sex differences being largest in the UK, followed by Greece and China. Younger people scored higher than older people on the Dark Triad, with the effect of age varying across countries. Narcissism positively predicted income, with its predictive power being significant in China and Greece but null in the UK. The results are consistent with the view that Dark Triad traits may be adaptive responses to environmental challenges. Specifically, the results suggest that sex differences in the Dark Triad and the relation between narcissism and personal income are responsive to socioeconomic conditions at the country level.