NICE guys knew it, now two studies have confirmed it: bad boys get the most girls. The finding may help explain why a nasty suite of antisocial personality traits known as the "dark triad" persists in the human population, despite their potentially grave cultural costs. The traits are the self-obsession of narcissism; the impulsive, thrill-seeking and callous behaviour of psychopaths; and the deceitful and exploitative nature of Machiavellianism.