Men find brunettes more attractive and intelligent and those are the ones they marry the study found.
‘In the Seventies and Eighties, blondes became the ideal...but more recently, there has been a backlash against blondes and the dumb blonde idea has become dominant.', noted researcher Viren Swami.
Men see blondes as easier, more needy, even dimwitted and so are not intimidated to approach them. Brunettes appear to be more intelligent, less needy and often intimidating. So once males get serious, they screw up the courage and make the effort to connect with a brunette.
Remember, in the serious business of making offspring, intelligence is most prized. And in case you were wondering, redheads are considered brunettes, just a little wilder.