One of the trickiest - and most controversial - aspects of psychological research tries to determine what aspects of sexual attraction are hard-wired into our brains. Studies of women have revealed an interesting paradox: while rugged men are perceived as better choices for fathering children, more women associate a less masculine man as a better choice for a long-term relationship.
A team of British and Japanese behavioural scientists even suggested that our female ancestors may have used a "mixed mating" strategy - seeking masculine men when they were at their most fertile while preferring a man with more feminine features, like a Leonardo DiCaprio, at others times.
The type of men that women find sexually attractive actually varies according to where they are in their menstrual cycle.
Research also suggests that women generally perceive men with deep voices in positive ways. Sight unseen, a booming baritone is imagined to be older, more attractive, stronger, taller, heavier and having a hairier chest than a man with a higher pitched voice. In reality, men with deep voices do tend to be heavier, but are no more likely to have the other ascribed traits.