Same thing for women - they prefer physically strong, tall men. It's also due to evolution. It boils down to survival of the fittest - the fittest had the most resources, and a mother needs resources to reproduce (mother's can't hunt while breastfeeding, so that's out of the question). Yes, it's that simple.
Same thing for men - they prefer young, sexually attractive, fertile females.
Those are our instincts anyway. We can and we do influence them consciously.