A new research from Norway published in an intriguing peer reviewed journal Behavioral Ecology and Sociobiology finds that blue-eyed men prefer blue-eyed women. Women showed no such preference for any eye-colour in men regardless of their own eye-colour. Men with other eye colours showed no such consistent preference for any eye colour in women. An interesting question, which is also the title of this article, is: Why do blue-eyed men prefer women with the same eye colour?
The researchers suggest this happens because the blue eye colour can be used as a cue of paternity. Basically, if both man and woman have blue eyes all of the children they have together will also have blue eyes. This happens because of the way eye colour is inherited. However, brown-eyed couple could easily have blue eyed and brown-eyed kids.
So, blue-eyed men can be more certain that the kids they have with blue-eyed women are really theirs and protect themselves from cuckoldry in this way. No such mechanism of assessing child’s heredity exists for men with brown eyes. The conclusion is that this preference for blue-eyed women is an evolved adaptation that allowed blue-eyed men to detect extra-pair paternity by children’s eye colour and so protect themselves from cuckoldry.