Satoshi Kanazawa

The Scientific Fundamentalist

Barbie: Manufactured by Mattel, designed by evolution III

Why do men prefer women with long hair?

Posted Sep 21, 2008

Long hair

Men in general prefer women with long hair.  And most young women choose to grow their hair long.  Once again, men’s preference for women with long hair is the reason for women’s preference to grow their hair long.  The question then is:  Why do men prefer women with long hair?

Because the human fetus grows inside the woman’s body for nine months, and then the mother nurses the newborn baby for a few years afterwards, the woman’s health is crucial for the well-being of the child.  Sickly women do not make good mothers, to a significantly greater degree than sickly men don’t make good fathers.  Thus, men are interested in selecting healthy women to be the mothers of their children.  Part of the reason that men prefer  young women, besides their higher reproductive value and fertility (as discussed in my previous post), is that younger women tend to be healthier on average than older women.

How can men assess the health of their potential mates?  There were no clinics in the ancestral environment; ancestral men had to judge women’s health by themselves.  One accurate indicator of health is physical attractiveness, and this is the reason why men like beautiful women, as I mention in a previous post.  Another good indicator of health is hair.  Healthy people (men and women) have lustrous, shiny hair, whereas the hair of sickly people loses its luster.  During illness, a body needs to sequester all available nutrients (like iron and protein) to fight the illness.  Since hair is not essential to survival (compared to, say, bone marrow), hair is the first place to which a body turns to collect the necessary nutrients.  Thus, a person’s poor health first shows up in the condition of the hair.

Further, hair grows very slowly, at about six inches per year.  That means that if a woman has shoulder-length hair (two feet long), it accurately indicates her health status for the past four years, because once the hair grows there is nothing the bearer can do to change its appearance later.  A woman might be healthy now, but if she was sick sometime in the past four years, her long hair would indicate her past sickly status.  And there was nothing a woman could do in the ancestral environment to make her hair appear healthy and lustrous when she was not healthy.  This is also why older women tend to keep their hair short, because they tend to become less healthy as they grow older, and they do not want telltale signs of their current health status hanging from their heads.

If you want to see this process in action, try a little experiment on your own.  Find a female stranger in a public place (like a park or a subway station).  Observe her from behind, without looking at her face, her hands, her clothes, or anything else about her, and look only at her hair.  Try to guess her age from the condition of her hair alone, nothing else.  Once you come up with a guess for her age, pass by her, turn around to the front, and discreetly look at the woman’s face.  You will find that you are very rarely surprised by her apparent age when you look at her face and her entire body, because the condition of her hair is usually a very accurate indicator of her age.  You’ve now discovered the importance of hair as an indictor of age in the ancestral environment.