"Professor Hardy explains the hair on our heads by saying that since only our heads remained above water, exposed to the sun, the hair remained to protect us from its rays. Other evolutionists, if they explain it at all, usually dump it on to the miscellaneous heap of unique human features labeled 'for sexual attraction'--a safe and lazy solution, since there are very few physical features which somebody at some time hasn't found sexually stimulating."
-Elaine Morgan, [The Descent of Woman]
The latter half of that is certainly true. She talks about a "vagueness of aim" in what humans find attractive in each other later in the book. "For sexual attraction" is also a good pigeonhole for some human attributes--especially in women--that on the surface makes sense but may have other evolutionary factors. An example from the text (hips) is in the queue for tomorrow.
This is a wonderful book but I wish I had read Descent of Man and The Naked Ape first for context. It was also originally published in 1972 so it has a lot of Vietnam and women's lib coloration--so it's interesting from a biological, cultural, and political standpoint.