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The Evolution of Female Anatomy

Evidence that the clitoris evolved to enhance sexual and reproductive function.

In a recent News Hour segment on PBS television, doctors and researchers pointed out that female sexual topics were largely ignored in medical school where mostly male lecturers knew almost nothing about the topic and chose to gloss over it. Instead, they focused on male sexual anatomy and its various diseases and dysfunctions.

Urologist Rachel Rubin noted that when she attended medical school, there were 27 fields of specialization in men's sexual health but only one dealing with female sexual health. This meant that women experiencing sexual difficulties literally had nowhere to go in the medical field.

Why was women's sexual health so thoroughly neglected? The PBS segment offers two possible explanations. The first is that physicians and scientists looked upon women primarily as baby-producing machines. The other is that female sexual pleasure was perceived as shameful.

In some societies, it was, and is, perceived as such a problem that female genital mutilation was used to reduce sexual pleasure, thereby minimizing marital infidelity.

One often hears that the clitoris is the only organ whose sole function is generating pleasure. This conclusion may underestimate the role of sexual pleasure in pair bonding and reproductive success.

Evolution of the Clitoris

Knowledge of the basic anatomy of the clitoris remains fairly limited and its function is even more obscure(1). Many doctors avoided examining the clitoris because it made their patients feel uncomfortable. Consequently, there was a near complete neglect of female sexual health.

Most female mammals appear to have an external glans clitoris that is anatomically, and developmentally, analogous to the male penis. This analogy is most obvious in the case of hyenas where the clitoris is enlarged and closely resembles the penis of males. These external organs are used in social display where an erect organ signals dominance. (Females of this species outrank males).

Some biologists suggested that the clitoris is present in women as a developmental side effect of males having penises. They pointed out that men have nipples for similar reasons—that males and females develop similar breast morphology that leads to lactation only in women.

This analogy is unsatisfying for different reasons. One is that men have functional mammary glands and not just an external nipple. This fact emerges when they receive hormone treatments that block testosterone or increase progesterone. Such treatments may induce lactation. We do not know why that latent capacity exists in men but it establishes that there is more to this phenomenon than a small external nipple.

The True Function of the Clitoris

There is a lot more to the clitoris than the small external organ that used to be dismissed as a diminutive developmental side effect of the penis.

About 90 percent of the clitoris is below the surface. This consists of two bulbs, and two arms containing erectile tissue. Anatomists note that the entire structure is heavily innervated and therefore highly sensitive to tactile stimulation.

The intricate functional characteristics of the clitoris imply that these were produced by natural selection to improve sexual, or reproductive function. If so, then they cannot be merely a developmental side effect of penis development.

What is the function? When we hear it is only for pleasure, this often implies that it is otherwise unimportant. This conclusion is contradicted by research on pair bonding in other species.

“Solely for Sexual Pleasure”

Research on other species established that sexual intercourse plays an important role in forming pair bonds, as illustrated by comparisons among monogamous and polygynous voles. This implies that sexual pleasure affects parental investment and reproductive success.

Humans are mostly monogamous and sex may be the hedonistic glue in a relationship. If this is true of the pleasure produced in the penis, why would the pleasure produced in the clitoris – an organ with remarkable functional similarity – be any different?

Whatever else one says about humans, our reproductive system worked better than that of any other primate. Indeed, our numbers are so great that we pose the greatest single threat to the planet(2).


1. Gross, R. E. (2022). Vagina Obscura. New York: W W Norton.

2. Barber, N. (2022). The restless species: Cause and environmental consequences of human adaptive success. Portland, ME: Trudy Callaghan Publishing.…

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