Caster Semenya and the problem of gender

As everyone has probably heard by now, champion runner Caster Semenya is being tested by the IAAF to see if she is actually qualified to compete as a woman.  The issue is complex.   During the Cold War, olympic athletes were tested, first simply by visual inspection, and later by examining their chromosomes.   The testing is now done by a panel, including various medical specialists as well as a psychologist.  How they arrive at a decision is not obvious.

Nor should it be.  The real issue here is that gender is a continuum, or more properly a whole set of continua, and the rules of sport treat it as a dichotomy.  What does it mean to be female or male?  What is gender?

Psychologists and physicians recognize a number of components to gender.  Here’s an incomplete list:

  • Genital — does the individual have a penis and scrotum, or a clitoris and vulva?
  • Chromosomal — XY or XX?
  • Hormonal — high levels of androgens or estrogens?
  • Gender identity — does the individual perceive him or herself as male or female?
  • Sexual orientation — is the individual sexually attracted to females or males?

It should be obvious on reading the list that all of these have the potential to be answered “neither” or “both” or “in between” in some cases.  And, although the items on the list aren’t independent of each other, they’re not absolutely linked either.

A quick review of sex determination in mammals:  In mammals, the default development schema is female.  All embryos start out with a cloacal opening that eventually divides into the anus and another opening.  The second one becomes the vagina in females.  If a Y chromosome is present, at about 10 weeks after fertilization a gene on the Y (known as SRY) is expressed.  The product of this gene is a regulatory protein (also known as SRY) that causes the development of glandular tissue in the sides of the opening — the area that will become the labia in females.  The glandular tissue produces testosterone, a steroid hormone that controls expression of lots of genes.  One consequence of testosterone production is that the labia majora thicken and fuse, closing the vaginal opening.   The labia minora also fuse, forming a tubular sheath around the urethra.  The urogential tubercle, a small swelling at the top of the opening, enlarges in response to testosterone and becomes the glans of the penis.   Without SRY, none of this occurs.  The urogenital tubercle remains small and becomes the clitoris, and the labia remain separate on the sides of the vaginal opening.

Fetal genital development

Fetal genital development

There’s a range of “normal” responses to SRY, so that different individuals will have varying amounts of testosterone production.  There’s a range of “normal” responses to testosterone, so that different individuals with the same testosterone levels will show different levels of expression of the genes that are regulated by it.  This means, among other things, that the clitoris can vary in size, as can the penis.  It means that around 1 to 4 % of male babies are born with incomplete closure of the penile shaft, leaving an opening on the underside of the penis; this condition, known as hypospadias, has increased in frequency in recent years.

Testosterone binds in the cell to a protein called the androgen receptor, which then binds to DNA and affects gene expression.  Androgen receptor proteins vary, as does their effectiveness in mediating testosterone’s effect.  Individuals who lack functional androgen receptors are said to have androgen insensitivity, and XY individuals with this condition may produce lots of testosterone but develop (at least superficially) as female.

Androgen insensitive XY siblings

Androgen insensitive XY siblings

I once was explaining this to a class, and after seeing this textbook photo, a student asked “Couldn’t that lead to homosexuality?”  I initially thought she meant that, being XY, they’d want to have sex with women, and that would make them lesbians.   It took a few minutes of rather confusing discussion before I realized that she meant that they’d probably have sex with guys, and being XY, that would make them gay.    I think the class found it fairly disturbing that their terminology wasn’t working in this instance.

Androgen insensitivity and hypospadias are examples of the range of conditions known as intersex.    The term itself reflects the general discomfort of people toward any admission that gender is not an absolute dichotomy.  And of course, that discomfort exists in part because a large majority of individuals do cluster close to the ends of the continuum, at least when it comes to genital morphology.

When you consider, as discussed in the recent New York Times essay on this issue, that muscular development is strongly influenced by testosterone levels and the efficiency of the testosterone regulatory response, and you consider that both of those vary considerably in individuals of either gender, it becomes clear that the IAAF is trying to fight a losing battle.

Inevitably, in many sports where amount of muscular development is important for success in competition, the women’s competitions are going to be dominated by individuals who happen to fall just as far  toward the “masculine” end of the various continua as the rules committee will permit.  When there is no absolute standard, but rather some sort of consensus based on a panel of experts in various fields, it’s going to be a messy process, and some people are going to feel that they’ve been treated unfairly regardless of what the decision is.

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