Skip to main content

The Journal Gazette

Tuesday, May 07, 2019 1:00 am

Setting standards

World-class sprinter sparks biological debate

Christer Watson

Caster Semenya has won several gold medals, both at the Olympics and World Championships. She competes in the 400-, 800- and 1500-meter dashes. She is, by many measures, the best in the world at what she does. However, she also recently lost her appeal to the Court of Arbitration for Sport. As a result of losing, she is forbidden from competing against other women.

Unless, that is, she lowers her testosterone level.

Semenya has been private about many of the biological details of her case. In broad strokes, however, she doesn't conform to the court's view of sex. The ruling is an attempt to distinguish between men and women. In this case, the tool the court used was testosterone level. Basically, fewer than 5 nanomoles of testosterone per liter of blood is female, more is male.

Unfortunately, this ruling is wildly misinformed and destructive. The destructive aspect is more straightforward. To compete against women, Semenya would either have to take hormones to reduce her testosterone level or have surgery. Both involve risk and the side effects are hard to predict.

Forcing medical procedures on people who are different from typical has a terrible history. It is hard for me to imagine what could justify such a requirement. This case certainly doesn't.

The criterion of 5 nanomoles of testosterone per liter of blood is not one that represents any consensus in the scientific community. In fact, the consensus is that sex and gender are pretty complicated.

There are at least six indicators of biological sex:

• Chromosomes, which typically are either XX or XY.

• Gonads, which are typically either ovaries or testes.

• Hormones, which include estrogen and testosterone.

• Secondary sex characteristics, such as breast development or facial hair.

• External and internal genitalia.

The simplest version of biological sex associates all the first examples (XX, ovaries, estrogen) together or all the second examples (XY, testes, testosterone). People's bodies are more complex, however. For example, almost all bodies have varying levels of testosterone and estrogen. Thinking of them as male and female hormones is so deceptive that it is basically wrong.

Bodies also can vary wildly on how much they trigger to a specific hormone. These differences are, in part, caused by how the hormone attaches to a cell, creating the next step in a chemical chain reaction. That is, the same level of testosterone can affect different bodies in very different ways.

As another example, some people have different chromosomes in different cells of their body. That is, some cells have XX, some cells have XY, in the same body.

As a third example, some people have XY chromosomes, but because of a variant in their AR gene, their body doesn't respond much to the triggers that lead to typical male development. That is, someone with the AR variant can have XY chromosomes but develop in a way similar to a typically developing female.

The examples of how biological sex can vary are nearly endless. The idea of male and female as clearly distinct is only an approximation of what the actual human body does. When medical experts describe biological sex as a spectrum, they are referring to this range of activity within different bodies.

Using just one biological sex criterion then, such as the outward appearance of a body or a person's testosterone level, is not accurate or useful.

The common response, one the court made, invokes fairness. I think back to how we thought of Michael Phelps as he won 23 gold medals.

I read several stories of how Phelps' body seemed practically designed to be better at swimming. For example, a leaked 2003 test showed that, after a race, the lactate levels in Phelps' blood were roughly half the level of his competitors. Lactate is related to feeling tired after quick exercise. His body apparently just doesn't produce as much of it as other people's. That certainly helped him compete in so many races back to back to back.

Is that fair? Should Phelps have been required to take hormones? No one apparently thinks so since it was widely reported on without incident.

But with determining biological sex, apparently the standards of fairness are different. The court used a simplistic version of recent science to make a ruling that was arbitrary and medically damaging. The ruling did, however, maintain the view that everyone is either a man or a woman.


Christer Watson, of Fort Wayne, is a professor of physics at Manchester University. Opinions expressed are his own. He wrote this column for The Journal Gazette, where his columns normally appear the first and third Tuesday of each month.