How Many Sexes Are There?

This past summer, controversy erupted when South African athlete Caster Semenya won first place in the 800 meter run at the 2009 World Championships in Athletics. Rumors spread that Semenya was actually a man, and the International Association of Athletics Federations ordered that she undergo gender testing. Some – especially South Africans - were livid over the testing (which has not been compulsory since 1992), while others assumed that the results would prove her “real” sex.

The international sensation that Semenya caused was no doubt painful both for her and her family. However, it did briefly highlight a fact that is too often ignored – even feared – in the world today: that there is no black-and-white method for defining human sexuality.

At around the same time that the sports industry was reeling from the Semenya case, Gerald Callahan, an immunologist/pathologist at Colorado State University, released a book titled Between XX and XY: Intersexuality and the Myth of Two Sexes. After considering the 65,000 “intersex” people born each year, he investigated the processes involved in the emergence of human sexuality. He concluded that the supposed dichotomy between male and female is nothing more than a social convention, inaccurate scientifically and damaging to society in general.

“I think the processes that generate sex in human beings are at least as complicated as those that generate fingerprints,” Callahan said in an interview for the Canadian Broadcasting Corporation’s weekly science show Quirks and Quarks in October. “And almost every one of us has a unique set of fingerprints. I began to realize that thinking of this like the on/off switch on a radio wasn’t the right way to think of it, that it’s more like bass and treble. You know the pure bass and pure treble are unachievable, but there’s a million different possibilities in between.”

Semenya is a case in point. It was reported in September that she had internal testes, no ovaries or womb, and testosterone levels that were unusually high for a female. She is what most people would call a hermaphrodite: someone with both male and female sexual organs (though from a technical standpoint, this term is also inaccurate, because hermaphrodites produce both sperm and eggs).

Semenya’s hardly unusual among athletes. Genetic screening for contestants in the Olympics, which ended after the 1996 games, often revealed that “female” athletes were genetically male. According to an article that appeared in the e-magazine Science of Sport titled “Hermaphroditism in sport: More on the latest Caster Semenya allegations,” eight women in the ’96 Olympics alone carried the SRY gene, which normally appears only on the male-associated Y chromosome.

“These eight would have presented with the same results as Caster Semenya supposedly has - no uterus, no ovaries, and (possibly) internal testes. All eight were cleared to compete [as women].”

Sexual abnormalities are not limited to the world of sports. Plenty of average people do not meet the genetic criteria for what society considers “normal.” Yet some of these people go through their entire lives without ever being recognized as different.

Some people, for instance, have only one X chromosome, a condition known as Turner’s Syndrome. Because they lack the second X that most women have, these individuals often do not have functional ovaries, and may not fully develop other sexual traits, such as breasts. Despite this, they look like females, identify themselves as females, get married, and do everything else that double-X women do. According to the children’s health organization Nemours, “Despite the physical differences and other problems that can occur, with appropriate medical care, early intervention, and ongoing support, a girl with Turner's syndrome can lead a normal, healthy, and productive life.”

On the other end of the spectrum are women with XXX Syndrome, who may in fact have up to five X chromosomes! You wouldn’t know it if you saw them on a city street, though. They might not know they have it, either; there are rarely any physical indications of their overpopulated DNA.

The same is true for those with XXY Syndrome (also known as Klinefelter's Syndrome), who are often indistinguishable from normal males. According to the National Institutes of Health, “the XXY chromosome arrangement appears to be one of the most common genetic abnormalities known, occurring as frequently as 1 in 500 to 1 in 1,000 male births…Many men live out their lives without ever even suspecting that they have an additional chromosome.”

Male/female duality debunked: karyotyping, a method of viewing a person’s chromosomal structure, reveals the extra “X” chromosome in an individual with Klinefelter’s syndrome.
Image courtesy of www.genetics.com.au (adapted to highlight extra chromosome).

“Okay,” you’re probably thinking at this point, “clearly sexual ambiguity is more ordinary than we often recognize. But certainly these abnormalities represent the vast minority of humans. Most can clearly be pegged as either men or women.”

Not so fast. If, as Callahan stated, there are a “million different possibilities in between” the traditional sexes, then where on this broad spectrum can we draw a dividing line? If neither chromosomes nor reproductive organs can help us, what makes a given individual “completely male” or “completely female?”

When we begin to look at the hormones that control male and female characteristics – testosterone and estrogen, respectively – the picture gets even murkier. All people produce both kinds, regardless of sex. Though men tend to make more testosterone than women, the actual range of production can vary wildly, even over the lifetime of a single individual.

Although there are average ranges for testosterone levels in both males and females, pinning gender to these numbers would make distinguishing between the sexes more confusing, not less. For instance, a condition in women known as hirsutism causes increased body hair and other “male” characteristics to develop. The bulk of cases involve heightened testosterone levels.

According to the nonprofit Mayo Clinic, up to 10% of women in the U.S. have some degree of hirsutism. Does that mean that these folks have slid downward on the scale of womanhood? For that matter, do all women become somehow closer to male-dom when their estrogen levels drop after menopause?

Perhaps we’re asking the wrong questions when we use all-or-nothing approach. The false dichotomy of male versus female doesn’t fit with the facts. It causes shame and hardship for people like Semenya who are nearer the middle of the spectrum. For the rest of us, we’re doomed to a perpetual anxiety about our masculinity or femininity (not to mention a pernicious social divisiveness).In light of all this, we might want to start thinking differently about how we define ourselves. After all, as Callahan notes in the epilogue to his book, “we are all intersex, living somewhere in the infinite, but punctuated, stretch between MAN and WOMAN.”