Sport's gender bender question: X and Y chromosones

THE science of sex holds clues for sorting men from women in the competitive world of athletics.

WHEN Caster Semenya sprinted across the 800m finish line at the World Athletics Championships in Berlin last month, she left behind more than a trail of competitors. Confusion and controversy have followed the boyish 18-year-old South African, who won her race in 1min 55.45sec.

It was the best women's time this year. But was it won by a woman? That's the key question swirling around Semenya, who was raised as a female and, until last month, was unaware of any abnormalities.

But now Semenya, like people worldwide, has read leaked reports of gender testing the runner was asked to undergo just hours before her record run. The claims: she's a hermaphrodite with internal testes and three times the level of testosterone of an average woman.

Even if the findings are confirmed by the International Association of Athletics Federations at its council meeting next month, questions will remain. Do intersex women such as Semenya have a competitive edge? Should such athletes be allowed to compete with women? What does sex mean, anyway?

Scientifically, sex isn't black or white, male or female. About one baby in 4500 is born in a grey zone, with sexual anatomy that doesn't fit the typical definitions.

According to developmental biologist Peter Koopman from the University of Queensland, sex is defined by chromosomes, tiny structures in the body's cells that carry each person's genetic blueprint.

Typically, males have an X and a Y chromosome and females have two Xs.

``Usually, during development genes in these sex chromosomes regulate the development of testes and ovaries in an embryo,'' Koopman says.

``Once that happens the testes or ovaries produce male or female hormones, which then go on to (determine) whether the babies look like a male or female.''

Koopman explains that in early stages of foetal development the hormone testosterone triggers the formation of male sex organs such as the penis. The female foetus, which has no testosterone, develops sex organs such as ovaries and a vagina. ``It's a very complicated process and there are many points where the process can break down. The result is that the baby is neither a male or female but something in between.''

These yin-yang babies are considered to have one of 20 to 30 disorders of sexual development, DSDs, caused by genetic or hormonal abnormalities during pregnancy. They're manifested by unusual external genitalia, internal organs, gonads, physical appearance and body structure. ``A person can have any combination of these,'' Koopman says.

``Some children are born where they appear outwardly to be male or female and it's only later that it transpires there is a problem there,'' he says. ``This is the situation with this athlete. When born, most likely she would look like a typical female,'' he adds, quickly noting that until the medical results are released that's speculation.

Koopman says it's possible that Semenya has true gonadal intersex, also called true hermaphroditism. The condition occurs when a person has either one ovary and one testis, or has one or two ovotestes, gonads containing both ovarian and testicular tissue. Ovotestes occur in about one in 83,000 births, for reasons that are poorly known.

``If this person's gonads are not ovaries, as one might expect in a typical female, they may contain part testes or complete testes, in which case they will be producing testosterone,'' Koopman says.

``That would result in masculinising skeleton and muscles, which would give someone a competitive advantage athletically over a typical female.''

Media reports have also suggested Semenya may have androgen insensitivity syndrome, in which an individual has testes and produces testosterone but doesn't have functioning testosterone receptors that can respond to the hormone.

If so, the teenager doesn't have a sporting advantage, because although her body would produce high amounts of testosterone, the hormone couldn't perform its regular function. That's why the IAAF has a policy of allowing women with AIS to compete against women. However, it has no policy on most other DSD conditions, including true gonadal intersex.

According to Koopman, it's unlikely that Semenya has AIS: ``Her body has been partially masculinised and if it was AIS the body couldn't respond to testosterone so it would look typically like a female body''.

So the decision of whether or not DSD athletes should compete against women can be based on two types of guidelines, one dictating what constitutes a male and female, the other sorting sexes on the basis of an unfair advantage.

Both approaches are troublesome. Why arbitrarily assign them a sex if their condition doesn't affect sporting performance? Conversely, does deeming that a DSD gives an unfair advantage artificially limit what natural sportswomen might achieve?

While Semenya's performance was impressive, it by no means falls outside the realm of typical female accomplishments. Her time was two seconds below the women's world record for 800m, earning her only 14th place in the list of best 800m female sprinters.

Scientific advances pinpointing the physical differences in male and female bodies that contribute to athletic performance may provide a solution. They may help predict the advantages, if any, resulting from specific DSDs. And while still classifying sexes into cookie-cutter moulds, at least decisions would be based on objective criteria.

Case in point: muscles and testosterone. In 2000, Harvard University researchers reported that faster sprinters apply greater ground forces in each stride.

``Ground force power is the amount of force that your body can produce when it hits the ground to move forward,'' explains Philo Saunders, senior physiologist at the Australian Institute of Sport. ``If you can produce more force on the ground, you can produce more propulsion forward.''

Muscles are needed for ground force power. ``Guys will have big and generally stronger muscles that are capable of producing more force,'' Saunders says. And testosterone -- which men produce in abundance -- helps boost muscle mass and power output. Differences in individual muscle fibres in men and women may also contribute to power output.

Typically, males also have larger lung capacity and oxygen consumption than females. That's also indirectly linked to testosterone levels.

``Maximal oxygen consumption is the amount of oxygen you can deliver to your muscles; the higher the value the better you are at endurance,'' Saunders says. ``Females are at a bit of a disadvantage there.''

Koopman isn't convinced these objective measures can help create guidelines for sorting DSDs. ``Even typical females will have a range of testosterone levels. Its just one's good luck if one is on the high end of the spectrum,'' he claims.

Once experts start using scientific measures to determine unfair advantages, where do they stop? Athletes have differing levels of erythropoietin, a hormone that increases production of oxygen-carrying red blood cells. It's also linked to genetic conditions such as Marfan's syndrome, which causes women to grow to heights of 2.13m.

Eric Hollingsworth, head athletics coach at Athletics Australia, agrees with Koopman: ``If this natural situation is giving (Semenya) an advantage, then so be it, because everyone (is selected for teams) on visible advantages.

``I would look for a basketballer (who) is seven foot.''

Social factors also drive many male-female differences in sporting prowess. For instance, Saunders says more males participate in all levels of sport, increasing competitive experience and skill.

That fits with earlier scientific predictions that, over time, women would outrun men in a variety of distances, including the 800m. While this claim remains contentious it illustrates that defining what typical women and men can do is fraught with difficulty.

So what should bodies such as the IAAF and the Australian Olympic Committee do about cases of ambiguous sexuality, bearing in mind that many people with such conditions see no ambiguity at all?

Beverley Hill, associate director of equity and diversity at the University of Western Australia, says: ``Caster Semenya obviously identifies as a woman, she believes she is a woman even though medically she may not fit into the neat model of what a woman's genes are like.''

As Hill suggests, if there's no hard evidence that Semenya has a biological advantage, she should be allowed to run with the sex she identifies with: female.

Meanwhile, the International Olympic Committee and the AIS won't comment on implications for Australian athletes until the IAAF makes a move, and the IAFF is sitting tight until November.
The hope is that when they do go public, Caster Semenya will be the first to know.