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As States Consider Restrictions On Trans Athletes, What Does The Science Say?


Now we want to tell you about a fierce, often emotional debate taking place in many legislatures across the country. It's about transgender athletes in sports. Now, most of these bills are aimed at limiting or prohibiting transgender athletes from competing in women's sports. Right now, about 35 such bills are being considered in 20 states, according to the LGBT rights group Human Rights Campaign. Just days ago, Mississippi Governor Tate Reeves signed one such law, which is scheduled to go into effect later this year.

Now, supporters of these bills say they are necessary to reduce what they think is an inherent competitive advantage of transgender athletes who identify as female, which could even make competition in some sports unsafe for other girls and women. But advocacy groups like the ACLU say that is false, that these laws are discriminatory and really just another culture war bugaboo of the right. They also argue that if allowed to stand, they will open the door to humiliating treatment of many women and girls just because they don't look a certain way.

Right now, we want to take a step back from the culture war aspect of this and learn what the science says. For that, we turn to Dr. Eric Vilain. He holds an MD and a PhD. He is a pediatrician and geneticist at Children's National Hospital here in Washington, D.C. He has studied sex differences throughout his career, and he's also advised the International Olympic Committee on these issues. And he is with us now. Dr. Eric Vilain, thank you so much for joining us.

ERIC VILAIN: I'm glad to be here.

MARTIN: So before we jump in, I just want to say that I don't think everybody is necessarily familiar with the terms that we might use. So to get everybody on the same page, I'd like to ask you to quickly define some key terms as briefly as you can. What exactly do we mean when we say transgender? And what exactly do we mean when we say cisgender?

VILAIN: Transgender refers to individuals whose gender identity is different from their sex of birth, for example. And it's - they have typically transitioned from one gender to the other, hence the term trans. And cisgender is individuals who, by contrast, have not transitioned.

MARTIN: As we mentioned, supporters of these bills say they are meant to eliminate any competitive advantage that transgender athletes may have. But those who oppose these laws say transgender girls don't have an inherent advantage over cisgender girls. At least, they don't have an advantage that is any greater than the normal variation within a group. And so I'd like to ask you if there is data on this, and what does it show?

VILAIN: Yes, we know that men have on average an advantage in performance in athletics of about 10 to 12% over women, which the sports authorities have attributed to differences in levels of a male hormone called testosterone. The question is whether there is in real life, during actual competitions, an advantage of performance linked to this male hormone and whether trans athletes are systematically winning all competitions.

The answer to this latter question - are trans athletes winning everything? - is simple. That's not the case. And higher levels of the male hormone testosterone are associated with better performance only in a very small number of athletic disciplines - 400 meters, 800 meters, hammer throw, pole vault. And it certainly does not explain the whole 10% difference.

And lastly, I would say that every sport requires different talents and anatomies for success. So I think we should focus on celebrating this diversity rather than focusing on relative notions of fairness. For example, the body of a marathon runner is extremely different than the body of a shotput champion. And a trans woman athlete may have some advantage on the basketball field because of her height but would be at a disadvantage in gymnastics.

So it's complicated. And more and more, many trans women athletes, for example, will take gender-affirming hormones, which will reduce their muscle mass and red blood cells, which carry the oxygen necessary for better performance. And that will also reduce the speed, the strength and the endurance.

MARTIN: At the high school level, are transgender athletes taking those hormone-suppressing drugs?

VILAIN: So at a high school level, many trans youth do delay their puberty, which means that even if they are not taking these gender-affirming hormones, their natural puberty in their biological sex is not happening, therefore resulting in a delay and an absence of an effect on muscle mass, at least for the male-to-female situation. So the supposed advantage of muscle mass and red blood cells because of testosterone becomes moot in middle and often high school competitions when there have been puberty blockers involved.

MARTIN: One of the groups that has come out against these types of laws is the National Women's Law Center. They wrote a brief against a bill in Idaho that seeks to ban transgender girls from participating in youth female sports. And in it, they write, quote, "the law allows anyone for any reason to question whether a student athlete is a woman or girl. And then the student has to verify her gender by undergoing invasive testing, which could include a gynecological exam, blood work or chromosome testing." And one of the plaintiffs in this is - was a plaintiff named Jane Doe, who was a cisgender female athlete, but she doesn't normally wear skirts or dresses and has an athletic build. And they're saying that under a law like this, somebody could just ask or insist that this athlete undergo one of these exams to prove her gender, that that's inherently harmful and serves no legitimate purpose. What do you say to that?

VILAIN: You know, it's interesting because in the field of sports, there's a long history of discrimination that targets women that look different. Again, the science of whether testosterone in real life is actually providing an advantage in competition is not clearly established. But more disturbingly is that all these rules at the elite level have affected women - not all women, but women with a Y chromosome. And often, it's triggered by women who look different. So I'm a little disturbed to hear that these issues at the elite level are now reaching the middle and high schools and colleges.

MARTIN: As we said, these - there are a number of these bills making their way through state legislatures. Moving forward, how would you like people to think about this debate? Is there something you would encourage people to think about? Or...

VILAIN: I would encourage parents and people interested in sports to look at all the sides of the issue and not being fixated on the sole issue of gender. There are so many different attributes for an athlete that make them so diverse, so interesting, so different. Some will be good at one sport. Some will be good at other sports. And we should just celebrate this diversity.

MARTIN: That is Dr. Eric Vilain. He's a pediatrician and geneticist at Children's National Hospital. He's been an adviser both to the NCAA and the International Olympic Committee. Dr. Vilain, thank you so much for being with us and sharing your expertise.

VILAIN: You're very welcome.

(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright NPR.