Wave Of Bills To Block Trans Athletes Has No Basis In Science, Researcher Says

Throughout the country, roughly 35 bills have been introduced by state legislators that would limit or prohibit transgender women from competing in women's athletics, according to the LGBTQ rights group Freedom for All Americans. That's up from only two in 2019.

The latest action in this push came last week, when Mississippi Governor Tate Reeves signed into law the "Mississippi Fairness Act." The law prohibits schools from allowing transgender female students to compete in female sports and cites "inherent differences between men and women" as one of the reasons to block these athletes from competition.

The often heated debates around these bills have centered on whether transgender women and girls have an unfair advantage over cisgender women — a term used for those who identify with the sex assigned to them at birth.

Proponents say the legislation is needed in order to maintain fairness in women's athletics by reducing what they believe is an inherent competitive edge of trans athletes who identify as female. Critics call that a false argument and say the proposals are being used as a way to discriminate against transgender Americans. These proposals, they say, also risk opening the door to humiliating treatment of women and girls who don't fit culturally-accepted notions of femininity.

Often missing from the culture-war aspect of the debate is a focus on the type of questions that Dr. Eric Vilain has spent much of his career researching. Vilain, a pediatrician and geneticist who studies sex differences in athletes, says there are no good faith reasons to limit transgender women's participation in sports, especially at the high school level. Vilain has advised both the International Olympic Committee and the NCAA, and says these laws generally aren't based in scientific evidence, but rather "target women who have either a different biology or ... simply look different."

Dr. Villain joined NPR's Michel Martin earlier this week for a discussion about the science surrounding trans athletes. Below are excerpts from that conversation, edited in parts for clarity and length.

Interview Highlights

Supporters of these bills say they are meant to eliminate any competitive advantage that transgender athletes may have. So I'd like to ask you if there is data on this and what does it show?

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. But 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 from the body of a shot put champion, and a transwoman 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.

In your view, because you have advised the NCAA on this as well as the International Olympic Committee, is there a reason to limit the participation of transgender athletes at the high school level or perhaps even at the collegiate level? Is there any good faith reason to do that?

I don't think so. First, I will say that there is a huge difference between elite sports and sports in schools. Sports in schools are supposed to be primarily about inclusivity, setting individual goals, collective goals and well-being. And it is not supposed to be about crushing the competition. But if we want to make it this way, then the rules still need to be inclusive, or at least not come up with arguments that are not based in science. So one of the major issues in school — and of course in the elite world — is that binary categories make it quite difficult to come up with reasonable eligibility regulations. And they do create a lot of frustrations. So one way out of this could be opening up categories. That would be a way to explore different ways, a path to do sports competitions, especially in schools. However, adding categories needs to be well thought out and done with equal access to benefits, such as scholarships. Otherwise, it would create categories of second class citizens, which is certainly not a good thing.

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, "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 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?

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.

You helped the NCAA shape their guidelines for the inclusion of transgender athletes in 2011. You also advise the International Olympic Committee on similar issues. What do you look at when determining what makes a certain sport fair, especially given an eye to both fairness and inclusivity?

If we want to think about fairness, we should look first at the principles of the Olympic charter. It says every individual must have the possibility of practicing sport without discrimination of any kind. And in the Olympic spirit, what's true for schools should be true for colleges and should be for the elite level. And there is really a long journey of athletes with gender variations that are facing increasing rulings that are often discriminatory and not based on science. And they should inspire us to consider the full complexity of interpretation of data and cherish our more treasured values, which I would say in science is evidence, and of course embrace inclusivity.

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