Nature on Binary Sex

The science journal Nature has a nice piece on the science of sex. Claire Ainsworth writes that science does not support a strict nbinary view of sex. One scientist that she quotes says:

“I think there's much greater diversity within male or female, and there is certainly an area of overlap where some people can't easily define themselves within the binary structure,” says John Achermann, who studies sex development and endocrinology at University College London's Institute of Child Health.

The scientific abiguity can be problematic because many parts of society have been designed on a binary model of sex (for isntance, at ESPN Kate Fagan discusses the issue of "sex testing" as related to FIFA and the Women's World Cup):

These discoveries do not sit well in a world in which sex is still defined in binary terms. Few legal systems allow for any ambiguity in biological sex, and a person's legal rights and social status can be heavily influenced by whether their birth certificate says male or female.

“The main problem with a strong dichotomy is that there are intermediate cases that push the limits and ask us to figure out exactly where the dividing line is between males and females,” says Arthur Arnold at the University of California, Los Angeles, who studies biological sex differences. “And that's often a very difficult problem, because sex can be defined a number of ways.”

The article uses the term "disorders of sexual development" - DSDs - to refer to the condition of people who don't fall neatly into one or other of the male/female dchotomy. I am not a fan of this terminology as it suggests that people who fall outside of the binary have a "disorder" and thus are somehow abnormal. In contrast, what the science suggests is that what are called DSDs are in fact normal, but not typical.

Whatever terminology is used, the practical issues remain:

[I]f biologists continue to show that sex is a spectrum, then society and state will have to grapple with the consequences, and work out where and how to draw the line. Many transgender and intersex activists dream of a world where a person's sex or gender is irrelevant. Although some governments are moving in this direction, Greenberg is pessimistic about the prospects of realizing this dream — in the United States, at least. “I think to get rid of gender markers altogether or to allow a third, indeterminate marker, is going to be difficult.”

So if the law requires that a person is male or female, should that sex be assigned by anatomy, hormones, cells or chromosomes, and what should be done if they clash? “My feeling is that since there is not one biological parameter that takes over every other parameter, at the end of the day, gender identity seems to be the most reasonable parameter,” says Vilain. In other words, if you want to know whether someone is male or female, it may be best just to ask.

My draft paper - soon to be submitted - on "sex testing" proposes a policy solution to this issue based on scientific evidence that in some cases there is no clear binary of male and female. I'm still taking comments, please email me if you'd like to see the draft.