Was Spanish hurdler María José Martínez-Patiño a male or female athlete? If science can't answer such a basic biological question as that, how can it determine if Lance Armstrong took performance-enhancing drugs? Yet the answer is sometimes cloudy. 

Males and females compete in different categories because men are biologically different. If men competed against women in many events, the participation of women would be scant because men would hold win all of the events and hold most of the records.  Martínez-Patiño
was a successful hurdler in the Spanish nationals but a persistent rumor - invoked again and again by female competitors - turned out to be true; Martínez-Patiño
had a Y chromosome, which is what makes a male a male. Yet defenders noted that the athlete has androgen insensitivity syndrome, or CAIS, which prevented her body from responding properly to testosterone and caused her to develop as a woman. She was reinstated for competition and genetic testing stopped being mandatory in 1999.

María José Martínez-Patiño, 1986. Link: Transas City

Testing had become necessary by the 1968 Olympics because the USSR was sending female athletes that many were convinced were men. They were female, it turned out, though with modern hindsight it is apparent they were chemically enhanced rather than men being put into female categories. By 2004, transgender athletes were even allowed to compete if they had been undergoing hormonal sex change treatment since at least 2002. In the last Olympics the testing itself became a little clearer; testosterone levels.

Using testosterone levels - 7 nanomoles per liter of blood and up for men while 3 is the top range for women - eliminates overlap. "We are not determining the gender in an individual. What we are talking about is athletic eligibility," Dr. Arne Ljungqvist, chairman of IOC's Medical Commission, told the Los Angeles Times.

In Archives of Sexual Behavior, the authors of a paper outline the cultural history of sports gender testing, through the controversial 2009 case of South African athlete Caster Semenya - born a woman but with no ovaries and undescended testicles - and onto the hyperandrogenism policy of 2011 which set standards around the upper hormonal limits allowed for athletes taking part in women's sporting events.

Is the system perfect? No, but officials have to draw a line somewhere or the reason for women having their own events would disappear. The authors of the paper, including María José Martínez-Patiño, want newer enhancements to cover those who have undergone sex-reassignment surgery and better privacy and confidentiality clauses and they say the initiation of assessments must also be revisited.

"The International Olympic Committee should continue to monitor and revise the hyperandrogenism policy with diligence in the near and distant future," says lead author Nathan Ha.