Gender Bender: How do you tell a man from a woman? The International Olympic Committee has decided to use testosterone levels to decide who can compete as a woman. But it’s not that simple: testosterone levels of elite athletes, both male and female, spread out over a range and overlap as seen in this scatter plot: http://goo.gl/YIKFQ
• Besides, there are no studies showing that athletes with higher testosterone compete better in sports. Neither is there evidence that response to hormone is the same between individuals. An extreme case is complete androgen insensitivity syndrome. These individuals are chromosomally XY, the normal makeup for men, but their bodies don’t respond to testosterone. So they develop female genitals, but have testes, not ovaries. South African powerhouse runner Caster Semenya is thought to be one such person. She was banned from competing and then, mysteriously, brought back this year (http://goo.gl/cGyIb).
• Half a century ago, the IOC subjected women athletes to “nude parades” before a panel of judges. After realizing that outward appearance can be confounding (as a result of adrenal gland abnormality, for example), they tested for Barr bodies, characteristic of XX chromosomes. But females can have a single X chromosome. This was followed by testing for the SRY gene thought to determine male gender (See my Men! Why U So SRY? post http://goo.gl/VPF0J). But the Atlanta Olympics revealed 8 female athletes who carried this gene, all of whom were eventually allowed to complete.
• Naturally high testosterone in women is a genetic trait, no different from having more efficient muscles or acromegaly (tallness). So why should some athletes be penalized for this particular trait? Clearly, the goal is to prevent unfair advantage in sports. But it’s complicated….