I like this comment from the Guardian article:
To put this into some context.
The first male to run a mile in under 4 minutes was Roger Bannister in 1954. Nearly 62 years ago.
The first female to run a mile in under 4 minutes was... ....well, there aren't any. It hasn't been done. No woman has ever run a mile in under 4 minutes.
Despite all the science, the modern methods of training, applying all we know about nutrition, the current women's world record for the mile is 4:12.56 set by Svetlana Masterkova in 1996.
Let's put that into some context: how does that current record compare to the men's?
The closest time is the men's world record set by Norman Taber - 4:12.6
He set this record in the year 1915 so Masterkova's time is on par with a guy who probably ran in a flat cap and hobnail boots.
And it gets worse. Let's compare Masterkova's record with the current men's world record:
The current men's world record is...drumroll... 3:43.13 set by Moroccan, Hicham El Guerrouj in 1999.
That's nearly 30 fucking seconds of a difference. THIRTY SECONDS.
These aren't small differences. These are yawning, unbridgeable chasms of physiology and biomechanics. It's apparent in every single event and it scales by distance.
1500m Men: 3:26.00
1500m Women: 3:50.07
24 seconds of a difference
10000m Men: 26:17.53
10000m Women:29:31.78
Over three minutes of a difference
Men's Marathon: 2:02:57
Women's Marathon: 2:15:25
Nearly 13 minutes - thirteen fucking minutes
Even if it were possible to police the hormone level and rely on athletes to not attempt to flaunt the rules (and how likely is that?), these changes do not affect biomechanics, they do not affect lung capacity and they absolutely will not level the playing field. You're basically looking at biologically born women never winning a medal in anything ever again.