Well, they're sterile too. That's certainly an evolutionary disadvantage.
https://en.wikipedia.org/wiki/5α-Reductase_deficiency#Fertil...
It's a good book. I recommend it. I guess my point is that sometimes when something is different Now, it's hard to grasp it's significance and pros and cons because maybe our viewpoint is skewed to our current perceptions (which is a theme throughout the book, it has alot of time travel).