Even if the science behind this claim is true (which I have no idea), it seems untenable to me to predict biological developments hundreds of thousands of years into the future. Fer cryin’ out loud, the whole human race could be extinct by then. The only reliable predictions (IMHO) on that time scale are things like star life cycles.
John Varley, for that matter. The short stories in “In the Hall of the Martian Kings” has a possible future in which sex-changes are common, routine and affordable. (And also bio-surgery that allows humans to survive, with the aid of some exotic cyber-implants, otherwise unprotected on Mercury, Venus, the Moon, and deep space, for a start.)
…On t’other hand, maybe most of us are quite happy with our bio-gender. ::shrug::
And of course this gets into sex ratios as well. Why do most species have approximately 50-50 ratios of males to females, when it might seem that the species could produce almost twice as many offspring if you had many more females than males?
The answer is that sex ratios are under genetic control, but that 50-50 is a stable equilibrium. If the ratio were 10% males and 90% females, then a typical male would have 9 times as many offspring as a typical female, and vice versa for 90% female/10% male. That means that having a gene that makes you male would be nine times as likely to be passed on as a gene that makes you female. In practice you almost never see such skewed sex ratios because the advantage to being the minority sex quickly overwhelms any other countervailing selection.
Please read the sticky on desriptive thread titles. Damn, I thought this was a thread about getting high. 