[gambling8nt]

Half a century--two human generations--is not nearly enough time for evolutionary pressures to have the sort of effect you are talking about. Least of all in a society of abundance in which the majority of members reproduce.

Instead, I'd suggest you look at the various changing environmental factors for an explanation of these phenomena: BPA in plastics (http://en.wikipedia.org/wiki/Bisphenol_A), the growing use of soy in human diets (with its attendant phyto-estrogens), and the growing quantities of synthetic human estrogen in the environment (already known to have effects on fish, see for instance http://www.seattlepi.com/local/124939_estrogen04.html).

[FlorinAndrei]

Sure, phyto- and xeno-estrogens are strong suspects in this case. But here's another data point:

Measure the testosterone level in your bloodstream.

Then for a few weeks start doing heavy squats (weight lifting) every other day, go car racing, skydiving, etc.

Now measure T again. See the difference?

There are all sorts of things like that. The bottom line is, the more secure the environment, the less the need for men to be "men".

Also, I was not implying that the new evolutionary pressures have already made changes, I was just saying the changes are being made now - but how long before they will become visible, I have no idea. Probably not tomorrow.

[gambling8nt]

I agree that lack of physical activity is another likely factor for changing hormone levels and their secondary effects.

However, I know of no reason to think that these changes are heritable, or that naturally low T is actually a reproductive advantage in our society. (Indeed, given that we have inverted the more typical historical trend of the wealthy out-reproducing the less wealthy, and the selection of low-T for wealth here asserted, one might expect that this society actually reflects reproductive pressure against low-T, rather than in favor of it.)