Wouter,

Population decreases happen periodically. Traditionally they are caused by disasters, diseases and wars. Of those, war is the only people-killer that increased its "efficiency".

Birth rates depend a lot on different hormone balances between women and men and also on the so called "cultural" factor - in fact, the two are very closely linked. Most sex-related aspects of cultures are caused and regulated by hormones.

As a species, our reaction to the growing perception of the likeliness of a malthusian chrisis is a change in cultural habits and hormone levels. We are actually passing through an important modification/adaptation of human behavior (= hormone balance = cultural change) to compensate for the new survival conditions (= environment) we are living. I would expect men and women to modify their hormone balance and "cultural" behavior more or less automatically while the available space and natural resources shrink.

The changes on ourselves are one of the causes of the "large changes in Western culture", more then a consequence of them. If the changes become more pronounced, women and men will continue to become more equal, especially in hormone balance, for it is the most efficient birth control system nature provided to our species.

Considering that the current population and the use of Earth´s resources are unprecedent, it is also reasonable to expect the hormonal and cultural changes to be the greatests ever - and this is a good thing if we consider that the main alternative is global war.

The hormone balance-cultural development link more or less explains the sexual behavior of "decadent" cultures in history. Rome, for instance. It also explains the polarized acceptance or rejection of homossexualism during contractions or expansions of the population.

Conlusion: women are already changing the way their look at life and sport and we should expect this change to continue in the same direction for a while. Actually, I HOPE it goes this way, because I see it as a key part of the peaceful solution for the upcoming Malthusian chrisis - possibly the greatest challenge humanity ever faced.

Take care,