It is my hypothesis that human evolution is driven by high testosterone (Rivista di Biologia / Biology Forum 2001; 94: 345-362). The characteristic which started this is an increase in female testosterone. This exposes the fetus to increased testosterone and begins the characteristics we call human.

I suggest that periodically female testosterone increases and when this becomes excessive, the increased testosterone causes some adverse phenomena, including brain changes which produce homosexuality. I think this is occurring now in the populations, such as increasing homosexuality, obesity, diabetes, metabolic syndrome, etc.

This applies to this hypothesis this way: the "curious patterns" mentioned may all be explained by high testosterone females. This increase in female testosterone will appear in well fed populations; food does not cause this, food simply accelerates it. A number of populations are now well fed so we see this in a number of populations. The connection demonstrated by these "curious patterns" is inheritance of high testosterone in related women. (If interested further: <link> ).

What about the reports of decreased testosterone in men over the last generation, sometimes linked to environmental factors?

I have described the effects of increasing testosterone in women on their fetuses. If environmental toxins, such as phthalates, reduce testosterone in pregnant women, then this could reduce the incidence of homosexuality, according to my hypothesis. However, reports appear to suggest that phthalates affect testosterone levels withing male fetuses, not pregnant mothers. So, if I am correct, phthalates may affect later, sexual drive and anatomy, which would affect both heterosexual and homosexual males in a similar manner, without affecting sexual orientation.

very helpful. thanks for the reply.