Testosterone boosts skepticism

Two words - Anabolic Clinic.

...The study also adds support to the idea that testosterone influences human behavior, not necessarily by increasing aggression, but by motivating people to raise their status in the social hierarchy or become more socially dominant.

Testosterone might boost social watchfulness, making those who are most trusting a little more vigilant and better prepared for competition over rank and resources, the researchers say.

"To be more successful in competition you have to be sharp ... you have to be also socially sharp," researcher Jack van Honk of the University of Cape Town, South Africa told LiveScience. "And to be socially sharp it's not smart to trust people you don't know," he said.

Yes, it is for women, too.