Testosterone is a steroid and male sex hormone (androgen). It plays a role in increased aggression, criminality, and competitive behaviour.
Many people associate testosterone with male sex drive, however increased testosterone shows no relation to increased male sexual desire (with the concurrent presence of high cortisol levels).
Dual hormone hypothesis[edit | edit source]
The fact that increased testosterone alone doesn't increase male sex drive provides some support for the dual hormone hypothesis. It is said some effects of testosterone become potentiated in the presence of lower levels of the stress hormone cortisol, and suppressed when higher levels of this hormone are present. Thus the two hormones interact with each other, in order to produce the effects commonly seen to be associated with Testosterone alone.