High school biology covers this. There is an observed increase in competitiveness commensurate with an increase in testosterone, within sexual arousal responses. see reference [46] within the testosterone wiki for whatever that is worth.
That's a reference from 1986. We now know that the increase in aggression is due to higher levels of estradiol due to aromatization of testosterone to estradiol. It's pretty well known that if you give a group of men exogeneous testosterone and an aromatase inhibitor, they will report being calmer and more relaxed.
