Testosterone
Testosterone is responsible for the development of the male reproductive system, alongside promoting muscle, bone, and hair growth. Both men and women possess the hormone, although males have eight times the level of females on average (Sandnes, 2004).
In a nutshell, testosterone is what makes you horny. Research has shown that even after castration, rats administered with the hormone experience a remarkable return of sex drive. Further studies on humans have shown that the increase in androgen receptors from higher levels of testosterone contribute to the increased libido. It’s also been shown that women with higher circulating levels of testosterone have more sexual thoughts, a greater desire for sex, and higher mean levels of sexual activity (Morris, 1987).
Men’s testosterone levels are sensitive to the ovulation cycle of a woman. If you’re a guy, you might have experienced a seemingly random spike in attraction for a woman who you wouldn’t ordinarily see that way. The Ovulatory Shift hypothesis suggests that males are adapted to sense when a woman is most fertile and experience a subsequent rise in the hormone. In other words, you may find yourself highly aroused around certain women without knowing why, thanks to the evolution of Testosterone in males.
