Testosterone is a steroid hormone from the androgen group and is found in mammals, reptiles, birds, and other vertebrates.
In men, testosterone plays a key role in the development of male reproductive tissues such as the testis and prostate as well as promoting secondary sexual characteristics such as increased muscle, bone mass, and the growth of body hair.
Testosterone makes a woman love a man. When testosterone from semen meets the cervix after intercourse, females then have an elevation of this hormone as well as a spike in oxytocin. This stimulates feelings of desire, love, and maternal care. However, there was no correlation between high testosterone levels and a greater sexual assertiveness for either sex.
Plenty of studies conducted on human males show that normal or high levels of testosterone were linked to more sexual activity. Also, heterosexual men had higher than normal testosterone levels after engaging in sexual activity after brief interaction with women. This elevation of the sex hormone was correlated to the intensity of courtship behavior.