In small-brained mammals, maternalism places a severe restriction on sexual activity. The consequent sparsity of oestrous, sexually receptive females imposes a rigorous competitive reproductive strategy in males, with the burden being left to maleʼs ability to find oestrous females. This has resulted in a marked sex difference in the chemosensory system. With the evolutionary expansion of the neocortex, reproductive strategies depend far more on intelligent behaviour determinants than on hormonal determinants. Differences in sexual behaviour depend a great deal on social structure, social learning and the deployment of intelligent behavioral strategies.

Androgens, the male sex hormones, play an essential role in male sexual differentiation and development. Testosterone represents a pivotal hormone in regulating male sexual function, acting both at central and peripheral level. In women androgens are also critical for genital structure and function (clitoris, frenuluae, labia, corpora spongiosa, vestibular glands, vagina). Several studies have shown that many women have low values of androgens and many women have sexual dysfunctions, partly due to abnormally low androgens blood levels.

It is a generally well known fact that female sexual dysfunction is also strictly correlated to the male sexual health. Many female partners of men with erectile dysfunction or premature ejaculation report having some form of sexual disorder, mostly orgasmic problems and decreased sexual desire.

Many authors have demonstrated that the recovery of erectile function after PDE5 therapy can induce significant improvements even in partners’ratings of sexual function in most domains, including arousal, pleasure, and orgasm. In these analysis, the partners tend to report greater overall satisfaction with the sexual experience than the patients. It may be that women place less emphasis on the erection and are satisfied if the overall sexual encounter was emotionally gratifying.

Sexual activity arises from the overlapping of three different domains: biological, psychological and relational; so a multidisciplinary approach is required to face up sexual problems in the couple. Therefore, sexual medicine must cover four dimensions: the promotional dimension (increases awareness and helps individuals have a healthy and fulfilling sex life); the preventive dimension (counselling); the curative dimension (clinical treatment of specific sexual disorders) and the rehabilitative dimension (helps patients regain sexual health).