Man labioscrotal folds into the scrotum. Another significant hormone in sexual differentiation is the anti-Müllerian hormone, which inhibits development of the Müllerian ducts. In general, men suffer from many of the same illnesses as women. In comparison to women, men suffer from slightly more illnesses. Male life expectancy is slightly lower than female life expectancy, although the difference has narrowed in recent years. For males during puberty, testosterone, along with gonadotropins released by the pituitary gland, stimulates spermatogenesis, along with the full sexual distinction of a human male from a human female, while women are acted upon by estrogens and progesterone
Sexual selection in mammals neck length is not correlated to increases in other parts of the body, which would be expected from foraging selection, so sexual selection may be a more satisfactory explanation. Studies have failed to resolve the causes involved: perhaps the neck was a result of both or other forces. Precopulatory mechanisms determine who father an offspring prior to sex. Male-male competition is the biggest precopulatory mechanism in mammals. Sexual dimorphism is a result of male-male competition that is easily seen in species. Male-male competition to copulate with the opposite sex is often seen in mammals. African elephants strongly promote male-male competition.