An eight-ounce oyster has 18 grams of protein — making gains easy while upping your t-levels. Oysters are rich in zinc, a t-boosting mineral. From food, you get about 10 milligrams of zinc each day, but the body only absorbs 2-3 milligrams of it — putting you at risk for a deficiency. The common cold is actually a symptom of low zinc levels along with a low sex-drive, which is an indication of low-t levels. When low zinc levels are present, the pituitary gland limits the release of the luteinizing and follicle stimulating hormones; they are responsible for triggering T production in the testes. This then decrease the amount of androgen binding sites and free testosterone in the blood stream.
The second theory is similar and is known as "evolutionary neuroandrogenic (ENA) theory of male aggression".   Testosterone and other androgens have evolved to masculinize a brain in order to be competitive even to the point of risking harm to the person and others. By doing so, individuals with masculinized brains as a result of pre-natal and adult life testosterone and androgens enhance their resource acquiring abilities in order to survive, attract and copulate with mates as much as possible.  The masculinization of the brain is not just mediated by testosterone levels at the adult stage, but also testosterone exposure in the womb as a fetus. Higher pre-natal testosterone indicated by a low digit ratio as well as adult testosterone levels increased risk of fouls or aggression among male players in a soccer game.  Studies have also found higher pre-natal testosterone or lower digit ratio to be correlated with higher aggression in males.