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.     
It is further noticed that Sustanon is also effective when relatively low doses are given to well advanced athletes. It is interesting to note that when Sustanon is given to athletes who have already used this compound in the same or lower doses, it leads to similar good results as during the previous intake. Sustanon is usually injected at least once a week, which can be stretched up to 10 days. The dosage in bodybuilding and powerlifting ranges from 250 mg every 14 days up to 1000 mg or more per day. Since such high dosages are not recommended-and fortunately are also not taken in most cases the rule is 250-1000 mg/week. A dosage of 500 mg/week is completely sufficient for most, and can often be reduced to 250-mg/ week by combining Sustanon with an oral steroid. Sustanon is well tolerated as a basic steroid during treatment which stimulates the regeneration, gives the athlete a sufficient "kick" for intense training units, and next to the already mentioned advantage of rapid strength increase and solid muscle gain distinguishes itself also by its compatibility. In order to gain mass fast Sustanon is often combined with Deca-Durabolin, Dianabol or Anadrol while athletes who are more into quality prefer combining it with Parabolan, Winstrol, Oxandrolone or Primobolan.
Testosterone enanthate ( USAN , BAN ) (brand names Delatestryl , Testostroval , Testro LA , Andro LA , Durathate , Everone , Testrin , Andropository ), or testosterone heptanoate , is an androgen and anabolic steroid and a testosterone ester .    Along with testosterone cypionate and testosterone propionate , it is one of the most widely used testosterone esters.  Testosterone enanthate was first introduced in 1952.  Administered via intramuscular injection , it is the most widely used form of testosterone in androgen replacement therapy .