There are two theories on the role of testosterone in aggression and competition among males. The first one is the Challenge hypothesis which states that testosterone would increase during puberty thus facilitating reproductive and competitive behaviour which would include aggression as a result of evolution. Thus it is the challenge of competition in relation to testosterone among males of the species that facilitates aggression and violence. Studies conducted have found direct correlation between testosterone and dominance especially among the most violent criminals in prison who had the highest testosterone levels. The same research also found fathers (those outside competitive environments) had the lowest testosterone levels compared to other males. The second theory is also similar and is known as the evolutionary neuroandrogenic (ENA) theory of male aggression. Testosterone and other androgens have evolved to masculinize a brain in order to be competitive even as far as being a risk to harming 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. Thus, crime can be seen as an extreme form of adaptation to gain status and acquire more resources. Many other researchers have agreed with this and have stated that criminal behavior is an expression of inter-male competition in mating efforts and resource seeking since there is a huge correlation between criminals and fathering children at younger ages.