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.     
The ThinPrep® PapTest TM (Cytyc Corp., Marlborough, MA), and SurePath (TriPath Imaging Inc., Burlington, NC) are automated liquid-based thin layer slide preparation techniques. With the ThinPrep System, a conventional Pap smear is not performed. Using a spatula and a brush or a cervical broom, the cervical area is sampled and the devices are rinsed in a fixative solution. The slide is then automatically made in the laboratory, which decreases the possibility of air-drying artifacts. It is then stained and read by a technician or a cytopathologist. SurePath (formerly known as AutoCyte PREP) is another liquid-based thin-layer sample preparation system that uses centrifugation to separate cells from obscuring material, and automatically prepares and stains cytology slides.