Yamanaka would avenge her only loss at Jewels 7th Ring when she defeated Hitomi Akano by split decision on March 19, 2010 ( 2010-03-19 ) .   Unlike their first open-weight match, this match was contracted at 143 lb (65 kg) and, for the first time in her career, Yamanaka had to cut weight;  cutting more than 20 lbs.  On May 23, 2010 ( 2010-05-23 ) , Yamanaka defeated Atsuko Emoto by unanimous decision at Jewels 8th Ring .   Emoto announced her retirement after the fight.
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.