Researchers have found that the hormone estrogen is responsible for the way males behave in an unfeminine way from being a boy to being a grown man.
Laboratory testing of mice showed that an estrogen receptor in the hypothalamus is responsible of defeminization or removal of feminine traits from man. This starts acting even before the birth of the individual. This process seems to be the main neurological factor that distinguishes the male from the female. Only estrogen and estrogen receptor affect the male fetus as the females are exposed to this hormone after birth, only when they reach puberty. This is because only a fully-grown ovary can secrete estrogen and this does not happen before puberty.
A neonatal male is exposed to the steroid estradiol, which is released from the tests and is a form of the estrogen. Estradiol attaches to the estrogen receptor ERb and this together regulates the genetic composition that forms the main genetic pattern of the adult behavior.
The study is published in the March issue of Proceedings of the National Academies of Sciences. The new role for estrogen receptor may pave way for further research into sex-specific diseases, behavioral areas of aggression, depression etc. and many others.
Reference: Proceedings of the National Academies of Sciences, March 2005