Physiological and Hormonal Sex Differences

Hormonal differences between the sexes in humans, as in other mammals, are so pervasive and systematic, and are the mediators for so many other differences, that they are sometimes incorrectly cited as the biological causes of sex differences. It is clear, however, that these mediators have evolved to differ between the sexes, just as in other species, and specifics vary. Sex hormones organize a variety of sexually dimorphic behaviors, from aggression to reproductive behavior (see reviews by Kimura [1999] and Wizemann and Pardue [2001] for hormonal details, and by Low [2000], Mealey [2000] and Geary [1998] for behavioral, evolutionary, and ecological comparisons). Although both sexes have both androgenic and estrogenic compounds, they do so in differing degrees. In general, the baseline condition hormonally (and in resulting embry-ological development) is "female," and androgens are required to masculinize both physical and behavioral traits. The sex chromosomes impart important information. For example, it has long been clear that the Y chromosome is necessary for the development of testes; this is accomplished by testicular differentiating hormone (TDF) (Vilain & McCabe, 1998). As with several other kinds of sexual dimorphisms, much of what we know comes from studying individuals with deficiencies or defects (below).

Pregnancy And Childbirth

Pregnancy And Childbirth

If Pregnancy Is Something That Frightens You, It's Time To Convert Your Fear Into Joy. Ready To Give Birth To A Child? Is The New Status Hitting Your State Of Mind? Are You Still Scared To Undergo All The Pain That Your Best Friend Underwent Just A Few Days Back? Not Convinced With The Answers Given By The Experts?

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