Hormonal Theories

Hormonal theories of sex differences argue that men and women dif fer not because of the external social environment but, rather, because the sexes have dif ferent underlying hormones. It is these physiological dif ferences, not differential social treatment, that causes boys and girls to diver ge over development. Thus, some studies have sought to identify links between hormones such as testosterone (present in greater amounts in men) and sex-linked behavior .

There is some evidence that hormonal influences on sex di ferences begin in utero. The hormonal bath that the developing fetus is exposed to, for example, might affect both the or ganization of the brain and consequently the gendered interests and activities of the individual. Some of the best evidence for this comes from a condition called congenital adrenal hyperplasia (CAH), in which the female fetus has an over-active adrenal gland. This results in the female being hormonally masculinized. Young girls with CAH show a marked preference for "male" toys, such as Lincoln logs and trucks (Berenbaum & Snyder, 1995). As adults, CAH females show superiority in traditionally masculine cognitive skills, such as spatial rotation ability and throwing accuracy, as well as preferring traditionally masculine occupations (Kimura, 2002). These findings suggest that fetal exposure to hormones can have lasting e fects on gender -linked interests and abilities, although further research is needed in this area.

Men and women do differ in their levels of circulating hormones. Women's level of circulating testosterone typically falls between 200 and 400 picograms per milliliter of blood at the lowest part of the menstrual cycle and between 285 and 440 at the highest part of the menstrual cycle (just prior to ovulation) (Hoyenga & Hoyenga, 1993). Men, in contrast, have circulating testosterone levels ranging from 5,140 to 6,460 picograms per milliliter of blood. Following puberty , there is literally no overlap between the sexes in their levels of circulating testosterone. Men typically show more than 10 times the levels of women.

These sex dif ferences in circulating testosterone have been linked with some of the traditional sex dif ferences found in behavior, such as aggression, dominance, and career choice. In women, for example, high levels of testosterone are linked with pursuing a more masculine career and having greater success within the chosen career (Hoyenga & Hoyenga, 1993). In lesbian women, testosterone has been associated with erotic role identification, with mor "masculine" lesbian partners having higher levels of testosterone than more "feminine" partners (Singh et al., 1999). Higher testosterone levels are associated with greater dominance and aggressiveness in both sexes. For example, in one study, female prison inmates who had more frequent disciplinary infractions also had higher testosterone (Dabbs & Har grove, 1997). And Dabbs and colleagues (Dabbs, Hargrove, & Heusel, 1996) found that members of college fraternities who were more rambunctious tended to have higher average levels of testosterone than those in fraternities who were more well-behaved.

Sexual desire has also been linked to levels of circulating testosterone. Women's testosterone levels peak just prior to ovulation. Interestingly , women report a peak in their sexual desire at precisely the same time. At this peak, women report more female-initiated sexual intercourse and more desire for sexual intercourse (Sherwin, 1988). Men with relatively high testosterone levels also report an increased level of sexual motivation (Dabbs & Dabbs, 2000). And weekly and seasonal changes in testosterone are correlated with parallel changes in sexual motivation (Hoyenga & Hoyenga, 1993).

These findings do not prove that the di ferences between men and women in sexuality , dominance, aggression, and career choices result from dif ferences between the sexes in testosterone levels.

Testosterone is associated with dominance and aggressiveness, as well as with the massive buildup of muscular tissue. Here U.S. Olympic weightlifter Tim McRae rejoices after setting a new U.S. record in the snatch of 145 Kg, a feat no woman in his weight class is likely to ever match. Olympic athletes are tested to make sure their testosterone levels are within normal ranges for their sex.

Testosterone is associated with dominance and aggressiveness, as well as with the massive buildup of muscular tissue. Here U.S. Olympic weightlifter Tim McRae rejoices after setting a new U.S. record in the snatch of 145 Kg, a feat no woman in his weight class is likely to ever match. Olympic athletes are tested to make sure their testosterone levels are within normal ranges for their sex.

Correlation does not mean causation. Indeed, there is some evidence in nonhuman primates that rises in testosterone levels follow rises in status and dominance within the group, rather than lead to them (Sapolsky, 1987). Furthermore, sexual arousal itself can result in an increase in testosterone level (Hoyenga & Hoyenga, 1993). A study on sports fans found that those whose team had just won an event had higher levels of testosterone than those fans whose team had just lost (Bernhardt et al., 1998). These results suggest that the link between hormones and behavior is bidirectional. Higher testosterone may result from, as well as cause, behavior changes.

An additional limitation of hormonal theories of sex dif ferences in personality is one shared with socialization theories—namely , neither of these theories identifie the origins of the dif ferences. Precisely why do men and women dif fer so dramatically in their levels of circulating testosterone? Is this merely an incidental ef fect of being male versus being female? Or is there a systematic process that causes men and women to dif fer in testosterone precisely because testosterone dif ferences lead to behavioral differences in dominance and sexuality? One theoretical perspective that argues for this possibility is evolutionary psychology .

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  • ansegar
    What is hormonal theory?
    7 months ago

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