Homosexual mating preferences from an evolutionary perspective: sexual selection theory revisited.

Studies in evolutionary psychology and sexual selection theory show that heterosexual men prefer younger mating partners than heterosexual women in order to ensure reproductive success. However, previous research has generally not examined differences in mating preferences as a function of sexual orientation or the type of relationship sought in naturalistic settings. Given that homosexual men seek partners for reasons other than procreation, they may exhibit different mating preferences than their heterosexual counterparts. Moreover, mating preferences may show important differences depending on whether an individual is seeking a long-term versus a short-term relationship. The purpose of the present study was to examine these issues by comparing partner preferences in terms of age and relationship type between homosexual and heterosexual men placing internet personal advertisements. Participants included 439 homosexual and 365 heterosexual men who placed internet ads in the U.S. or Canada. Ads were coded for the participant's age, relationship type (longer-term or short-term sexual encounter) sought, and partner age preferences. Significantly more homosexual than heterosexual men sought sexual encounters, although men (regardless of sexual orientation) seeking sexual encounters preferred a significantly wider age range of partners than men seeking longer-term relationships. These findings suggest that partner preferences are independent of evolutionary drives to procreate, since both types of men preferred similar ages in their partners. In addition, they highlight the importance of examining relationship type in evolutionary studies of mating preferences, as men's partner preferences show important differences depending upon the type of relationship sought.

Puberty moderates genetic influences on disordered eating.

BACKGROUND: Previous research suggests that genetic influences on disordered eating may be greater in pubertal than pre-pubertal girls. Although these findings are consistent with pubertal activation of genetic influences on disordered eating, earlier studies were unable to directly test this hypothesis. The purpose of the present study therefore was to directly examine this possibility by investigating whether pubertal development moderates genetic influences on disordered eating. METHOD: Participants were 510 female adolescent twins from the Minnesota Twin Family Study. Disordered eating was measured with the Total Score of the Minnesota Eating Behavior Survey, while pubertal status was assessed with the Pubertal Development Scale. RESULTS: Consistent with our hypothesis, model-fitting indicated significant increases in genetic influence on disordered eating with advancing pubertal development. CONCLUSIONS: These findings suggest that puberty influences the expression of genes for disordered eating.

Preliminary evidence that gonadal hormones organize and activate disordered eating.

OBJECTIVE: Eating disorders are more common in females than in males. Gender differences may be due to organizational (i.e. prenatal) and activational (i.e. post-natal) gonadal hormone effects that influence sex differences in behavior. This preliminary set of studies examined these effects by investigating relationships between eating disorder symptoms, prenatal testosterone exposure, and adult levels of estrogen in women. METHOD: We examined organizational associations by investigating relationships between disordered eating and finger-length ratios, which are known to be somatic markers of prenatal testosterone exposure. Participants included 113 adult female twins drawn from the community. Disordered eating was assessed with the total score from the Minnesota Eating Behavior Survey (MEBS). Finger lengths were hand scored using a ruler and photocopies of both hands. We also investigated activational influences by examining associations between circulating levels of estradiol and disordered eating symptoms. Two independent samples of adult females (n's = 24 and 25) drawn from the community were used for this study. Disordered eating was again assessed with the MEBS total score, while saliva samples were used for assessing estradiol. RESULTS: Positive associations were found between disordered eating and both finger-length ratios and circulating estradiol levels. CONCLUSIONS: Findings suggest that lower levels of prenatal testosterone exposure and higher adult levels of estradiol are associated with increased eating disorder symptoms. We hypothesize that the relatively low level of testosterone before birth in females permits their brains to respond to estrogens at puberty, when the hormones activate the genes contributing to disordered eating in vulnerable girls.

Personality traits in women with anorexia nervosa: evidence for a treatment-seeking bias?

OBJECTIVE: Several personality traits have been associated with anorexia nervosa (AN) in treatment-seeking samples of patients. The current study used a population-based sample to compare the personality characteristics of women with AN who sought treatment versus those who did not. METHOD: Participants included 27 (14 treatment-seekers, 13 non-treatment-seekers) women with threshold or subthreshold AN and 273 (64 treatment seekers, 209 non-treatment seekers) comparison women from the Minnesota Twin Family Study. Personality was assessed with the higher-order factors and primary scales of the Multidimensional Personality Questionnaire (MPQ). RESULTS: Non-treatment-seeking women showed lower levels of negative emotionality, stress reaction, and alienation than treatment-seeking women. DISCUSSION: These results suggest that personality deviations may be overestimated in treatment-seeking samples.