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Human Sex Differences (human + sex_difference)
Selected AbstractsHuman sex differences in d -amphetamine self-administrationADDICTION, Issue 4 2010Andrea R. Vansickel ABSTRACT Women and men may respond differently to the effects of stimulants such as amphetamine and cocaine. Aim In order to assess potential sex differences in the reinforcing effects of d -amphetamine, a retrospective-analysis was conducted on data collected from three studies that employed similar d -amphetamine self-administration procedures and used identical subject-rated drug-effect measures. Methods Data from 10 women and 15 men were included in the analysis. In all studies, participants sampled placebo, low (8,10 mg) or high (16,20 mg) dose oral d -amphetamine. Following sampling sessions, participants worked for capsules containing one eighth of the previously sampled dose on a modified progressive-ratio schedule of reinforcement. We hypothesized that women and men would be differentially sensitive to the reinforcing effects of d -amphetamine. A two-way mixed-model analysis of variance (sex and dose) and planned comparisons were used in the statistical analyses. Results The low dose of d -amphetamine functioned as a reinforcer in women, but not men, whereas the high dose of d -amphetamine functioned as a reinforcer in men, but not women. Men self-administered significantly more capsules under the high dose condition than women. Conclusion The results of this study suggest that men are more sensitive to the reinforcing effects of a high dose of d -amphetamine than women. Future research is needed that determines prospectively the reinforcing effects of weight-adjusted doses of d -amphetamine in women and men while controlling for menstrual cycle phase. [source] Turner syndrome and the evolution of human sexual dimorphismEVOLUTIONARY APPLICATIONS (ELECTRONIC), Issue 3 2008Bernard Crespi Abstract Turner syndrome is caused by loss of all or part of an X chromosome in females. A series of recent studies has characterized phenotypic differences between Turner females retaining the intact maternally inherited versus paternally inherited X chromosome, which have been interpreted as evidence for effects of X-linked imprinted genes. In this study I demonstrate that the differences between Turner females with a maternal X and a paternal X broadly parallel the differences between males and normal females for a large suite of traits, including lipid profile and visceral fat, response to growth hormone, sensorineural hearing loss, congenital heart and kidney malformations, neuroanatomy (sizes of the cerebellum, hippocampus, caudate nuclei and superior temporal gyrus), and aspects of cognition. This pattern indicates that diverse aspects of human sex differences are mediated in part by X-linked genes, via genomic imprinting of such genes, higher rates of mosaicism in Turner females with an intact X chromosome of paternal origin, karyotypic differences between Turner females with a maternal versus paternal X chromosome, or some combination of these phenomena. Determining the relative contributions of genomic imprinting, karyotype and mosaicism to variation in Turner syndrome phenotypes has important implications for both clinical treatment of individuals with this syndrome, and hypotheses for the evolution and development of human sexual dimorphism. [source] Sexual Differentiation of Behaviour in Monkeys: Role of Prenatal HormonesJOURNAL OF NEUROENDOCRINOLOGY, Issue 4 2009K. Wallen The theoretical debate over the relative contributions of nature and nurture to the sexual differentiation of behaviour has increasingly moved towards an interactionist explanation that requires both influences. In practice, however, nature and nurture have often been seen as separable, influencing human clinical sex assignment decisions, sometimes with disastrous consequences. Decisions about the sex assignment of children born with intersex conditions have been based almost exclusively on the appearance of the genitals and how other's reactions to the gender role of the assigned sex affect individual gender socialisation. Effects of the social environment and gender expectations in human cultures are ubiquitous, overshadowing the potential underlying biological contributions in favour of the more observable social influences. Recent work in nonhuman primates showing behavioural sex differences paralleling human sex differences, including toy preferences, suggests that less easily observed biological factors also influence behavioural sexual differentiation in both monkeys and humans. We review research, including Robert W. Goy's pioneering work with rhesus monkeys, which manipulated prenatal hormones at different gestation times and demonstrated that genital anatomy and specific behaviours are independently sexually differentiated. Such studies demonstrate that, for a variety of behaviours, including juvenile mounting and rough play, individuals can have the genitals of one sex but show the behaviour more typical of the other sex. We describe another case, infant distress vocalisations, where maternal responsiveness is best accounted for by the mother's response to the genital appearance of her offspring. Taken together, these studies demonstrate that sexual differentiation arises from complex interactions where anatomical and behavioural biases, produced by hormonal and other biological processes, are shaped by social experience into the behavioural sex differences that distinguish males and females. [source] Why men have shorter lives than women: Effects of resource availability, infectious disease, and senescenceAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2009A.P. Møller Senescence arises from age-specific deterioration of the soma as a consequence of optimization of life history, and such effects of senescence should appear when comparing species that differ in intensity of sexual selection, as well as when comparing, within a species, the two sexes that often differ in intensity of sexual selection. However, any extrinsic cause of mortality that reduces life expectancy will reduce the possibility of detecting sex-specific differences in senescence. We investigated geographical variation in human sex differences in longevity across 121 countries to test whether differences in sexual competition for limiting resources, reflecting intensity of sexual selection, affected sex differences in longevity. Men on average lived 5 years shorter than women. High rates of childhood morbidity and mortality reduced the sex difference in longevity, while increased overall longevity increased the sex difference in longevity. Increased resource availability estimated from gross domestic product per capita reduced the sex difference in longevity, accounting for 10% of the variance, while there was no additional effect of income inequality as reflected by the Gini coefficient. In a separate analysis of sex differences in longevity among the states of the US, there was a strong effect of the Gini coefficient on sex difference in longevity, with the negative effect on male longevity being stronger than that on female longevity. In contrast, there was only a marginal effect of average household income. Thus, there was evidence of increased competition for resources contributing to increased sex differences in longevity within a single nation. Am. J. Hum. Biol., 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||