In the United States, public concern in sexual matters and stigmatization of sexual identities make people retreat into privacy. This sexual constraint makes people experience shame and guilt. According to Scheff, shaming is a cause of violence. In contrast, the German society shows less public concern and social opposition in the sexual-erotic domain. This sexuality allows privatization as ind...

BACKGROUND Globally, the proportion of youths has been steadily increasing, especially in Asia. This vulnerable population has limited exposure to sexual and reproductive health (SRH) information leading to various reproductive health (RH) problems including risky sexual debut, unwanted pregnancy, unsafe abortion as well as STI/HIV infections. Among known social variations which influence youth...

Unambiguous examples of ecological causation of sexual dimorphism are rare, and the best evidence involves sexual differences in trophic morphology. We show that moderate female-biased sexual dimorphism in bill curvature is the ancestral condition in hermit hummingbirds (Phaethornithinae), and that it is greatly amplified in species such as Glaucis hirsutus and Phaethornis guy, where bills of f...

Sexual dimorphisms, which are phenotypic differences between males and females, are driven by sexual selection. Interestingly, sexually selected traits show geographical variations within species despite strong directional selective pressures. This paradox has eluded many evolutionary biologists for some time, and several models have been proposed (e.g. 'indicator model' and 'trade-off model')....

The objective of this review was to describe sexual differentiation events in mammals, relating them to biosynthesis of sexual steroid hormones and their mechanisms of action. Cholesterol is the precursor of sexual steroid hormone biosynthesis via action of several enzymes converting these hormones. Progestagens hormones serve as substrate for the production of androgens, which in turn serve as...

This study was undertaken to gain a better understanding of dental hygiene students' attitudes toward AIDS and homosexuals. Each respondent received a 500-word patient case vignette and two scales for recording impressions of the person described in the vignette. There were four vignettes, identical except that the portrayed individual's illness was identified as either AIDS or leukemia, and se...

Female mating preferences can influence both intraspecific sexual selection and interspecific reproductive isolation, and have therefore been proposed to play a central role in speciation. Here, we investigate experimentally in the African cichlid fish Pundamilia nyererei if differences in male coloration between three para-allopatric populations (i.e. island populations with gene flow) of P. n...

The origin of species remains a central question, and recent research focuses on the role of ecological differences in promoting speciation. Ecological differences create opportunities for divergent selection (i.e. 'ecological' speciation), a Darwinian hypothesis that hardly requires justification. In contrast, 'mutation-order' speciation proposes that, instead of adapting to different environm...