UNLABELLED Background. Several authors have examined the risk for sexually transmitted infections (STI), but no study has yet analyzed it solely in relation with sexual behaviour in women. We analyzed the association of sexual behaviour with STI risk in female university students of healthcare sciences. Methods. We designed a cross-sectional study assessing over three months vaginal intercourse...

Same-sex sexual behaviour is ubiquitous in the animal kingdom, but its adaptive origins remain a prominent puzzle. Here, I suggest the possibility that same-sex sexual behaviour arises as a consequence of the competition between an evolutionary drive for a wide diversity in traits, which improves the adaptability of a population, and a drive for sexual dichotomization of traits, which promotes ...

OBJECTIVES The authors aimed to examine whether changes in health risk behaviour rates alter the relationships between behaviours during adolescence, by comparing clustering of risk behaviours at different time points. DESIGN Comparison of two cohort studies, the Twenty-07 Study ('earlier cohort', surveyed in 1987 and 1990) and the 11-16/16+ Study ('later cohort', surveyed 1999 and 2003). S...