Honest olfactory ornamentation in a female-dominant primate.

Sexual selection theory predicts that potential mates or competitors signal their quality to conspecifics. Whereas evidence of honest visual or vocal signals in males abounds, evidence of honest signalling via scent or by females is scarce. We previously showed that scent marks in male lemurs seasonally encode information about individual heterozygosity - a reliable predictor of immunocompetence and survivorship. As female lemurs dominate males, compete over resources, and produce sexually differentiated scent marks that likely evolved via direct selection, here we tested whether females also advertise genetic quality via olfactory cues. During the breeding season specifically, individual heterozygosity correlated negatively with the diversity of fatty acids (FAs) expressed in labial secretions and positively with the diversity of heavy FA esters. As odour-gene relationships predictive of health and survivorship emerged during a period critical to mate choice and female competition, we posit that genital scent marks function as honest olfactory ornaments in females.

Guidelines on the assessment of bleeding risk prior to surgery or invasive procedures. British Committee for Standards in Haematology.

Unselected coagulation testing is widely practiced in the process of assessing bleeding risk prior to surgery. This may delay surgery inappropriately and cause unnecessary concern in patients who are found to have 'abnormal' tests. In addition it is associated with a significant cost. This systematic review was performed to determine whether patient bleeding history and unselected coagulation testing predict abnormal perioperative bleeding. A literature search of Medline between 1966 and 2005 was performed to identify appropriate studies. Studies that contained enough data to allow the calculation of the predictive value and likelihood ratios of tests for perioperative bleeding were included. Nine observational studies (three prospective) were identified. The positive predictive value (0.03-0.22) and likelihood ratio (0.94-5.1) for coagulation tests indicate that they are poor predictors of bleeding. Patients undergoing surgery should have a bleeding history taken. This should include detail of previous surgery and trauma, a family history, and detail of anti-thrombotic medication. Patients with a negative bleeding history do not require routine coagulation screening prior to surgery.