The haplodiploid sex-determination system of ants gives rise to conflict between queens and workers over colony sex ratios, and the female-biased allocation ratios seen in many species suggest that workers often prevail in this conflict. We exchanged queens between male- and female-specialist colonies of the fire ant Solenopsis invicta. These exchanges quickly reversed the sex-ratio biases of a...

It has been suggested that achievement in sports is correlated with a putative measure of prenatal testosterone the 2nd to 4th digit ratio (2D:4D). It has been shown that digit ratio (2D:4D) is negatively associated with prenatal testosterone, and it is also negatively associated with ability in sports. This study examined associations between 2D:4D and performance of both male and female Natio...

OBJECTIVES We evaluated female-condom use among women participating in an HIV/STD intervention designed to reduce unprotected sex and expand prevention strategies. METHODS Women (n = 360) were recruited from a family-planning clinic and were randomized into an 8- or 4-session intervention group or a control group. We conducted follow-up interviews at 1, 6, and 12 months. RESULTS At 1 month,...

BACKGROUND One-third of the world's men are circumcised, but little is known about possible sexual consequences of male circumcision. In Denmark (~5% circumcised), we examined associations of male circumcision with a range of sexual measures in both sexes. METHODS Participants in a national health survey (n = 5552) provided information about their own (men) or their spouse's (women) circumcis...

Whether the 370-371insACA, 494T>C, and 1423C>T haplotype in ubiquitin-specific protease 26 (USP26) gene is associated with male infertility is controversial. To clarify this issue, we conducted a meta-analysis based on the most recent studies. Eligible studies were screened by using PubMed and Embase. Pooled odd ratio (OR) with 95% confidence interval (CI) was calculated with fixed effect model...

INTRODUCTION This retrospective study analysed head and neck malignancies seen over a 19-year period at the University College Hospital, Ibadan. METHODOLOGY One thousand, one hundred and ninety two patients with head and neck malignancies were analysed according to age, gender, topography and histology. RESULTS There was an annual hospital frequency of 62 cases per year. The overall mean ag...

BACKGROUND The elucidation of the relationship between the morphology of the peripheral nerves and the diseases would be valuable in developing new medical treatments on the assumption that characteristics of the peripheral nerves in females are different from those in males. METHODS We used 13 kinds of the peripheral nerve. The materials were obtained from 10 Japanese female and male cadaver...

A key decision in the life of an organism is whether to be male or female. In Drosophila, each cell makes this choice independently of its neighbors such that diploid cells with one X chromosome (XY) are male and those with two chromosomes (XX) are female. In classic experiments carried out more than 80 years ago, Calvin Bridges made two important conclusions about how sex is determined in flie...