Children differ in how quickly they reach linguistic milestones. Boys typically produce their first multi-word sentences later than girls do. We ask here whether there are sex differences in children's gestures that precede, and presage, these sex differences in speech. To explore this question, we observed 22 girls and 18 boys every 4 months as they progressed from one-word speech to multi-wor...

Sex differences in the experience of pain have been widely reported, with females generally reporting more frequent clinical pain and demonstrating greater pain sensitivity. However, the mechanisms underpinning such differences, while subject to intense speculation, are not well-characterized. Catastrophizing is a cognitive and affective process that relates strongly to enhanced reports of pain...

Lifespan and ageing are strongly affected by many environmental factors, but the effects of social environment on these life-history traits are not well understood. We examined effects of social interaction on age-specific mortality rate in the sexually dimorphic neriid fly Telostylinus angusticollis. We found that although interaction with other individuals reduced longevity of both sexes, the...

Letters Virus-host interactions and the unusual age and sex distribution of human cases of influenza A(H7N9) in China, April 2013 Over the past two weeks, Eurosurveillance has published several timely papers related to the emergence of a new influenza A(H7N9) virus affecting humans in China [1-3]. Genetic studies by Kageyama et al. [1] and Jongens et al. [2] assessed evidence in the genome for ...

Sex is determined in Drosophila by the activity of the Sex-lethal master regulator. Activity of Sex-lethal is initiated early in females by chromosome-counting transcription factors, then reinforced by signaling through the Janus kinase pathway.

The authors assess sex differences in the importance of 10 basic values as guiding principles. Findings from 127 samples in 70 countries (N = 77,528) reveal that men attribute consistently more importance than women do to power, stimulation, hedonism, achievement, and self-direction values; the reverse is true for benevolence and universalism values and less consistently for security values. Th...

Modification of offspring sex ratios in response to parental quality is predicted when the long-term fitness returns of sons and daughters differ. One factor that may influence a mother's sex allocation decision is the quality (or attractiveness) of her mate. We investigated whether the sex ratios of offspring produced by female Drosophila melanogaster are biased with respect to the age of the ...

Men are overrepresented in socially problematic behaviors, such as aggression and criminal behavior, which have been linked to impulsivity. Our review of impulsivity is organized around the tripartite theoretical distinction between reward hypersensitivity, punishment hyposensitivity, and inadequate effortful control. Drawing on evolutionary, criminological, developmental, and personality theor...

In human populations, variation in mate availability has been linked to various biological and social outcomes, but the possible effect of mate availability on health or survival has not been studied. Unbalanced sex ratios are a concern in many parts of the world, and their implications for the health and survival of the constituent individuals warrant careful investigation. We indexed mate ava...

Unrelated same-sex individuals pairing together and cooperating to raise offspring over many years is a rare occurrence in the animal kingdom. Cooperative breeding, in which animals help raise offspring that are not their own, is often attributed to kin selection when individuals are related, or altruism when individuals are unrelated. Here we document long-term pairing of unrelated female Lays...