In many bird and mammal species, males are significantly larger than females. The prevailing explanation for larger-sized males is that sexual selection drives increased male size. In addition, researchers commonly assume that the extent of dimorphism indicates the strength of selection for increased size in males. Here, through reconstruction of ancestral morphology for males and females of on...

Manipulation of Drosophila melanogaster genomes allows large numbers of genes to be transmitted solely through males, thereby allowing selection to optimize flies for male function alone. It seems biasing phenotypes toward the male optima has serious fitness costs for females.

Everybody who works in the field of injuries knows that after infancy, and before old age, males engage in more behavior that exposes them to the risk of injury, experience more injuries, and die more frequently from injuries. For example, in the US, among 15 to 19 year olds, males are 2.5 times as likely as females to die of any unintentional injury, and about five times as likely to die of ho...