Butterflies exhibit striking differences between males and females, a phenomenon called sexual dimorphism. These variations, ...

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Researchers who analyzed data from zoo animals found that it is not only genetics, but mating pressures that may determine ...

Among mammals, females generally live longer. The recent comparative study examined 528 mammal species in zoos and found that ...

A lower percentage of males improves mating behaviour and feather cover, with similar reproduction results and higher ...

Women usually live longer than men, and animals show the same pattern. Evolution, genes, and parenting explain why.

In mosquitofish, of the genus Gambusia, male fish are smaller than females -- sometimes only half the size. Biologists had previously assumed that smaller male mosquitofish had at least some ...