Exploring why males are larger than females among mammals

In most animals, females are larger than males, but in most mammals, males are larger than females. A new analysis published in Mammal Review examines the potential drivers of these differences.

In most animals, females are larger than males, but in most mammals, males are larger than females. A new analysis published in Mammal Review examines the potential drivers of these differences, calling into question the theory that only sexual selection is at play in mammals—that males compete to mate with females, and bigger males are more likely to win.

The analysis suggests that, alongside sexual selection, natural selection may be an evolutionary driver of sexual size differences in mammals. Males and females may have evolved to differ in size so that they could exploit resources such as food.