Most often, male mammals are not larger than females. Less than half of mammal species have this characteristic.
In almost 39% of cases, both sexes have the same mass and in 16% it is even the females who are heavier. We have long known that sexual dimorphism, the difference in size between males and females, is not entirely new, says Jean-Michel Gaillard, ecologist at the biometrics and evolutionary biology laboratory in Lyon. The study was published in the journal Nature Communications.