In most mammal species, males and females are the same size — or females are bigger

Hello Nature readers, would you like to get this Briefing in your inbox free every day? Sign up here. The most dimorphic species was the northern elephant seal (Mirounga angustirostris), where males had a mean mass 3.2 times that of females (Michele and Tom Grimm/Alamy) An analysis of more than 400 mammal species is overturning … Read more