Are there any species of mammal where there are no significant behavioural differences between the males and females?

 Tengo en la nevera un artículo sobre la habilidad de las ratas desnudas para "vivir sin aire", algo que se ha publicado estos días y me ha entusiasmado, y su inmunidad al cáncer. Son animales interesantes de muchas maneras y bajo muchas ópticas, pero no únicos en cuanto a su organización social  en mamíferos. 

Gracias al protagonismo que le da la prensa estos días he podido recordar esta pregunta de Quora, y la respuesta, que pienso que revela aspectos poco conocidos del comportamiento de los mamíferos sociales, así que la traigo aquí. Como siempre digo, los textos pertenecen a los autores y no a los sitios donde se publican, y a pesar de que en mi blog tendrá menos difusión, están  donde deben estar-
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I'm going to give an easy example: naked mole rats, Heterocephalus glaber.
No. Reading the Wiki article I have discovered that in fact there are two eusocial species of animals, the other one es Damaraland rat,  Fukomys damarensis.

Naked mole rats: Image via reddit.

Damaraland mole rats, via Arkive, photograph of Wendy Dennis.

As you probably know, nake mole rats and Damaraland rats exhibit a behaviour that is considered eusocial.
This means they live in a colony in which only a female, and a few males (2 or 3 in mole rats, and 1 en Damaraland rats) produce offspring.

The naked mole-rat is the first mammal discovered to exhibit eusociality. This eusocial structure is similar to that found in ants, termites, and some bees and wasps.[35][36] Only one female (the queen) and one to three males reproduce, while the  rest of the members of the colony function as workers. The queen and  breeding males are able to breed at one year of age. Workers are  sterile,[36] with the smaller focusing on gathering food and maintaining the nest,  while larger workers are more reactive in case of attack. The  non-reproducing females appear to be reproductively suppressed, meaning  the ovaries do not fully mature, and do not have the same levels of  certain hormones as the reproducing females. On the other hand, there is  little difference of hormone concentration between reproducing and  non-reproducing males. In experiments where the reproductive female was  removed or died, one of the non-reproducing females would take over and  become sexually active. Non-reproducing members of the colony are  involved in cooperative care of the pups produced by the reproducing  female. This occurs through the workers keeping the pups from straying,  foraging for food, grooming, contributing to extension of tunnels, and  keeping them warm.[32]
The Damaraland mole-rat (Cryptomys damarensis) is the only other eusocial mammal currently known.