You are used to see the fierce competition between males for achieving sex: the testosterone overload triggers a high dose of aggressiveness, transliterated to violence till, sometimes, death: from deer to tigers, from bison to bears.

Males grow antlers, bright plumage, sing songs and so on ...

But what if the roles change? And this indeed happens in many shore birds ...But in mammals, too ...

Usually, females in most species pay the greatest toll in raising offspring, while males often just copulate and move on. That's why females seek the best males in order to get the best genes, while males just fight for as many mates as possible, just to spread their semen.

Females do not need to compete in this case, as valuable males would be willing to procreate with all the pretenders. But this is not the case of meerkats, mongooses that live in colonies of 3 to 50 animals, in which a single dominant couple reproduce, while the rest of the group cares for their pups.

A 12 years study made in the Kalahari Desert (southern Africa) explained how females keep the "queen" status. 33 dominant females and 53 dominant males were monitored. Dominant females transmitted their genes to nearly twice as many individuals than the dominant males. This is quite a difference compared to the general animal case! This happened because alpha females kept on average their position for 32 months, nearly twice as long as the dominant males. (the longer they remained dominant, the more pups they could raise to adulthood).

In this case, fighting for dominance is really worth for females! "When given the chance to attain dominance, females should be going all out to make sure they get it," said team member Sarah Hodge of the University of Cambridge.

Subordinate adult females were extremely aggressive (till physical violence) to other females that were trying to breed twice as often as subordinate males fought their competitors.

Dominant female meerkats possessed all the tools to use and keep their dominance: they were more than 10% heavier than the subordinates (enabling them to carry more offspring) and had three times as much testosterone, providing them the aggressiveness needed to maintain dominance.

"The data" returns to the original concept [of sexual selection] outlined by Darwin himself --that is, competition for opportunities to breed, not just opportunities to mate," says animal behavior expert Mark Hauber of the University of Auckland, New Zealand.