Scientists from Duke University have found that some female meerkats produce more testosterone than their male counterparts. High-ranking females are very aggressive and live longer than subordinate meerkats. The team’s findings were just published in the journal Scientific Reports.
Meerkats (Suricata suricatta) are tiny carnivores that belong to the mongoose family. They live in huge underground burrows and are known for their sentry behavior, which is done in shifts. Meerkat clans are led by the dominant female and she’s the only one allowed to mate. Also known as the “alpha female”, she will kill any pups that aren’t her own and may kick out the females who birthed them. Meerkat groups are highly cooperative and social.
A team of researchers studied wild meerkats living in the Kuruman River Reserve in South Africa. Individual animals were given unique identities and the team took blood samples to measure hormone levels. The team found that the highest ranking females were hormonally masculinized. Dominant females had equal or higher levels of testosterone compared to males, a phenomenon not seen elsewhere in the animal kingdom. They also had increased levels of other male hormones, including androstenedione, which is converted to testosterone in the body.
Even in other species with dominant females, males still have higher levels of masculine hormones. Meerkats are the exception and this might explain the aggressiveness of alpha females. Dominant females attack and steal food from lower ranking meerkats. They also have no tolerance for pups that aren’t their own, killing them to prevent competition. High levels of testosterone contribute to these behaviors, which have multiple benefits for the highest ranking females. Alpha females live longer, successfully raise more offspring, and get access to more food.
High levels of male hormones seem to contribute to the highly aggressive behaviors of dominant female meerkats. This is the first known case of an animal species with a reversal of sex hormone patterns.
Davies et al. Exceptional endocrine profiles characterise the meerkat: sex, status, and reproductive patterns. Scientific Reports (2016).