Meerkat queens have high testosterone, and their pups pay a price

When we think of testosterone-driven dominance, images of silverback gorillas pounding their chests or executives battling for boardroom supremacy may come to mind.

Traditionally, the narrative of aggression and dominance has belonged to males. But in the dry savannahs of southern Africa, one species flips the script. Here, meerkats females are the competitive and dominant sex due to their testosterone.

Most meerkat mobs, small social groups of these mongoose relatives, are led by a dominant female. She commands with an iron paw – growling, biting, and shoving to maintain order.

This leadership style ensures that subordinates not only obey but also help raise her pups. Now, a recent study reveals that the dominant female’s reign comes at a price, particularly for her offspring.

Testosterone levels in meerkat queens

Meerkat queens owe their dominance to elevated levels of testosterone. During pregnancy, their testosterone can double, surpassing that of their male counterparts.

This hormonal surge strengthens the matriarch’s competitive edge, enabling her to maintain control. However, this advantage comes with a trade-off.

“While this chemical boost gives her a competitive edge and helps her keep the upper hand, it can also take a toll on the health of her offspring,” noted Duke University’s Christine Drea, co-author of the new study.

The research sheds light on the impact of elevated testosterone levels on meerkat pups. Conducted at the Kuruman River Reserve in South Africa’s Kalahari Desert, the study examined 195 meerkats across juvenile and adult stages.

High testosterone impacts meerkat health

The researchers analyzed the droppings of meerkat pups for signs of parasitic infections, including tapeworm eggs.

They discovered that pups born to dominant females, exposed to heightened testosterone levels in the womb, carried more gut parasites than those of subordinate females.

To confirm the role of maternal testosterone, the team administered a medication to some pregnant dominant females.

This treatment reduced the effects of testosterone during their third trimester. The results were striking: pups from these treated mothers exhibited stronger immune responses and fewer parasites.

Blood tests revealed that these pups had enhanced natural defenses against bacterial infections. Additionally, their chances of surviving past their first year significantly improved.

“The offspring from moms whose androgens were blocked actually survive significantly longer,” Drea noted.

Testosterone and immune health

This study provides the first evidence in mammals that elevated prenatal testosterone can weaken immune function.

The impact was most evident in juvenile meerkats, with the health disparities diminishing as the animals matured.

“There’s a health trade-off with testosterone,” Drea explained. “It’s actually having an effect on survivorship when the animals are the most vulnerable.”

Challenges faced by wild animals

The findings are part of a broader effort to understand how animals cope with infections in the wild.

Unlike the controlled environment of a laboratory, wild meerkats face a variety of challenges, including social status, hormones, and environmental stressors.

“By studying wild meerkats, we can explore how real-world conditions — factors like social status, hormones, and environmental stressors — interact to influence immune function,” said study co-author Kendra Smyth-Kabay, a former graduate student.

Meerkat dominance beyond testosterone

Meerkat queens do not rise to power through sheer chance. These matriarchs typically inherit their position after the previous leader dies or is ousted.

Once in charge, they exert strict control over breeding within their groups. Subordinate females are often prevented from reproducing, either through physical aggression or by hormonal suppression caused by the dominant female’s presence.

This social structure ensures that the queen’s pups receive the majority of the group’s care and resources. Meerkat queens also have an uncanny ability to recognize and expel potential threats to their reign, including older offspring that may challenge their authority.

Interestingly, their leadership style often involves collaboration as much as it does competition. They rely on the support of loyal subordinates to maintain their dominance and rear their young.

The lifespan of a meerkat queen can vary, but those who maintain their dominance often live longer than subordinates, benefiting from better access to food and protection from predators.

However, the constant stress of defending their position can take a toll, making their reign both a privilege and a burden.

A balance of power

The study highlights the trade-offs in meerkat society. Dominant females gain reproductive success and control, but their pups bear the burden of weakened immunity. These findings provide a glimpse into the complex interplay of hormones, social hierarchy, and health in the animal kingdom.

As researchers continue to examine these dynamics, the fierce matriarchy of meerkats offers valuable insights into the cost of dominance – particularly the role of testosterone in shaping their leadership and its impact on offspring health.

Despite their apparent power, even queens face the consequences of their reign.

The study is published in the journal Ecology and Evolution.

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