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Monkey 'queen' led a violent coup to become her troop's first female leader. Now her reign is in jeopardy.

A Japanese macaque bathing in a hot spring in winter. (Image credit: Mark Fox/Getty Images)

In southern Japan, a young female macaque has upended societal norms by seizing control of her 677-member troop through a violent primate coup. Now, her hard-won empire could come crumbling down around her due to one unstoppable force: mating season.

Meet Yakei, a 9-year-old female living in a Japanese macaque reserve called the Takasakiyama Natural Zoological Garden, where she has spent the last year reigning as the first female troop leader in the park's 70-year history.

A New York Times article published Jan. 21 chronicles the monkey matriarch's incredible rise to power: After assaulting her own mother and assuming the role of top female in the troop, Yakei embarked on a violent vendetta against her troop's four highest-ranking males, finally assuming the troop's coveted alpha position after beating up Nanchu — an elderly, 31-year-old male who had ruled the troop for five years.

Hostile takeovers by aggressive females are exceptionally rare in Japanese macaque society, with only a handful of recorded cases preceding Yakei's coup, Yu Kaigaishi, a research fellow at the Japan Society for the Promotion of Science, told The New York Times.

Japanese macaques (Macaca fuscata) — also known as snow monkeys for their habit of basking in hot springs when the weather gets snowy — live in strictly hierarchical societies, Kaigaishi explained; higher-ranking monkeys get greater access to food and mates. A male's rank is usually determined by how much time he has spent in a particular troop (males tend to leave the troop they were born into after reaching puberty), while female macaques inherit the rank just below their mother's. Sometimes, macaques can violently seize higher ranks.

These contests for position are almost exclusively between males, Kaigaishi said, which is why Yakei's rise to power was at once shocking and exciting to researchers who followed her case. After toppling the top male, Yakei even started to exhibit traditionally male behaviors, such as walking with her tail up and shaking tree branches with her body, experts at the reserve said.

However, after nearly a year in the top spot, Yakei's position may be in jeopardy during the chaos that is mating season — which typically runs from November to March. According to reserve researchers, an 18-year-old male named Luffy has been making unwanted courtship advances on Yakei since this year's breeding season began. Queen Yakei, meanwhile, seems to regard Luffy with fear.

"I observed that Yakei showed a facial expression (known as 'fear grimace') typical of subordinate individuals against Luffy," Kaigaishi told the Times in an email. "Also, I observed Luffy pushing Yakei away to monopolize food."

It's possible that Luffy is in the process of dethroning Yakei to rise as the troop's new alpha, the researchers said. Or, this could just be a simple matter of courtship, with Yakei showing Luffy that she isn't buying into his monkeyshines.

For now, Yakei holds onto her proverbial crown. Stay tuned to find out if her tale is about to get even more bananas. 

Originally published on Live Science.

Brandon Specktor
Brandon Specktor

Brandon has been a senior writer at Live Science since 2017, and was formerly a staff writer and editor at Reader's Digest magazine. His writing has appeared in The Washington Post, CBS.com, the Richard Dawkins Foundation website and other outlets. He holds a bachelor's degree in creative writing from the University of Arizona, with minors in journalism and media arts. He enjoys writing most about space, geoscience and the mysteries of the universe.