Lions got super sweet after sniffing oxytocin

A male and female lion lie down together at Berlin Zoo.

Lions in an enclosure at Berlin Zoo.
Photo: TOBIAS SCHWARZ/AFP (Getty Images)

Scientists in South Africa recently lured captive lions to a fence with raw meat, then snorted the hormone oxytocin into their noses. The unusual experiment aimed to find out if the so-called love hormone could make big cats friendlier to each other – and that’s exactly what happened.

Oxytocin is a warm, fuzzy natural drug; in humans, it can reduce blood pressure and cortisol levels, increase pain thresholds, and stimulate social interaction. Recent evidence that it has a similar effect on lions could be a boon to conservationists in Africa, who increasingly need to introduce strange lions to one another as natural territory expands. shrinks. The study is published today in iScience.

Although oxytocin has beneficial social effects on mankind, it behaves differently in other species. Some monkeys can act so as to release natural oxytocin when grieving, and invertebrates like starfish use an oxytocin-like hormone to turn their stomach, to regulate food intake. This test was the first investigation into the effect of oxytocin on a social group of carnivores, so there was no guarantee that the lions would relax when inhaling the hormone. But they did.

The researchers observed how the lions engaged in three types of behaviors when on and off oxytocin. In one case, the animals were given a pumpkin to play with; in another, they were given a popsicle of frozen blood; and in a third scenario, the researchers played a recording of a roar for the lions, mimicking a territorial challenge from an unfamiliar cat.

“The most impressive measure was the decrease in territorial roar,” study author Jessica Burkhart said in an email to Gizmodo. “It is common for lions to roar in response to unfamiliar roars and in this case, after being given oxytocin, the roars actually stopped altogether.”

When in possession of the pumpkin, lions on oxytocin also allowed other lions to approach much closer, a sign that the hormone increased the cats’ social tolerance. Burkhart, a neurobehaviouralist at the University of Minnesota Lion Center, said in a Release that the effects of oxytocin were evident even on the lions’ faces. “You can see their features soften immediately, they go from wrinkled and aggressive to this totally calm demeanor,” she said.

A lioness and her cub in a Moroccan zoo in February.

A Barbary Lions and her cub at the Rabat zoo in Morocco
Photo: FADEL SENNA/AFP (Getty Images)

The lions refused to share their blood popsicles, oxytocin or not. Burkhart noted that it was likely an instinct that kicked in because the object involved was food, not just a toy. But the cats received a very low dose of the drug (10 IU) even compared to certain doses the dogs received (40 IU), despite being a fraction of the size of lions. Maybe with more oxytocin, cats would even be generous with their bloody treats.

Research indicates that oxytocin could be used to help manage lion populations in the future. As human habitation encroaches on lion territory, animals are sometimes transported to private reserves. This results in lions of different prides sharing lands and mingling. It can be a shocking experience for cats, but maybe a dose of love hormone would make the transfer more peaceful for everyone.

“We will be able to administer oxytocin when the animals are anesthetized and moved to the new location,” Burkhart said. “Ideally, this will decrease the animals’ fear and increase their curiosity and desire to bond, giving them a better first impression of their new social environment.”

The practice is already being tested with the collaboration of carnivore veterinarians and conservation groups. Team members are now also testing the effect of oxytocin on other carnivores such as tigers, leopards and hyenas.

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