'Love Hormone' Turns Lions Into Placid Pussycats

THURSDAY, March 31, 2022 (HealthDay News) -- The "love hormone" oxytocin may be able to turn highly territorial lions into social sweethearts, researchers say.

Lions typically guard their turf fiercely, which can be a problem when they're on reserves or in captivity and have less space to share than they do in the wild.

The authors of a study published online March 30 in the journal iScience tested whether oxytocin could reduce potentially deadly territorial disputes between lions.

The researchers used hunks of raw meat to lure 23 lions at a wildlife reserve in South Africa to a fence so they could spray oxytocin up the lions' noses with a special device.

"By spraying the oxytocin directly up the nose, we know it can travel up the trigeminal nerve and the olfactory nerve straight up into the brain," said study first author Jessica Burkhart, a researcher at the University of Minnesota's Lion Center. "Otherwise the blood-brain barrier could filter it out."

After the spurt of oxytocin, the lions were more tolerant of other lions in their space and less vigilant when it came to unfamiliar lions, the investigators found.

"You can see their features soften immediately, they go from wrinkled and aggressive to this totally calm demeanor," Burkhart said. "They totally chill out. It's amazing."

The researchers assessed the lions' social tolerance by seeing how close they would allow others to approach when they had a favorite toy or when they had food.

"After the lions were treated with oxytocin, and we gave them their favorite pumpkin toy to play with, we saw the average distance between them drop from about 7 meters with no treatment to about 3.5 meters after oxytocin was administered," Burkhart said in a journal news release.

But oxytocin wasn't enough to increase lions' tolerance of others when there was food present. Watch the video below to see a researcher spraying oxytocin up a lion's nose while giving it raw meat:

The oxytocin-treated lions did show significantly less vigilance toward potential intruders, never roaring in response to recorded roars of unfamiliar lions. Untreated lions always roared in response, the researchers noted.

"Currently, we're working on introductions of animals who have been rescued from circuses or overseas or war zones that now live in sanctuaries," Burkhart said.

"The hope is that this will translate to animals being relocated in the wild, helping them to become more inclined to their new social environment so they're more curious and less fearful, leading to more successful bonding," she added.

More information

The American Psychological Association has more on oxytocin.

SOURCE: iScience, news release, March 30, 2022