A single whiff of oxytocin, a chemical that some call the “love hormone,” promotes tolerance among lions at a wildlife sanctuary.
Karen Hopkin: This is Scientific American’s 60-Second Science. I’m Karen Hopkin.
They say that lions are the king of the jungle. But a recent study shows that a single spritz of oxytocin…a hormone known to promote social bonding…renders even the most ornery alpha a total pussycat. The findings appear in the journal iScience.
Craig Packer: The greatest thing about watching lions is… lions are so openly and extravagantly affectionate with each other.
Hopkin: Craig Packer, director of the Lion Center at the University of Minnesota. He’s been traveling to the Serengeti since the 1970s to study the social behavior of these big cats.
Packer: They just rub each other with their foreheads, their chins are in each other’s faces. I mean they’re just really into each other. And then when they calm down and it’s time to go back to sleep…one will flop down and the other will flop on top of it. So it’s very endearing.
Jessica Burkhart: I’ve always loved lions.
Hopkin: Jessica Burkhart is a grad student in Packer’s pack.
Burkhart: But what is it about lions that is so different than their closest relative the leopard, and then their next closest the tiger, who are completely solitary?
Hopkin: And the first thing that came to mind was: oxytocin.
Packer: They call oxytocin the love hormone. But that sounds like Love Potion Number Nine. I prefer to think of it as the affection hormone. if you have a nice warm hug, that burst of feeling you get, that’s oxytocin. And so the lions would be like a perfect example of a species where you want to see what you can do with the oxytocin.
Hopkin: They conducted the study at a wildlife sanctuary in South Africa….where their first challenge was figuring out how to get the hormone into the lions.
Packer: Jessica… surprised me with this perfume sprayer, which I just thought was so ingenious and it worked out really really well.
Burkhart: It’s like a little glass bottle with a long tip and then there’s a bulb. So I have to pump the bulb and then the tip is about six inches long.
Hopkin: Burkhart would lure a lion over to the enclosure fence by waving a tasty hunk of meat.
Burkhart: Once I hold that meat and the animal’s grabbing it I can just stick it in the fence and into their nostril and spray away. [giggles]
Hopkin: The cats put up with the nasal invasion…as long as they got their grub. But if Burkhart spritzed a lion after the meat was gone….
Burkhart: You should see their faces. They go, huh? Like, how dare you take a cheap shot on me. They take it personally! [laughs…] Ah, it’s so funny.
Hopkin: The researchers then assessed oxytocin’s effects in several different behavioral situations. The first was seeing whether the hormone would make a lion less territorial when it comes to a desirable toy or a snack. Normally, lions are pretty protective of their possessions, particularly those that can be eaten.
Burkhart: They’ll growl and they’ll snarl and … they smack and they scratch and they snap. So a lot of times you will just get this sort of reactive behavior where they’re gonna lash out, to be like: Get off!
Hopkin: When it came to the toys, oxytocin did help to curb that reactive behavior, allowing other lions to come much closer. But it didn’t do much for their monopolistic attitude toward meals, which Burkhart says was not entirely unexpected.
Burkhart: With the toy, you know you’re playful, you might be more inclined to having your partners play with you. When you have a food object, it’s a much more primal instinct, so with the food trial, it’s that innate desire to survive that causes this very reactive aggression.
Hopkin: Seeing that oxytocin suppressed aggression in one situation, but not the other, actually reassured the researchers that the hormone wasn’t just making the lions totally dopey.
Burkhart: It doesn’t make your brain completely different, but it’s like drinking your coffee in the morning.
Hopkin: But if you’re a testosterone-fueled grumpy Gus, it could render you almost delightfully demure.
Burkhart: Oh my gosh, within minutes of the oxytocin that guy was completely chilled out. And I mean when we were giving him his oxytocin, he was growling, smacking the fence, totally insane, testosterone brain. And then he just completely mellowed out.
Hopkin: But even more dramatic was the third test…in which the researchers played an audio recording of an unfamiliar lion’s roar.
[Unfamiliar lion roar recording]
Hopkin: Which can be as unnerving as it sounds.
[Unfamiliar lion roar recording]
Packer: It’s like having a stranger in your bedroom saying I own this place, right?
Hopkin: Now, in the control conditions…in which lions got spritzed with a simple saline solution…about half of them roared in return, maybe 50 or 60 times.
Burkhart: That’s about right. So half of the lions are gonna actually roar and the other half are gonna be looking, probably standing behind the guy that’s roaring, and just looking and watching.
Hopkin: But when the lions were dosed with oxytocin…
Burkhart: There were zero. I mean, zero. They completely did not roar. That was astounding.
You could just see this difference in demeanor. They just laid there and they looked, they turned their heads, they were curious and they watched. But they’re not getting up, puffing up, scent marking, and roaring, roaring, roaring.
Packer: With the oxytocin it was like, huh, strangers. No big deal. And in some cases it seemed they were more interested in head rubbing with each other rather than worrying about the stranger.
Hopkin: The results give the team hope that oxytocin could provide a more effective way to introduce new lions into sanctuaries or reserves.
Packer: Because getting animals to become used to and accept strangers in their midst is an enormous challenge.
Hopkin: That would be a big boost for conservation efforts.
Burkhart: And … very key to using oxytocin to actually make a difference in the world.
Hopkin: A world with more tolerance and less roaring. It sounds darn near purr-fect.
Hopkin: For Scientific American’s 60-Second Science, I’m Karen Hopkin.
Burkhart: So lions will do these sequences where they’re like, roar, roar, uhh, uhh, uhh, and then they do grunts.
[A lion roaring and grunting]
[The above text is a transcript of this podcast.]