"Love hormone" oxytocin shown to chill out fierce lions
Oxytocin is a hormone found in most animals. In humans it plays a fundamental role in childbirth, and has been informally referred to as the "love hormone" because it influences social bonding, particularly between a mother and child.
But what happens when you spray a big territorial carnivore in the face with oxytocin? Researchers working in a South African wildlife reserve have been experimenting with the effects of oxytocin on lions in an attempt order to answer that question, and their findings have been reported in a new study published in the journal iScience.
Lions are highly social animals. They can be deeply loyal and protective of members of their pride, but they can also be incredibly territorial and aggressive towards other groups of lions. This can be a major problem when trying to relocate the animals to areas already populated with other lions.
"Our prior research on wild lions in the Serengeti showed that the lions' complex social system derives from a strong sense of 'us vs. them’,” explained study co-author Craig Packer to Newsweek. “Their incredibly close social relationships are largely driven by the dangers posed by neighboring groups—the larger group wins and pride mates work together to repel strangers from their territories.”
So the goal of the new research was to explore whether oxytocin can be used to influence the animals social behaviors, and perhaps ultimately, better integrate lions into a pre-existing pride. To do this the researchers first needed to find a way to safely administer the oxytocin. According to first author on the study Jessica Burkhart, the trick was to fill up a tiny spray bottle with oxytocin and lure the animals with raw meat. When distracted, the lions had the oxytocin sprayed up their nose so the hormone could quickly take effect in the animals’ brain.
“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 Burkhart. “Otherwise the blood-brain barrier could filter it out.”
One test the researchers used to measure the effect of oxytocin was introducing a play object and tracking how close a lion playing with that object allowed other lions. Generally the animals keep well away from others when playing with objects but under the influence of oxytocin the lions significantly reduced proximity to others.
“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,” explained Burkhart.
Another experimented tested the animals’ roar responses when under the influence of oxytocin. Roar response tests are generally considered a good indication of territorial vigilance, letting potential intruders know they should back off.
Compared to control tests, the researchers found oxytocin significantly reduced the animals’ roar responses. Anecdotally, Burkhart said this the oxytocin-treated lions quickly turned into calm, chilled out animals.
“You can see their features soften immediately, they go from wrinkled and aggressive to this totally calm demeanor,” added Burkhart. “They totally chill out. It’s amazing.”
Interestingly, the researchers found oxytocin had little effect on possessive behaviors during a food response experiment. When a small food object was introduced to the group the animals displayed competitive aggressive behaviors regardless of the oxytocin. This suggests there are certain limits to the prosocial behaviors generated by the hormone.
Beyond simply being an interesting academic “what would happen if” experiment, the researchers do note there are real-world implications to these findings. In Africa lions frequently need relocation when urban sprawls encroach on their territory. But relocating the animals can cause territorial conflicts with other prides.
Further research will be needed to explore oxytocin in lions, but the hope is the hormone could be used to help form social bonds when new animals are introduced in areas with pre-existing prides. Burkhart also said her team is investigating the effect of oxytocin on lions rescued from captivity as they are reintroduced into larger social groupings.
“Currently we’re working on introductions of animals who have been rescued from circuses or overseas or war zones that now live in sanctuaries,” said Burkhart. “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.”
The new study was published in the journal iScience.
Source: Cell Press