Most people who have pets know how easy it is to become attached to them. But can dogs and cats love their people in return?
That was the question Paul Zak, a professor of economics at Claremont Graduate University and the author of The Moral Molecule: The Source of Love and Prosperity, had after his own interactions with pets. He decided to look into the matter and investigate the bonds between people and pets.
His question was if pets cause people to release oxytocin, the neurochemical of love. It’s traditionally associated with nurturing one’s own offspring and is sometimes called the “trust hormone.”
Zak calls oxytocin the “moral molecule” because it helps people treat others with “care and compassion.” In studies, pleasant human interaction has caused the release of oxytocin, which makes people care about others, strangers included, even if temporarily. This can range between such situations as dancing or meditating in a group.
The experiment started with 100 participants in a lab. Blood samples established their baseline physiologic states. Then the participants were played with a dog or cat for 15 minutes in a private room. After playtime, a second blood sample was taken; participants then interacted with each other to see how they behaved with other humans.
The study revealed that oxytocin increased 30% after playing with a cat or dog. They also figured something else out: with dogs, results could depend on the lifetime number of pets someone had owned.
It was the opposite for those interacting with cats. “Greater lifetime pet ownership caused oxytocin to fall linearly,” Zak reported. That means people who had cats the longest released less bonding hormone while interacting with cats. “Dogs are simply more ‘people-oriented’ than cats, and previous pet ownership seems to have trained our brains to bond with them.”
In contrast, previous studies showed that when humans interact with each other, oxytocin levels typically increase about 10% to 50%. The differences depend largely on the relationships between the people. For example, if someone shakes hands with a stranger, it might only be a 5% to 10% increase. If someone hugs his or her own child, however, it might go as high as 100%.
Also, the study found that dogs typically reduced stress hormones better than cats. When stress hormones were lowered, people in the experiment were trusting with, say, allowing strangers to hold their money.
Another part of the experiment revealed that some mammals, dogs included, participate in the human behavior of play. Could that, researchers wondered, mean animals could form friendships like humans do?
To test this theory, Zak traveled to an animal refuge in Arkansas. He obtained blood samples from a domestic mixed-breed terrier and a goat that play with each other regularly. “Their play involved chasing each other, jumping towards each other, and engaging in simulated fighting (baring teeth and snarling),” Zak said.
The dog and the goat, both young males, played together in an enclosure for 15 minutes. The dog’s oxytocin increased 48%, indicating he was attached to the goat and viewed him as a “friend.”
The goat experienced a 210% increase in oxytocin, indicating that the goat might have been in love with the dog. “The only time I have seen such a surge in oxytocin in humans is when someone sees their loved one, is romantically attracted to someone, or is shown an enormous kindness,” says Zak. “That animals of different species induce oxytocin release in each other suggests that they, like us, may be capable of love. It is quite possible that Fido and Boots and may feel the same way about you as you do about them. You can even call it love.”