Do you ever look into your dog’s eyes… and wonder if they love you as much as you love them?
Science has some clues about that.
Animals can imprint on humans
In the early 1930s, an Austrian scientist named Konrad Lorenz kept a collection of goose eggs and waited until they hatched. When they emerged, the newly hatched goslings followed the first moving object they saw—in this case, Lorenz himself. After that fateful day, he could often be seen with a row of geese in tow, following him around the grounds.
Lorenz continued to study this type of animal behavior, which became known as imprinting. Imprinting refers to a critical period of time early in life when an animal forms parental attachment, often to their mother. Imprinting tells animals about who they are. Scientists found that there’s often a window of time in which imprinting has to happen in order to stick. In some species, this window may be as short as 30 minutes.
Imprinting in the animal kingdom is so powerful that if a lamb’s mother dies after giving birth, and the lamb is introduced to another mother within 30 minutes, that lamb will bond with the new mother (and vice versa) for the rest of their lives.
This research about how animals can imprint on humans (or on other animals or objects) made scientists think about how imprinting might be different from other kinds of learning. It seemed like imprinting was an innate behavior likely coded in an animal’s genes.
The “love” hormone
Emotionally, we already feel like our dogs are family. Science backs that up.
Some time after Lorenz’s studies, scientists discovered that the feel-good hormone oxytocin is involved in imprinting. Oxytocin is sometimes called “the love hormone” or “the social hormone,” because it is released when humans bond socially or romantically and triggers feelings of happiness.
Oxytocin is an important part of mother-child bonding in both humans and other mammals. This hormone helps a mother bond to her infant while nursing. Recent studies have shown that if a new mom and an infant look at each other, both people experience a spike in oxytocin levels. That leads to more bonding, creating an infinite loop.
According to our brains, we bond with our dogs in the same way. When you look at your dog, your brain produces more oxytocin. It works both ways—recent studies have shown that just looking at each other causes your dog’s oxytocin levels to go up, too. This kind of mutual oxytocin-based love was likely an important part of dog domestication. We don’t experience the same thing when gazing at wolves.
On a biological level, our brains use the same neurological pathway to process our love for our pets and our love for our children. It’s the same love hormone. Studies have shown that the same parts of the brain light up when people look at photos of their children and photos of their dogs.
Science tells us that the human–dog bond is mutual: we both experience happiness, and we both benefit.
The “happiness” hormone
Serotonin became famous in the 1970s because higher levels of serotonin in the brain lead to an elevated mood and less anxiety. Scientists have found that, just like oxytocin, dogs have higher levels of serotonin compared to wolves. This kind of happiness has to do with their relationship to humans—as dogs were domesticated, the human–dog bond became stronger, bringing both parties more happiness.
Dogs give us so much. Bonding with dogs benefits humans in many ways, more than just serotonin-induced happiness. Interacting with a dog can lower blood pressure, reduce stress, and provide other health benefits. That might be part of the reason why people who own pets tend to live longer.
Why we love puppy dog eyes
Neoteny is the name scientists give to what many of us think of as “cuteness.” It means that humans favor characteristics that make animals look young even when they’re adults—like larger heads and wide, innocent eyes—because it endears them to us. It can be seen in many domesticated animals, including cows, horses, and of course dogs.
In fact, the ability to make puppy dog eyes is one of the important characteristics dogs gained during evolution from wolves. Over thousands of years of domestication, dogs developed the movable eyebrows that allow them to make those puppy eyes that we find so cute. (Wolves don’t have the same facial muscles around their eyes that dogs do.) Our ancestors favored dogs with big, expressive eyebrows that made their eyes look bigger. Those big puppy eyes probably triggered a caregiving response in those early humans, which is still true today.
Dogs also evolved to make eye contact with humans when they seek guidance, which wolves don’t do. Scientists have called this type of eye contact “a hallmark of the relationship between dogs and humans.”
Looking at puppy dog eyes and looking at a newborn baby can cause the same emotional response to nurture in us. Which is why a dog feels just as much a part of the family as anyone else.
The psychology of dog love
Since Lorenz and his geese, scientists have found that imprinting is a component of the interaction between humans and companion animals. It can even play a role in determining who we love and who we live with.
Remember the scene from the movie 101 Dalmatians where Pongo sees people walking by with their canine mini-me? Although it seems unlikely, this phenomenon has been observed in the real world, too.
Some studies have suggested that this is not merely coincidence—on some level, we choose dogs that share traits with us. Just like preferring puppy dog eyes, humans select for traits that feel familiar. One study in Japan suggested that the key is again in the eyes—we might be subconsciously choosing dogs whose eyes are similar to ours.
No matter what science discovers in the future, it’s clear that our bond with our dogs runs deep. After many years of evolving and living together, our furry friends have become a beloved part of the family.