This is Arlo. I inherited him when my husband and I started dating in 2012. He is a soft and sensitive rescue with a penchant for laps and kisses on demand. I grew up with large breeds so Arlo wasn't totally what I had in mind for my first dog as an adult. Within eight weeks or so, he was one of my favourite things about planet earth. I love that animal.
Does he love me?
In How Dogs Love Us: A Neuroscientist and his Adopted Dog Decode the Human Brain, Dr. Gregory Berns writes,
Arlo expresses concern for my wellbeing regularly. If my husband and I are in different rooms, he will position himself exactly half-way between us to be able to keep an eye on us both. And then he promptly starts to snooze.
So what is this feeling that I get when I am around my dog? I know I am not alone here.
I've spent enough time in Asia and Central Asia to realize that the Western orientation to domesticated dogs is somewhat unique around the world. They think we're rich idiots on this one.
The research is just cresting really. Berns' research from 2012 proved that dogs could sit awake and unrestrained in a functional MRI so that we could map reward pathways.
Two rescues were trained to sit still for period of at least 5 seconds in the scanner. Their owners stood in their eye line giving hand signals. By mapping the reward association (TREATS!) onto hand signals, the researchers could assume what the dog was thinking while the image was being taken. That is, the 'treat' hand signal activated the reward pathways (in this case, the ventral striatum but that's not important) in the brain. And then they took a picture! And then they did the same for the 'no treat' hand signal and found less activation of the brain.
Ok, so dogs process social cues in their brains. They have thoughts. Big surprise. But how do we get from there to love?
In 1997, John Archer took an evolutionary approach to the love between dogs and their owners. He proposed that the evolutionary advantage of human-pet bonding lies in the seemingly unconditional love afforded by dogs to their owners. Dogs convince humans to love them by having baby-like characteristics as puppies and by personifying their owners. Archer believes that, for some, relationships with dogs are more rewarding than those with humans. Emily Bronte, author of Wuthering Heights, wrote about dogs quite a bit in her work. She had a Mastiff and described him as "both a bridge and a barrier" to human relationships (Adams 2000). Constable et al interviewed 127 Indigenous Australian dog owners about the significance of dogs in their community. Almost unanimously, the participants described dogs as guards and also enmeshed in their system of kin. Even when they're expensive, prone to illness or misbehaving, there appears to be a strong social advantage to having dogs. For me, this research proves a Darwinian logic to dog ownership but it doesn't yet prove love.
The newest round of thinking lands on oxytocin. Oxytocin, in humans, is an important hormone for lactation and uterine contractions during and after labour. Oxytocin is released from a gland in the brain and travels throughout the body to different receptors. However, oxytocin also hangs around the human brain. Oxytocin probably promotes maternal and sexual behaviour through this pathway but the research is very limited here.
When researchers ask, "Does my dog love me?" in the context of oxytocin studies, they are asking if oxytocin levels in the brain reflect real love in the animal or owner. This is a real leap for me, but here is what some very small studies have shown:
- In the first study of its kind, Romero et al (2014) showed that oxytocin sprayed into the noses of dogs, when compared to a control group who had saline sprayed into their noses, "enhanced social motivation to approach and affiliate with close social partners" including both owners and other dogs. They tested 16 dog-owner pairs. They found that baseline oxytocin was stable over time so it likely didn't have much to do with some dogs just being more social than others at baseline. The researchers propose that oxytocin has a key role in creating enduring social relationships over time.
- Women have statistically significant positive oxytocin reactivity to time spent playing with their dog versus sitting and reading after work. This was a 2015 study of ten women and their dogs. The study also ran with ten men and their dogs, but the men had negative oxytocin reactivity to playing with their dogs after work and reading after work. These findings point to many other variables (Miller et al 2015)
- There is a statistically significant positive relationship between how often female owners kiss their dogs and oxytocin levels in the owners and the dogs. Again, a very small, but well done, study (Handlin et al 2015). The same authors also tracked cortisol, oxytocin and heart rate over one hour of contact between ten women and their Labrador dogs and compared them to controls in a different study. Findings in the women with the Labs included an oxytocin surge at three to five minutes, reduced cortisol after 15-30 minutes and reduced heart rate after one hour. The oxytocin and the heart rate findings were also found in the dogs but, strangely, cortisol levels went up in the dogs.
- A long gaze between dogs and their owners resulted in increased oxytocin excretion in the urine of owners. The authors propose that the oxytocin mediates attachment between dogs and owners (Nagasawa et al 2015). However, a follow up study published by the same authors in Science showed that spraying oxytocin into the nose of dogs made them gaze longer at their owners. This kind of two way correlation is really helpful.
- Rehn et al (2014) showed that dogs who were physically and verbally engaged by their owners had lower cortisol levels and sustained release of oxytocin after one hour when compared to dogs that received only verbal contact or who were ignored.
In an Atlantic article on this very topic, the author refers to Charles Darwin's Expression of the Emotions in Man and Animals in which Darwin argued that different species felt the same emotions as other species. Given that he is the same guy that argued a relatively utilitarian view of the universe - natural selection through survival of the fittest - he must have believed there was some great advantage to our emotional lives.
The evidence is important and it does point to a biochemical basis for a deep bonding that we, in the English-speaking universe, call love. I guess this turns my home, and millions of others, into an interspecies love triangle but that's fine with me.