Humans and Dogs: A History

People have a special connection with dogs. More households have a dog than any other kind of pet, and they have had a significant place in culture going back thousands of years. Even the cat-crazy ancient Egyptians kept pet dogs. However, where does this connection originate from?

My own dog

To fully answer this question we have to understand where dogs came from. Genetic analysis shows that dogs likely diverged from wolves at least 27,000 years ago. It seems likely that modern dogs originate from wolves that cooperated with humans. In the time since, they have undergone several changes that likely lead to the special connection we have with them.

Though they may be cuter, in my experience, chihuahuas are just as vicious(Images from here and here, respectively).

In the time since they have diverged from wolves, us humans have bred them into breeds with certain characteristics. While they are not separate species and are capable of interbreeding, the breeds we have created are very distinct with their own traits that separate them from each other. However, in our creation of these breeds, the selective breeding they have undergone has led to the introduction of some negative traits. The inbreeding that purebred dogs go through has led to a higher rate of genetic disease, particularly cancer relative to crossbred dogs. In addition, some of the traits we have bred into them are harmful. Most notably, the bulldog was bred for its distinctive short face, but this has actually led to an increased mortality rate.

Perhaps the most obvious reason for our relationship with dogs is their ability to understand us. Research has shown that dogs do have the ability to understand some human visual communication. However, even without that research, any dog owner could tell you that their dog absolutely can pick up on their body language. Speaking purely from my own personal experience, I know that my dog not only can pick up on my mood, but reacts to it, showing sympathy and excitement when appropriate. In addition, people read, correctly or not, certain emotions in dog communication.

In addition to this, people and dogs are sort of hardwired to like each other. When a person interacts with a dog, levels of certain hormones are elevated or lowered. In particular, touching a dog results in elevated levels of oxytocin and lowered levels of cortisol. Oxytocin is a hormone that affects, among other things, social bonding, and particularly is associated with maternal feelings following childbirth, and cortisol is a hormone associated with the stress response. What's more, it has been shown that the release of oxytocin can cause a positive feedback loop leading to additional oxytocin release in both human and dog. This is consistent with what people actually experience with their dogs. People definitely do have an affection for dogs that is similar to that they might have with children, and interacting with my dog does help to destress after a tough day. 

The relationship between dogs and humans is totally unique. Unlike most other domesticated animals, with the possible exception of cats, people don't typically expect any benefit from having a dog, while other domesticated animals, like cows or horses are typically raised for their capabilities or products. This sort of totally non-beneficial relationship is an interesting result of tens of thousands of years of evolution that have led to the bizarre, wonderful relationship the human race has with our beloved canine companions.