Jill had lost her husband a few years ago to cancer, and during the months following his passing, deep loneliness had set in. After all, they had been together for over 30 years. Her best friend advised her to get a dog because they make great companions, so she did. A year later Jill and her best furry friend went everywhere together, a special bond had been formed. 

Pet parents talk about their furry friends like they're part of the family, and it often seems as though the family pooch is seen as another one of the kids.

In fact, when you speak to folks about what it's like to live with a dog, many will tell you that they discovered a degree of solace that's extremely difficult to achieve in relationships with people. That it's a way of experiencing solitude without the loneliness. 

And now behavioral science is starting to reveal how this friendship/bond came to be. 

Less than 20 years ago, scientific teams led by psychologist Michael Tomasello of the Max Planck Institute for Evolutionary Anthropology in Germany and Vilmos Csanyi in Budapest, independently published research papers on how family dogs can follow human pointing gestures to find hidden food. Maybe that doesn't sound like much, but that work marked the birth of a thriving field of investigation into the biological foundations of the human-dog bond. 

Since then researchers have learned that most people and their furry friends live in an attachment relationship, just like mothers and infants. Not only do they enjoy one another's company, but humans help dogs navigate modern society, and dogs, in return, help humans when they lack a specific ability, such as sight. 

Dogs are unique in the animal kingdom because they have figured out how to join the community of an entirely different species, which is evidence of sophisticated social competence. In other words, dogs have a good set of social skills, including the abilities to form attachments, regulate aggression, learn and follow rules, provide assistance and participate in various group activities.

It's a win-win situation for both species - but maybe humans get the better end of the deal.

Dogs can learn by watching us, which helps them master the rules in fitting into human groups. Dogs are often admired for their emotional sensitivity. 

For years academic researchers refused to attribute emotions to animals. That attitude is changing slowly. 

Another reason for the strong bond between dogs and humans is a chemical connection that happens in a loving gaze. 

Takefumi Kikusui, a professor of veterinary medicine at the Companion Animal Research Lab at Azabu University in Japan, wondered exactly what dogs are getting out of their affectionate gazing at humans. In the a new study in the journal Science, Kikusui and his colleagues measured the oxytocin levels of dogs and their pet parents before and after the pairs spent 30 minutes together. And after they spent quality time petting, playing, and gazing into their furry friend's eyes, both the people and dogs showed increases in the levels of oxytocin.

Oxytocin, often called the "love hormone," performs various actions in humans, such as reducing stress, and it also triggers the onset of labor. But in mammals, one of its key roles is to help a parent and infant bond. In humans, both moms and babies get a spike in oxytocin during breast feeding, and they will spend hours gazing at each other, which is nature's way of forming a bond.

The findings may help explain one of the most puzzling stories in human history: how a predatory, fearsome wolf transformed into man's best friend. Kikusui speculated that, at some point early in the domestication of dogs, a small group of naturally more friendly dogs may have gazed at humans for bonding.

More than one third of all Americans live with dogs today. Americans are in the midst of a genuine love affair with dogs: people are spending more money on their furry friends than ever before, and they are indulging their companions with more services than ever before, such as doggie daycare, doggie summer camp, doggie clothes and high-end doghouses. 

So this dance is about love. It's about attachment that's mutual and it's about a kind of connection that's virtually unknowable in human relationships because it's essentially wordless.