Clive Wynne's new book 'Dog is Love: Why and How Your Dog Loves You' says a dog's love is true

Dogs are the most loved animals on the face of the earth.

People who own dogs consider them equal to family. Treat them as important as one, sometimes even more.

The idea that animals can experience love was once anathema to the psychologists who studied them, seen as a case of putting sentimentality before scientific rigor.

But a new book argues that, when it comes to dogs, the word is necessary to understanding what has made the relationship between humans and our best friends one of the most significant interspecies partnerships in history.

A woman kisses her dog while posing behind a heart-shaped pastry during a flashmob in Paris.

Clive Wynne, founder the Canine Science Collaboratory at Arizona State University, makes the case in "Dog is Love: Why and How Your Dog Loves You."

The animal psychologist, 59, began studying dogs in the early 2000s, and, like his peers, believed that to ascribe complex emotions to them was to commit the sin of anthropomorphism -- until he was swayed by a body evidence that was growing too big to ignore.

Titles like "The Genius of Dogs" by Brian Hare have advanced the idea that dogs have an innate and exceptional intelligence.

Wynne, however plays spoilsport, arguing that Fido is just not that brilliant.

For Wynne, the next frontiers of dog science may come through genetics, which will help unravel the mysterious process by which domestication took place at least 14,000 years ago.

Indonesian dog lover Handoko Njotokusumo and Ace ride through traffic during their weekend joy ride on a motorcycle.

Recent research led by Takefumi Kikusui at Japan's Azabu University has shown that levels of the chemical spike when humans and their dogs gaze into each other's eyes, mirroring an effect observed between mothers and babies.

In genetics, UCLA geneticist Bridgett vonHoldt made a surprising discovery in 2009: dogs have a mutation in the gene responsible for Williams syndrome in humans -- a condition characterised by intellectual limitations and exceptional gregariousness.

"The essential thing about dogs, as for people with Williams syndrome, is a desire to form close connections, to have warm personal relationships -- to love and be loved," writes Wynne.