It turns out that the look of mutual recognition between human and dog reflects thousands of years of evolution, a bond programmed into our very body chemistry.

Anyone who owns a dog is familiar with the “gaze”—that hypnotic, imploring stare that demands reciprocation. It can seem to hold a world of mystery and longing, or just pure bafflement at what makes humans tick.

Last spring a research team in Japan discovered that both species release a hormone called oxytocin when they look into each other’s eyes—the same hormone released when a human mother beholds her baby.What’s more, the Japanese study showed that higher levels of oxytocin were released during that gaze than during petting or talking. It seems that for dogs, at least where humans are concerned, eyes really are windows to the soul.

“It’s a very compelling study, that even on a chemical basis we get this kind of biological impulse to bond, and animals have the same impulse to bond with us,” says University of Alberta anthropologist Robert Losey, who studies the historical relationship between dogs and humans.

But where does that unique symbiosis begin, one that has long involved even the sharing of parasites and certain diseases? According to Losey, the biochemical bonding impulse is only one part of the story. His own research is focused on teasing out the cultural forces over time that have made dogs and humans such a good fit.

Source: Researcher explores close prehistoric relationship between humans and dogs