New Study Says Humans Are , Responsible for Puppy Dog Eyes.<br />Are you head over heels for the <br />sweet and soulful "puppy dog" <br />eyes looking up at you?.<br />Naturally, many of us are suckers <br />for our begging pups, but dogs weren't always so irresistibly sweet.<br />A recent study has found that "puppy dog" eyes are a result of breeding that started nearly 33,000 years ago.<br />Dogs are unique from other mammals in their reciprocated <br />bond with humans which <br />can be demonstrated <br />through mutual gaze ... , Anne Burrows, professor Rangos School of <br />Health Sciences at Duquesne University, via CNN.<br />... something we do not observe between humans and other domesticated mammals such as horses or cats. , Anne Burrows, professor Rangos School of <br />Health Sciences at Duquesne University, via CNN.<br />Throughout the domestication process, humans may have <br />bred dogs selectively based <br />on facial expressions that <br />were similar to their own. , Anne Burrows, professor Rangos School of <br />Health Sciences at Duquesne University, via CNN.<br />Throughout the domestication process, humans may have <br />bred dogs selectively based <br />on facial expressions that <br />were similar to their own. , Anne Burrows, professor Rangos School of <br />Health Sciences at Duquesne University, via CNN.<br />Dogs have more "fast-twitch" facial muscles than their genetic cousin, the wolf.<br />Dogs have more "fast-twitch" facial muscles than their genetic cousin, the wolf.<br />Researchers say these muscles allow them to mimic the facial expressions of humans.<br />Over time dog muscles could have evolved to become 'faster,' further benefiting communication between dogs and humans. , Anne Burrows, professor Rangos School of <br />Health Sciences at Duquesne University, via CNN.<br />Presented at the American Association for Anatomy's annual meeting, the study analyzed the facial muscles of domesticated dogs and wolves.<br />Researchers say they've found <br />wolves have lower percentages of <br />fast-versus slow-twitch fibers.<br />Slow-twitch fibers in the face of <br />wolves are beneficial to their howl.<br />Fast-twitch fibers in the face of domesticated dogs benefit communication with humans via short, fast barks and varied facial expressions.<br />These differences suggest <br />that having faster muscle <br />fibers contributes to a dog's <br />ability to communicate <br />effectively with people. , Anne Burrows, professor Rangos School of <br />Health Sciences at Duquesne University, via CNN
