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Ethologist Veronica Malgeri from the University of Pisa and her colleagues set out to explore how thousands of years of selective breeding have shaped dogs\u2019 facial expressions. The team analyzed video recordings to observe how many facial muscles dogs use when displaying a relaxed, open-mouth expression \u2014 a universal signal of playful mood.<\/p>\n\n\n\n
The researchers studied videos of 210 dogs representing 29 popular breeds and found that all dogs \u201csmile,\u201d though they do so in different ways. Wolf-like breeds, for example, can use up to three times more facial muscles for communication than other dogs.<\/p>\n\n\n\n
\u201cPoodles, German Shepherds, Basset Hounds, and Rottweilers used a greater number of facial muscle movements, creating more complex and expressive faces,\u201d explains Dr. Malgeri. \u201cBeagles and Jack Russell Terriers, on the other hand, showed a simpler version of the same signal.\u201d<\/p>\n\n\n\n
Dogs with flat faces, such as Pugs and French Bulldogs, have more limited facial mobility due to skull structure, yet they do not lag far behind other breeds.<\/p>\n\n\n\n
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The study also found that Huskies, Labrador Retrievers, Borzois, and Cocker Spaniels tend to look less cheerful, while Australian Shepherds, Beagles, Shar-Peis, and Jack Russell Terriers appeared the saddest.<\/p>\n\n\n\n
Researchers emphasize that facial expressiveness does not equal actual happiness. A German Shepherd is not necessarily happier than a Beagle \u2014 its \u201csmile\u201d is simply more noticeable to humans.<\/p>\n\n\n\n
\u201cAs with humans, raised mouth corners and wrinkles around the eyes signal happiness,\u201d says Dr. Malgeri. \u201cWhen we see similar facial cues in animals, we instinctively interpret them as joy.\u201d<\/p>\n\n\n\n
She also notes that playful facial expressions are primarily meant for communication with other animals. The study showed that dogs even use them when playing with horses. \u201cHorses react to these signals almost the same way humans respond to contagious laughter,\u201d Malgeri adds.<\/p>\n\n\n\n
Humans domesticated wolves between 20,000 and 40,000 years ago, and since then dogs have become one of humanity\u2019s most successful partnerships.<\/p>\n\n\n\n
\u201cDomestication likely happened passively,\u201d explains Dr. Krishna Virama, associate professor at Stony Brook University. \u201cMore docile wolves lived near humans, feeding on scraps. Over time, a mutually beneficial relationship formed, leading to the emergence of hundreds of breeds.\u201d<\/p>\n\n\n\n