By Jane J. Lee, National Geographic

Science is still undecided on the matter, although evidence in favor of the idea is stacking up.

Now, a new study has found that dogs are able to tell the difference between happy and angry human facial expressions.

Biologist Corsin Müller of the University of Veterinary Medicine in Vienna, Austria, and colleagues tested 11 dogs — including border collies, a fox terrier, a golden retriever, a German shepherd, and some mutts — using a touchscreen. The scientists trained the dogs to touch either a happy face or an angry face for a treat.

They presented dogs with either the top half or the bottom half of the faces to ensure the animals weren’t just responding to a smile or the baring of teeth. Emotions show on all parts of a human face, not just the mouth, says Müller, whose study was published Feb. 12 in the journal Current Biology.

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