Everyone knows that dogs are a man's best friend - and now scientists have shown they can read our faces.
Researchers in Vienna have established that dogs are able to tell the difference between angry and happy human expressions.
They say this is the first credible evidence of any non-human animal being able to recognise the countenance of another species.
"Our study demonstrates that dogs can distinguish angry and happy expressions in humans.
"They can tell that these two expressions have different meanings, and they can do this not only for people they know well, but even for faces they have never seen before," said Ludwig Huber, of the University of Veterinary Medicine Vienna.