Sheep have demonstrated a celebrity-spotter's ability to recognise faces of famous people, including former US President Barack Obama - according to new research by the University of Cambridge.
Among other faces the sheep could pick out are Harry Potter star - Emma Watson, Jake Gyllenhaal and Fiona Bruce.
But it is more than just a neat trick - the face recognition ability of sheep could be used to investigate Huntington's disease and other human brain disorders that affect mental processing, said the researchers.
One symptom of Huntington's is an impaired ability to recognise facial emotion. The animals were already known to respond to familiar faces, both of other members of their own species and humans.
In the new study scientists showed how the animals could be taught to recognise screen-shot images of celebrity faces using food rewards. They were even able to identify faces seen from an angle with about the same success rate as a human.
Researchers also discovered that sheep can recognise images of their human handlers without any previous training.
Shown a portrait of their handler alongside that of an unfamiliar person, they did a "double take" before approaching the face they knew.
Lead scientist Professor Jenny Morton, from Cambridge University, said: "Anyone who has spent time working with sheep will know that they are intelligent, individual animals who are able to recognise their handlers. "We've shown with our study that sheep have advanced face-recognition abilities, comparable with those of humans and monkeys."
The team trained eight sheep to recognise the faces of four celebrities from photographic images displayed on computer screens. Placed in a special pen, each animal in turn was shown two images of human faces, one of them the "target" celebrity. A reward of cereal pellets was dispensed when a sheep crossed an infra-red beam in front of the celebrity image. If it approached the wrong image, a buzzer sounded and no reward was given.
After training, the sheep were put in the pen again to test their ability to recognise celebrity faces previously associated with food rewards. They correctly chose the learned celebrity face eight times out of 10.
When the experiment was repeated with the portraits displayed at an angle instead of face-on, the sheep's performance dropped, but only by about 15%. This is on a par with the ability of humans to recognise partially seen faces.
In a last test, the sheep were shown photos of their handlers interspersed randomly in place of the celebrity. The animals typically spent two hours a day with the handlers and were very familiar with them. Seven times out of 10, the sheep chose the face of their handler over that of a stranger, despite no prior food-association training. They also displayed peculiarly human behaviour when deciding between the two images. Seeing a photograph of their handler for the first time, the sheep literally did a "double take", said the researchers whose findings appear in the Royal Society journal, Open Science.
The team has started studying sheep genetically modified to carry the mutation responsible for the devastating disease that affects mood, personality, memory, and muscle control.