Sheep pick Barack Obama, Emma Watson out of a line-up
Research finds sheep have remarkably well developed facial recognition systems. Tim Wallace reports.
Sheep, for too long maligned by popular expressions implying they are dull, thoughtless creatures, are actually almost as smart as humans when it comes to recognising faces. New research from Cambridge University in the UK indicates sheep recognise faces in a “holistic” manner, with the brain power to process and extrapolate between two-dimensional and three-dimensional facial images.
Aside from these findings making being compared to sheep more palatable, the researchers see the potential to use ovine brains to investigate treatments for neurodegenerative disorders such as Huntington’s disease.
Human appreciation that sheep have superior face-recognition skills isn’t new. There’s a reason the Gospel of John has Jesus observing: “I know my sheep and my sheep know me.”
It has been long thought by shepherds and scientists that sheep can not only distinguish between the faces of their own kind – which many animals can do – but also the individual faces of other species – something of which only select group of animals including horses, dogs and monkeys is capable. This research, however, confirms just how good at it sheep are.
"Anyone who has spent time working with sheep will know that they are intelligent, individual animals who are able to recognise their handlers," says neurobiologist Jenny Morton, who led the Cambridge study. "We've shown with our study that sheep have advanced face-recognition abilities, comparable with those of humans and monkeys.”
To prove that sheep really do recognise individual human faces rather than simply being able to memorise images – in the same way that they have been shown the ability to discriminate between abstract shapes – Morton and her colleagues put eight Welsh Mountain sheep (Ovis aries) through a series of tests.
First, the scientists tested the animals’ ability to recognise humans they had never seen before. The sheep were repeatedly shown photographs of four individuals: former US president Barack Obama, actors Jake Gyllenhaal and Emma Watson, and the popular BBC television presenter Fiona Bruce. Then the sheep were tested to see if they could recognise those four faces from a new perspective (using photographs where the humans’ heads were tilted left or right). Finally, the sheep were tested for their ability to recognise a familiar handler from a photograph.
“We interpret our data as showing that sheep can not only be trained to recognise unfamiliar human faces, but that they can also recognise the face of a person familiar to them from a two-dimensional image,” the Morton and her team conclude in their research paper, published in the journal Royal Society: Open Science.
The paper notes the possibility that the sheep in the experiment having extensive contact with humans might potentially have led to making them human face experts.
“One could also argue that the general domestication of sheep contributes to their abilities to recognise humans,” the scientists write.
“However, the breed of our sheep, Welsh Mountain, is not one of the more easily managed/tamed breeds. Indeed, they are characterised by their ability to survive independently of human support in the harsh environments in mountain areas.”
The researchers see opportunities to use to sheep to investigate human cognitive dysfunctions that lead to impaired face perception. This includes neurodegenerative conditions as well as psychiatric disorders such as autism spectrum disorder and schizophrenia.
“Sheep are long-lived and have brains that are similar in size and complexity to those of some monkeys,” Morton says. “That means they can be useful models to help us understand disorders of the brain, such as Huntington's disease, that develop over a long time and affect cognitive abilities. Our study gives us another way to monitor how these abilities change, particularly in sheep who carry the gene mutation that causes Huntington's disease."