Sheep differentiate individual human faces shown in photos

A new study from the University of Cambridge in England published in the online journal “Royal Society Open Science” reveals that sheep can recognize familiar and unfamiliar human faces from photographs.

It has already been proven that sheep can recognize other sheep as well as familiar humans, such as their handlers. However, this newfound ability to recognize unfamiliar human faces from photographs is groundbreaking.

At first, the study involved training the sheep to approach certain images. Sheep were given food depending on the person whose image they were looking at. They were also given an error or timeout signal in the form of an audio signal if they did not choose the right photo on time. This training came in three parts – choosing a face instead of a black screen, choosing a face instead of the picture of a household item and choosing the correct familiar face instead of another face. After this was ingrained in the sheep’s brain, the signals were then removed and the sheep had to pick the correct familiar face from a set of two faces.

Around 75 percent of sheep,  a statistically significant amount, recognized the familiar face even when the face was tilted to the right or to the left. One of the trial sessions involved a twist on the original program. In this twist, the sheep were presented with three pictures of the handler and three pictures from a set of preselected faces. Sheep chose their handlers 72 percent of the time instead of choosing the less familiar faces that the sheep had been trained to go toward before. This was particularly interesting, as it showed that the handler had developed a connection with sheep even though there was no reward of food or punishment, and there were no audio cues associated with the handler.

This study shows that sheep have advanced facial recognition skills, with their skill being comparable to  humans and monkeys. Facial recognition skills are some of the most important skills that social animals need to function. Facial recognition systems are imperative for people who wish to interact with a great number of people, or even within their close circles. Detecting faces can even be as effective as the use of spoken language or body language when it comes to communication. This is why one of the indications of the maturity and growth of a baby is that the baby recognizes the facial cues that it needs to be able to discern for the rest of their life.

In the case of humans, a human’s brain circuitry is constantly decoding the emotions of others based on extremely subtle facial clues. The ability to detect these microscopic changes in facial musculature often goes unnoticed as it is just taken as any other part of peoples’ everyday lives. The true effect of the skill of detecting faces is revealed when looking at people who cannot do so. Two such cases are people with Asperger’s syndrome, a disorder that is characterized by poor social skills and a fixation with one subject, or Huntington’s disease, a genetic condition that destroys nerve cells.

Asperger’s syndrome is not fully understood, but what scientists do know is that it is associated with a recent evolutionary part of the brain – the dorsolateral prefrontal cortex. This is an area of the brain that experiences an extended period of maturation which lasts until adulthood. Scientists are also aware of the symptoms of Asperger’s syndrome. Other neurological disorders, however, are not as well understood. Huntington’s disease is one of those disorders. While scientists may know of the symptoms of Huntington’s, they can learn more about the disease by probing further into the depths of the neurological bases of human facial recognition systems by assessing the brains of sheep.

“Sheep are long-lived and have brains that are similar in size and complexity to those of some monkeys. 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,” according to Jennifer A. Morton, a professor of neurobiology at the University of Cambridge and director of studies in Medicine and Veterinary Medicine at Newnham College.

Morton and her team have also taken this step forward themselves, by beginning research on genetically modified sheep that carry the mutation for Huntington’s disease. This research allows for further insight into the disease and aid in potentially developing  treatments for Huntington’s disease. This research can also be applied to other diseases that affect innate facial recognitions systems.