A UK study shows that sheep placed in a stressful situation find the pictures
of familiar sheep more comforting than other similar images.
A UK study shows that sheep placed in a stressful situation find the pictures
of familiar sheep more comforting than other similar images.
"Sheep are much like us in that they recognise each other’s faces and
use visual cues to judge emotional state from a facial expression," said
Keith Kendrick, who led the study at the Cognitive and Behavioural Neuroscience
Laboratory of Cambridge University. "They are very sensitive to social
isolation and we wanted to see if looking at an 'attractive' sheep would reduce
separation anxiety."
Kendrick and colleagues tested levels of the stress hormones, adrenaline and
cortisol, in more than 20 sheep, before separating each animal from the flock
and leaving each individal for a period of 15-minutes in an isolated room with
four large images of inverted triangles, representing a sheep's face. The images
were then replaced with either four identical photographs of a life-sized
sheep's face of the same breed, or images of a goat's face. The inverted
triangles remained in the control group. Blood samples were obtained 30 minutes
later.
Significant differences in heart rate and stress hormone levels were found at
the end of each session, depending on the image shown to the sheep. The sheep
that were shown inverted triangles remained stressed, with heart rates of 100
beats per minute and elevated adrenaline and cortisol blood levels. The sheep
that were shown a goat face had very slightly reduced heart rate and blood
hormone levels, whereas those shown a sheep face had heart rates of 80 beats per
minute and normal blood hormone levels.
X-ray images of the temporal cortex of the sheep's brains, which is concerned
with emotional response, and gene markers were used to highlight areas of high
activity.
"The sheep that had been shown only the inverted triangle showed high
activity in the regions relating to fear, anxiety and stress, but low activity
in the areas dealing with face recognition and emotional control. But those
shown a face had evidence of high activity in the regions relating to face
recognition and emotional control and low activity in the stress and fear and
anxiety regions," said Kendrick.
These findings, published in the Proceedings of the Royal Society: Biological
Sciences (DOI: 10.1098/rspb.2004.2831), point to a simple way of reducing
separation anxiety in animals and humans. "It shows that if agricultural
animals need to be isolated during transportation, showing them a familiar face
could calm them. And children suffering separation anxiety could carry a photo
of a loved one," he said.