Despite having a comparable brain size to other highly evolved animals, sheep have been historically perceived as unintelligent and were therefore not considered to be good animal models for studying diseases that affect learning and memory. However, new research recently published in the journal PLoS ONE shows that sheep are indeed smarter than previously believed. The researchers are hopeful the animals will prove useful for research into diseases that impair the cognitive abilities of patients, such as Huntington's disease (HD) and Alzheimer's disease. Sheep are quadrupedal, ruminant mammals typically kept as livestock. Like all ruminants, sheep are members of the order Artiodactyla, the even-toed ungulates. Although the name "sheep" applies to many species in the genus Ovis, in everyday usage it almost always refers to Ovis aries. Numbering a little over one billion, domestic sheep are also the most numerous species of sheep.
"A new line of genetically modified sheep developed by researchers in New Zealand and Australia which carries the defective gene for HD has given us some unique opportunities to research treatments for this debilitating disease," said Professor Jenny Morton, a University of Cambridge researcher who specialises in HD. "However, if we are going to test the cognitive function in the HD sheep, first we need to understand how the brain works in a normal sheep."
The scientists posed a series of challenging tests similar to ones used to assess cognitive impairments of humans suffering from HD. The tests for the sheep involved making choices that were cued by different colored or shaped objects, with feed as an incentive. These were each mastered in turn by the sheep. For example, in the first and easiest trial the sheep was presented with a blue bucket containing food and an empty yellow bucket. After a few trials they went automatically to the blue bucket.
Previous research has shown that sheep not only have good memories for faces. This study shows that they also can discriminate color and shape as separate dimensions.
Sheep are frequently thought of as extremely unintelligent animals. A sheep's herd mentality and quickness to flee and panic in the face of stress often make shepherding a difficult endeavor for the uninitiated.
Despite these perceptions, a University of Illinois monograph on sheep found them to be just below pigs and on par with cattle in IQ, and some sheep have shown problem-solving abilities; a flock in West Yorkshire, England allegedly found a way to get over cattle grids by rolling on their backs, although documentation of this has relied on anecdotal accounts. In addition to long-term facial recognition of individuals, sheep can also differentiate emotional states through facial characteristics. If worked with patiently, sheep may learn their names, and many sheep are trained to be led by halter for showing and other purposes. Sheep have also responded well to clicker training in the past.
For further information: http://www.admin.cam.ac.uk/news/dp/2011022101