They are bred stupid. Around here, whenever an old ewe (is this the correct term for a female sheep?) shows some intelligence it is promptly put down. The intelligent ones turn up now and then and they are shrewd enough to evade the herders, always finding paths and passes where humans can't go. They also always become leaders of the flock which then becomes wild very fast.Having lived on a farm, I can tell you that cows are perhaps the most stupid creatures on this planet....sheep come a close second!
Regards,
Jay.
Sometimes they are useful, though as they are not as likely to die in blizzards or avalanches, but most often they are a pain the ass.