A group of sheep is called a flock. Sheep follow each other in basically the same way all the time, so there are special names for the different roles sheep play in a flock. The sheep that is farthest away from the others is called the outlier, a word that is also used in statistics. This sheep is willing to go out farther away from the safety of the flock to graze, but takes a chance that a predator like a wolf will attack it first, because it is alone. Another sheep, the bellwether, which never goes first but always follows an outlier, is the one that signals to the others that it is safe to go that way. When it moves, the others will also move. Tendency to be outliers or to be bellwethers, or stick in the middle of the flock, seems to stay with a sheep its whole life. There might be genes that make them repeat this role behaviour.