Primitive breeds of sheep and goats, such as the Ronaldsay sheep of Orkney, could be in danger of disappearing with the present rapid decline in pastoral farming. The authors, both members of the Department of Forestry and Natural Resources in Edinburgh University, point out that, quite apart from their historical and cultural interest, these breeds have an important part to play in modern livestock breeding, which needs a constant infusion of new genes from unimproved breeds to get the benefits of hybrid vigour. Moreover these primitive breeds are able to use the poor land and live in the harsh environment which no modern hybrid sheep can stand.