Wool

Abstract

Sheep have both hair, referred to as kemp, and wool and the wild sheep first domesticated had more hair than wool, a feature that selective breeding has inverted. The first evidence of such selective breeding is from Iran around 6000 B.C. with the earliest wool clothing dating from to 3000–4000 B.C.Wool has a protective coating composed of hygroscopic protein (keratin) fibers created in the sheep’s skin. The fibers themselves are dead. Wool is distinguished from fur in that it grows in clusters or staples. Also, unlike fur, which grows to a fixed length and stops growing, wool grows continuously. This continuous growth is a trait shared with the hair on sheep. In fact, some sheep, typically those bred in warmer climates, grow more hair than wool. Hair, is also a protein fiber composed largely of keratin.