Over time, selective breeding reduced the diameter of the coarse thick hair in the outer fleece, while at the same time making the smooth inner hair thicker, with a diameter of some 15 micrometres (thousandths of a millimetre). Most early archaeological textile remains have a fibre of a diameter of around 20 micrometers, as is normal today. New dyeing techniques developed in the Middle East around 1000 BC triggered an improvement in the selective breeding of white wool sheep. There were also improvements in shearing tools, many of which have been found in archaeological sites dating back from the end of the Iron Age and in Roman sites all over Europe. These were rudimentary scissors formed by two facing blades linked by a steel arch that functioned as a spring. Fabric and sheep leather archaeological remains dating from the same period display a change in the wool structure. Likewise, Roman age fabric found in archaeological sites also shows how the fleece was being transformed.

Fine and medium fine grades of wool became increasingly important in Europe during the Middle Ages. In the Mediterranean area, and in Spain in particular, production using sheep which produced finer grades of wool led to the rise in prominence of the Merino, the breed which produced the highest quality of all. Until the last third of the eighteenth century, the raising of the Merino was controlled by the Honrado Concejo de la Mesta (1273-1837),making it effectively a Spanish monopoly, its export abroad was banned; their flocks would alter the landscape of the plateau and the cattlemen reached sufficient importance to influence the political history of the nation. Present-day Merino livestock worldwide originates almost in its entirety from sheep originally bred in Spain and exported at this time. Subsequent development, taking place over a little less than a century, saw the introduction of the Spanishbred Merino into a range of western (France, Great Britain, Germany and the USA) and southern-hemisphere (Argentina, South Africa, New Zealand and Australia) countries, giving rise to a variety of new breeds: the Rambouillet, Negretti, American Merino, Vermont, Delaine and the Australian Merino. The enormous growth of grassland combined with the introduction of these new varieties would lead to a historically unprecedented growth in the mass of livestock and herds. One only has to recall that of Australia – the world’s number one producer of wool – it is said that for every hundred sheep, there is but one person.