↑ A. Sherratt, Plough and pastoralism: aspects of the secondary products revolution, in Pattern of the Past: Studies in honour of David Clarke, edited by I. Hodder, G. Isaac and N. Hammond (Cambridge University Press: Cambridge 1981), pp. 261–305. ↑ Haskel J. Greenfield, The origins of milk and wool production in the Old World: A zooarchaeological perspective from the Central Balkans, Current Anthropology vol.