6. Domestication rates in wild-type wheats and barley under primitive cultivation

Abstract

Man's first cereal crops were sown from seed gathered from wild stands, and it was in the course of cultivation that domestication occurred. This paper prcsents thr preliminary rrsults of an experimcntal approach to the measurement of domestication rate in crops of wild-type einkorn wheat exposed to primitive systems of husbandry. The results indicate that in wild-type crops of einkorn, emmer and barley (a) domestication will have occurred only if they were harvested in a partially ripe (or near-ripe) state using specific harvesting methods; (b) exposure to shifting cultivation may also have been required in somr cases; and (c) given these requirements, the crops could have become completely domcsticated within two centuries, and maybe in as little as 20–30 years without any form of conscious selection. This paper (1) considers the possible length of delays in the start of domestication due to early crops of wild-type cereals lacking domestic-type mutants; (2) examines the combination of primitive husbandry practices that would have been necessary for any selective advantage to have been unconsciously conferred on these mutants; (3) considers the state of ripeness (at harvest) necessary for crops to be able to respond to these selective prcssures; (4) outlines field measurements of the selective intensities (selection coefficients) which arise when analogous husbandry practices are applied experimentally to living wild-type crops; (5) summarizes the essential features of a mathematical model which incorporatcs these measurements of selection coefficients and other key variables, and which describes the rate of increasc in domestic-type mutants that would have occurred in early populations of wild-type cereals under specific combinations of primitive husbandry practices; (6) considers why very early cultivators should have used that combination of husbandry methods which, we suggest, unconsciously brought about the domestication of wild wheats and barley; and (7) concludes by considering whether these events arc likely to have left recognizable traces in archaeological remains.