Evolution and Domestication of Rye

Abstract

More than 12,000 years ago, with the beginning of the Neolithic Age, one of the most fundamental innovations in human history took place: the beginning of agriculture. The plants and animals that became an indispensable aspect of human life began to differ more and more from their wild relatives, and in the course of time, adaptive traits advantageous for living together with humans were fixed. The history of cultivated rye (Secale cereale subsp. cereale) has long been mysterious, and many theories have been put forward as to its origin. The putative wild progenitor Secale cereale subsp. vavilovii still occurs in Southwest Asia, as do the close relatives of rye, wheat and barley. But in contrast to the latter two species, rye was not used as a cereal crop until the European Bronze Age, several millennia after start of the Neolithic revolution. Hence, it is not among the founder crops of agriculture. Archaeobotanical studies, genetic kinship analyses as well as the cultural history and etymology support the hypothesis of a secondary domestication origin from a weed in wheat and barley fields. In northern and central Europe, its exceptional winter hardiness and its tolerance to grow on poor soils may have enabled it to be grown as a grain crop in its own right. Yet still, in some regions of the world, e.g. Southwest Asia, rye is considered a weed growing among other cereals. In this chapter, we review the current knowledge of the taxonomy of the small genus Secale, the basics of the Neolithic transition and the domestication of cereals, as well as the peculiarities of the cultural history of rye as a secondary domesticate collating evidence from multiple disciplines.