Plant Domestication and Crop Evolution in the Near East: On Events and Processes

Abstract

Reconstructing the evolutionary history of crop plants is fundamental for understanding their adaptation profile and the genetic basis of yield-limiting factors, which in turn are critical for future crop improvement. A major topic in this field is the recent claim for a millennia-long ‘protracted’ domestication process. Here we evaluate the evidence for the protracted domestication model in light of published archaeobotanical data, experimental evidence and the biology of the Near Eastern crops and their wild progenitors. The crux of our discussion is the differentiation between events or ‘domestication episodes’ and the later following crop evolutionary processes under domestication (frequently termed ‘crop improvement stage’), which are by definition, still ongoing. We argue that by assuming a protracted millennia-long domestication process, one needlessly opts to operate within an intellectual framework that does not allow differentiating between the decisive (critical) domestication traits and their respective loci, and those that have evolved later during the crop dissemination and improvement following the episodic domestication event. Therefore, in our view, apart from the lack of experimental evidence to support it, the protracted domestication assumption undermines the resolution power of the study of both plant domestication and crop evolution, from the cultural as well as from the biological perspectives.

Keywords:

• conscious vs. unconscious selection
• domestication episode
• origin of Near Eastern agriculture

ACKNOWLEDGMENTS

The authors thank Professor Gideon Ladizinsky for many years of learning, inspiration and numerous discussions on the biology of plant domestication. Thanks are due to Professor Paul Gepts for his highly valuable comments on the manuscript. SA and AG acknowledge support by an Israel Science Foundation Bikura grant (no. 1406/05).

Notes

1. Based on the on-line Cambridge, Merriam-Webster and Oxford dictionaries, we herein use the word ‘episode’ to denote the following: A single event; an event that is distinctive; an incident or period considered in isolation. In our discussion herein, the term ‘domestication episode’ is used as opposed to the notion of protracted domesticated process for the origins of crops (Abbo et al., 2011a).