A brief history of the origin of domesticated date palms

The study of the origins of crops is of interest from both a fundamental evolutionary understanding viewpoint, and from an applied agricultural technology perspective. The date palm (Phoenix dactylifera L.) is the iconic fruit crop of hot and arid regions of North Africa and the Middle East, producing sugar-rich fruits, known as dates. There are many different cultivars each with distinctive fruit traits, and there are many wild Phoenix species too, which in total form a complex of related species. The understanding of plant domestication involves multiple disciplines, including phylogeography, population genetics and archaeology. In the past decade, they have prompted new discoveries on the evolutionary history of date palm, but a complete understanding of its origins remains to be elucidated, along with the genetic architecture of its domestication syndrome. In this chapter, we review the current state of the art regarding the origins of the domesticated date palm. We first discuss whether date palms are domesticated, and highlight how they diverge from their wild Phoenix relatives. We then outline patterns in the population genetic and archaeobotanical data, and review different models for the origins of domesticated date palms by highlighting sources of evidence that are either consistent or inconsistent with each model. We then review the process of date palm domestication, and emphasize the human activities that have prompted its domestication. We particularly focus on the evolution of fruit traits.