Walnuts and the First Forest Farms - AramcoWorld article
Combining genetic analysis with ethno-linguistic data, researchers from Purdue and the Rome-based Italian National Research Council (CNR) discovered a significant association between the genetic structure of walnut populations and the evolution of languages. Genetic structures even converged between Tashkent and Samarkand in Uzbekistan, where the northern and central routes of the Northern Silk Road came together. This strongly suggested that traders carried walnuts east and west through Turkey, Iran and the Trans-Caucasus to Central Asia. It is likely they saved walnuts from the best trees, selecting those with the characteristics to produce high-quality nuts and possibly wood, and purposely planted them as long-term “crop investments.” This puts walnuts among the first known examples of planned afforestations.