This is how the vine explains the coevolution of species

There domestication of plants and animals is at the basis of the Neolithic revolution, i.e. of that process which led both to the first demographic explosion of our species, and to the flowering of the first historically documented civilizations as linked to well-defined territories, to more advanced cultural technologies and productions and, ultimately , to the way of life that still characterizes us today. The process of domestication is always better recognized as dominated by the interweaving of cultural factors and bidirectional genetic selectionwhich is why it is now commonly recognized as part of the Darwinian coevolution of related species.

A beautiful demonstration of this complexity, together with that of the power of the most modern methods of investigation, can be found in an article published in the latest issue of Science, dedicated to the grapevine domestication process. By incorporating the effects of glacial oscillations on the biogeographic distributions across Eurasia of the wild progenitor of our domesticated grapevine, i.e. Vitis vinifera ssp. sylvestris, the researchers identified on genomic basis two separate processes of domestication starting from two distinct populations of wild grapevine in the Near East and in the southern Caucasus, regions isolated from each other during the last glacial period.

Although the domestication of the South Caucasus is associated with early winemaking, the origin of wine in Western Europe is associated with cross-fertilization (introgression) between wild Western European populations and domesticated grapes native to the Near East that were initially used as a food source. Specifically, using 2,448 genomes from grapevine samples collected at 23 institutions in 16 countries, the researchers were able to determine that glaciations must have split eastern and western wild grape populations – distinct and locally adapted varieties – around half a million years ago. does. The last glacial advance saw the further split of the eastern landrace into two groups, each of which gave rise to a different domestication process, in the southern Caucasus and in the Near East. Despite being separated by more than 1,000 kilometers, the two domestication processes appear to have occurred concurrently about 11.5 ka, simultaneously with the initial emergence of cereals. This is consistent with a model in which human communication and exchange networks over comparable distances, which have been documented since 20,000 years ago, rapidly spread the vine domestication skills in favorable environments, even very distant from each other.

The domestication of the southern Caucasus had a limited diffusion and a very small influence, contrary to what happened in the Near East, from which four main lines of cultivated vines were established in Europe; the dates of the formation of these four original European varieties correspond precisely to the diffusion of Neolithic culture and populations in Europe. Furthermore, since in both domestication processes selective effects are observed on the same genes, it is so possible that humans have favored the distant transport of seeds and plants of a certain type with the desired characteristics, so much so that those traits were present everywhere in different and equivalently selected types in distant places.

Then there is another, fascinating aspect that has emerged from the latest research.

In the vine, after domestication and probably thanks to continuous crossbreeding with wild varieties, adaptations to the environment associated with water stress and resistance to disease have been acquired. However, these adaptations, useful for growers in drier areas such as the Middle East and on the Mediterranean coasts, also correspond to traits that compromise the edibility of the grape. Compared to table grapes, wine grapes are smaller and thick-skinned and have a lower sugar content: these are characteristics more similar to those of wild grapes, which make the fruit more suitable for winemaking and less palatable for direct consumption.

Thus, it is possible that, during the expansion caused by man in coastal areas, or in any case drier and more arid than those in which wild vines thrive better, which are precisely those typical of the first great human civilizations where it spread agriculture, traits that tended to favor the production of wine over the consumption of fresh fruit were naturally selected; the production of wine, that is, could have gradually acquired more importance because in the areas of human expansion the best vines were those with small fruit, thick skin and greater tolerance of water stress.

And it is precisely in this that the element of the domestication process that I introduced at the beginning can be clearly seen: human migrations and the change in life habits associated with the Neolithic have favored a type of domesticated plant over others, because the environments in which these phenomena occurred were such as to couple a factor of natural selection to the crop selection operated by the first farmers.

Once again, the reconstruction of the double domestication of life represents a splendid example of those very ancient stories that DNA can tell us, in a new era for archeology and paleontology in which very modern techniques can finally be addressed to questioning the past.