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Saturday, June 10, 2023

The domestication of vitis vinifera: The physical environment

According to Dong, et al., two variants of the wild grape vitis sylvestris were simultaneously domesticated in the Caucasus and Western Asia resulting in two variants of vitis vinifera. The Caucasus-sourced vitis vinifera flourished on both sides of the Caucasus Mountains, and even extended into the Carpathian Basin, but had no impact beyond this limited geographical area. The Western Asia domesticate, by a process of elimination, must be the source variety for the bulk of the world's wine grapes. I will explore the environment wherein this variety was domesticated as well as the people who most likely brought sylvestris to heel. I examine the physical environment in this post.

Vitis sylvestris was domesticated in the early part of the Holocene. The physical environment in Western Asia during this time period is illustrated in the chart below.


Dong, et al., did not specify the location of the domestication center within Western Asia but an eyeballing of their placement of the center on the map would seem to place it within the confines of the region called The Levant. The coverage of the Levant is illustrated in the rightmost map below and the blue arrow illustrates the relationship between that region and the Western Asia Domestication Center.


According to Bar-Yosef and Valla, "lines of evidence demonstrate that cold, wet conditions" dominated in The Levant in the late Pleistocene. This was followed by a dry spell in the transition period and a steady increase in arboreal pollen. An increase in humidity is observed for the in the Early Holocene "in the Middle Euphrates Valley in Northern Syria and from the Lower Jordan Valley" (Bar-Yosef and Valla). The paleoclimatic record shows the following (Bar-Yosef):
  • Late Glacial Maximum (20,000 - 14,500 B.P.)
    • Entire region cold and dry
    • Hilly coastal areas enjoyed winter precipitation and were covered by forests
  • 14,500 - 12,800 B.P.
    • Precipitation slowly increased over the entire region beginning at 14,5000
    • More rapid increase from 13,500 B.P. to 13,000
    • Rate peaked around 13,500 in the southern Levant
  • Younger Dryas (12,800 - 11,600 B.P.)
    • Rate of rainfall decreased
  • 11,300 B.P.
    • Increased rainfall returns
      • Very wet early Holocene in the northern Levant and Anatolia
      • Did not reach the previous peak in central and southern Levant
  • Gradual rise in sea level
    • Post the Late Glacial Maximum and until the mid-Holocene
    • Reduced the flat, sandy coastal plain of the Levant by a stretch 5 - 20 km wide and 500 km long.
During the Holocene, The Levant was characterized by a variety of landscapes running between the southern flanks of the Taurus Mountains of Turkey and the Sinai Peninsula:
  • Narrow coastal plains
  • Two parallel continuous mountain ranges with a rift valley in between
  • An eastward-sloping plateau dissected by many eastward-running ravines.
There was marked seasonality, with cold, rainy winters and hot, dry summers being the norm. Two annual patterns of winter storm tracks were observed:
  1. Humidity from the Mediterranean flowed to the southern Levant
  2. Storms arrive from northern Europe and turn to the northern Levant.
There were three vegetational zones (Bar-Yosef):
  • Where annual precipitation exceeded 400 mm/year, Mediterranean woodland and open parkland 
    • Oak-dominated parkland and woodland provided the"highest biomass of food available to humans." Dense oak forests (> 800 mm/year rainfall) maintain a lower biomass than the open parklands
  • Where precipitation was < 400 mm/year, shrub land and steppic vegetation 
  • Arid-type vegetation.

Effect of the Physical Environment on Vitis Sylvestris/Vitis Vinifera
Environmental conditions have marked effects on grape development today and it is quite likely that grapes reacted similarly in times past. It is likely that vitis sylvestris exhibited different characteristics in the cold of the Pleistocene than did vitis vinifera in the warming period of the Early Holocene. As a matter of fact, the last glacial cycle (115,000 - 11,700 years ago) was the scene of one of the most severe vitis sylvestris bottlenecks, driving worldwide population down to between 10,000 and 40,000 vines.

The warming period began with the retreat of the glaciers and the changes in the physical environment highlighted in map 1 above. Just the mere fact of the warming would have positive effects on the grapevine and its product. Warmer temperatures would lead to riper, more palatable grapes (Remember that grapes in this early period were used as a food source as opposed to a beverage.). This riper, more palatable fruit would stand in stark contrast to the potentially harder, greener product that would have been the norm in the colder, drier Pleistocene.

Increased humidity would have led to more vigorous vines and plumper fruit. Grapes would not only be more palatable, they would also be more substantial.

The forest expansion that resulted from the warming would have also been beneficial to vitis vinifera. The grapevine is a climber and more trees represented more growth/spread opportunities for the population. 

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In my next post I will explore the culture that most likely domesticated the grapevine.

Bibliography
Bar-Yosef, O., The Natufian Culture in the Levant, Threshold to the Origins of Agriculture, Evolutionary Anthropology.
Bar-Yosef, O., and F. Valla, The Natufian Culture and the Origin of the Neolithic in the Levant. Current Anthropology 31(4) January.
humanpast.net, Food around 11,000 BC.

©Wine -- Mise en abyme

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