Grapevine Domestication: why, how and where?
Serendipitous Inebriation gave us Wine
The wild grapevine (Vitis vinifera subsp. silvestris) is a liana; a plant that naturally climbs up forest trees to reach the canopy where it can produce flowers that will develop into berries. These well-exposed berries are very attractive to birds who transport their seeds further, thus perpetuating the species. We might wonder… why would a Paleolithic man or woman brave the dangers of climbing a tall forest tree to reach those dark red berries that are so attractive to birds but offer so little food value? Serendipitous inebriation might be the answer!
Eno-archaeologist Patrick McGovern* proposed his ‘Paleolithic Hypothesis’ to describe the first event/s of grapevine domestication.
At a time when early humans were organised in hunter-gatherer tribes, it is argued that some Paleolithic man, or even more likely some Paleolithic woman — since men were mostly hunters and women mostly gatherers — was so deeply intrigued by the well-exposed and brightly coloured berries of the wild grapevine that he or she braved the dangers of climbing a tall forest tree to reach them.
Several bunches of grapes were gathered up in a wooden container or a rock crevice. After a few days, under the weight of overlying grapes, some juice would have exuded from the berries at the bottom. A low-alcoholic wine could have been spontaneously produced, with the wild fermentation yeasts that are present on the berries’ skins.
Having eaten all the grapes, this Paleolithic man or woman would have fortuitously tasted this beverage, and a pleasant euphoria would have him or her become obsessed by one single thought: to start again!
Without a proper container, as wine vessels had not yet been created, this ‘Stone Age Beaujolais Nouveau’, as nicknamed by McGovern, had to be drunk quickly before it turned to vinegar.
This began to change about 12,000 to 10,000 years ago with sedentism, the transition from nomadic to permanent settlement that is intimately related to the beginnings of agriculture, a phenomenon known as the ‘Neolithic Revolution’ that propelled the development of dense populations and long-term food storing. These newly settled populations needed to find a way to secure grape supply…
Grapes do have sex, too…
“The Hermaphroditic Hypothesis”: How Domestication was made Possible
I suggest to name the first grape domestication event the ‘Hermaphroditic Hypothesis’, echoing the Paleolithic Hypothesis of the discovery of wine. Botanists usually subdivide Vitis vinifera into two subspecies, the wild grape (Vitis vinifera L. subsp. silvestris), that naturally occurs from Portugal to Tajikistan, as well as along the main continental rivers of western Europe and in northern Africa, and the cultivated Eurasian grape (Vitis vinifera L. subsp. vinifera (also called subsp. sativa)).
The two subspecies do very much look alike, not least because vinifera was domesticated from silvestris by human hand. The most discriminating character between wild and cultivated grapes is flower sex: silvestris is dioecious, which means that all the flowers on the same vine are either male (staminate only) or female (pistillate only), while vinifera is hermaphroditic, with flowers having stamens and pistil.
However, a tiny percentage of silvestris is hermaphroditic, which was undoubtedly the starting point of grape domestication.
In order to secure enough grape supply and avoid the dangers of climbing up trees, some early Mesolithic or Neolithic man or woman decided to cultivate wild grapevines either by sowing seeds or by burying cuttings in the ground, which Vitis vinifera spontaneously does in nature (this is called layering). If a male plant was chosen, the vine would never produce berries and would be quickly abandoned. If a female plant was chosen, the vine would produce berries only if a male plant was in the direct neighbourhood for pollination, otherwise the plant would appear to be sterile and would be abandoned. If a hermaphroditic plant was chosen, grape harvest would be secured each year (berries are usually produced by selfing, which means that the pollen fertilizes the pistil of its own flower!) and the vine would be preserved. It is therefore very likely that grape domestication was made from the circa 2-3% of hermaphroditic wild grapevines that are usually observed in natural populations: this is the Hermaphroditic Hypothesis.
The domesticated vines were then propagated by seed sowing or by cuttings, and those with desirable characteristics such as larger berries, bigger clusters, higher sugar content or better aromas were actively selected for millennia. This has led to the huge morphological diversity observed among the 10,000 grape varieties in existence today, of which around 1,500 are used to make wine...
* In his seminal book ‘Ancient Wine’, 2003.