The origin and spread of olive cultivation in the Mediterranean Basin: The fossil pollen evidence

Abstract

Olive ( Olea europaea L.) was one of the most important fruit trees in the ancient Mediterranean region and a founder species of horticulture in the Mediterranean Basin. Different views have been expressed regarding the geographical origins and timing of olive cultivation. Since genetic studies and macro-botanical remains point in different directions, we turn to another proxy – the palynological evidence. This study uses pollen records to shed new light on the history of olive cultivation and large-scale olive management. We employ a fossil pollen dataset composed of high-resolution pollen records obtained across the Mediterranean Basin covering most of the Holocene. Human activity is indicated when Olea pollen percentages rise fairly suddenly, are not accompanied by an increase of other Mediterranean sclerophyllous trees, and when the rise occurs in combination with consistent archaeological and archaeobotanical evidence. Based on these criteria, our results show that the southern Levant served as the locus of primary olive cultivation as early as ~6500 years BP (yBP), and that a later, early/mid 6th millennium BP cultivation process occurred in the Aegean (Crete) – whether as an independent large-scale management event or as a result of knowledge and/or seedling transfer from the southern Levant. Thus, the early management of olive trees corresponds to the establishment of the Mediterranean village economy and the completion of the ‘secondary products revolution’, rather than urbanization or state formation. From these two areas of origin, the southern Levant and the Aegean olive cultivation spread across the Mediterranean, with the beginning of olive horticulture in the northern Levant dated to ~4800 yBP. In Anatolia, large-scale olive horticulture was palynologically recorded by ~3200 yBP, in mainland Italy at ~3400 yBP, and in the Iberian Peninsula at mid/late 3rd millennium BP.

EST–SNP Study of Olea europaea L. Uncovers Functional Polymorphisms between Cultivated and Wild Olives

“…The high genetic variability of cultivated olive [8][9][10][11][12] (mainly related to its allogamy), the lack of turnover with modern cultivars, a remarkable tree longevity, and the capacity to survive out of managed cultivation, allowed it to spread over a wide range of environments [13][14][15][16]. Inside this diversified scenario, the debate on olive domestication and the contribution of oleasters and related subspecies to this process, is still open and controversial [17][18][19][20][21][22]. Some recent analyses suggest that the olive tree domestication occurred in the Levant (Syrian-Turkish) area, followed by secondary diversifications in two opposite directions, to the west side across the shores of the Mediterranean [13,[23][24][25] and up to the east in the Iranian plateau [16,26,27].…”

Early production of table olives at a mid-7th millennium BP submerged site off the Carmel coast (Israel)

“…Indeed, previous results showed that the wild/feral trees we sampled, are genetically distinct from cultivated olives 10 . However, given the relatively late date of the Hishuley Carmel site, the distinct rise in percentages of olive pollen documented in the region at this time 22 , 23 , coupled with the morphometric variability found in the investigated ancient pits, it seems that the olives from the Hishuley Carmel and Kfar Samir sites were collected from wild trees. However, the possibility that they originated from early cultivated trees cannot be ruled out.…”

“…The radiocarbon ages, date the Hishuley Carmel structures used to prepare table olives to the first half of the 7th millennium BP, 6,700–6,500 years ago, placing them in the Middle Chalcolithic, a period that lasted some 800 years 64 . Substantial architectural remains belonging to this culture were recovered for example, at the site of Tel Tsaf located in the Jordan Valley, where stone-built dwellings, a water well and round silos were recovered, as well as hundreds of charred olive pits 65 , and olive wood 23 . The data from Hishuley Carmel, Tel Tsaf and other Chalcolithic sites, including those to the east of the Jordan River 27 , 32 , then corroborate the augmented exploitation of olives at this time that is also illustrated in the regional pollen record as detailed above.…”

“…This was followed by a significant increase in the quantities of olive pits recovered from numerous archaeological deposits in the Southern Levant dating to 7,000 to 6,500 BP 25 – 31 . Thus, both archaeobotanical finds and pollen data suggest that the initial cultivation of olives first took place in the Southern Levant no later than ~ 6,500 BP 23 , 25 , 31 , 32 .…”

“…A significant increase in Olea sp. pollen grain percentages during the 7th millennium BP has led researchers to conclude that olive cultivation first occurred in the southern Levant by ~ 6,500 years BP, and later dispersed to other parts of the Mediterranean Basin 21 – 23 . Remains of olive wood and/or olive pollen have been reported from many Late Pleistocene-Early Holocene Southern Levantine sites, including the 9th millennium BP submerged site of Atlit Yam 24 .…”