Olives are the fruit of a tree that today can be found as nearly 2,000 separate cultivars within the Mediterranean basin alone. Today olives come in a huge variety of fruit sizes, shape, and color, and they are grown on every continent except Antarctica. And that may in part be why the history and domestication story of olives is a complicated one.
Olives in their native state are virtually inedible by humans, although domestic animals like cattle and goats don't seem to mind the bitter flavor. Once cured in brine, of course, olives are very tasty. Olive wood burns even when wet; which makes it very useful and that may be one attractive characteristic that drew people towards the management of olive trees. One later use was for olive oil, which is virtually smoke-free and can be used in cooking and lamps, and in many other ways.
The olive tree (Olea europaea var. europaea) is thought to have been domesticated from the wild oleaster (Olea europaea var. sylvestris), at a minimum of nine different times. The earliest probably dates to the Neolithic migration into the Mediterranean basin, ~6000 years ago.
Propagating olive trees is a vegetative process; that is to say, successful trees are not grown from seeds, but rather from cut roots or branches buried in the soil and allowed to root, or grafted onto other trees. Regular pruning helps the grower keep access to the olives in the lower branches, and olive trees are known to survive for centuries, some reportedly for as much as 2,000 years or more.
The first domesticated olives are likely from the Near East (Israel, Palestine, Jordan), or at least the eastern end of the Mediterranean Sea, although some debate persists about its origins and spread. Archaeological evidence suggests that the domestication of olive trees spread into the western Mediterranean and North Africa by the Early Bronze Age, ~4500 years ago.
Olives, or more specifically olive oil, has a significant meaning to several Mediterranean religions: see the History of Olive Oil for a discussion of that.
Olive wood samples have been recovered from the Upper Paleolithic site of Boker in Israel. The earliest evidence of olive use discovered to date is at Ohalo II, where ca 19,000 years ago, olive pits and wood fragments were found. Wild olives (oleasters) were used for oils throughout the Mediterranean basin during the Neolithic period (ca 10,000-7,000 years ago). Olive pits have been recovered from the Natufian period (ca 9000 BC) occupations in Mount Carmel in Israel. Palynological (pollen) studies on the contents of jars have identified the use of olive oil presses by the early Bronze Age (ca 4500 years ago) in Greece and other parts of the Mediterranean.
Scholars using molecular and archaeological evidence (presence of pits, pressing equipment, oil lamps, pottery containers for oil, olive timber, and pollen, etc.) have identified separate domestication centers in Turkey, Palestine, Greece, Cyprus, Tunisia, Algeria, Morocco, Corsica, Spain, and France. DNA analysis reported in Diez et al. (2015) suggests that the history is complicated by admixture, connecting domesticated versions with wild versions throughout the region.
Important Archaeological Sites Sites
Archaeological sites important to understanding the domestication history of the olive include Ohalo II, Kfar Samir, (pits dated to 5530-4750 BC); Nahal Megadim (pits 5230-4850 cal BC) and Qumran (pits 540-670 cal AD), all in Israel; Chalcolithic Teleilat Ghassul (4000-3300 BC), Jordan; Cueva del Toro (Spain).
Sources and Further Information
Plant Domestication and the Dictionary of Archaeology.
Breton C, Pinatel C, Médail F, Bonhomme F, and Bervillé A. 2008. Comparison between classical and Bayesian methods to investigate the history of olive cultivars using SSR-polymorphisms. Plant Science 175(4):524-532.
Breton C, Terral J-F, Pinatel C, Médail F, Bonhomme F, and Bervillé A. 2009. The origins of the domestication of the olive tree. Comptes Rendus Biologies 332(12):1059-1064.
Diez CM, Trujillo I, Martinez-Urdiroz N, Barranco D, Rallo L, Marfil P, and Gaut BS. 2015. Olive domestication and diversification in the Mediterranean Basin. New Phytologist 206(1):436-447.
Elbaum R, Melamed-Bessudo C, Boaretto E, Galili E, Lev-Yadun S, Levy AA, and Weiner S. 2006. Ancient olive DNA in pits: preservation, amplification and sequence analysis. Journal of Archaeological Science 33(1):77-88.
Margaritis E. 2013. Distinguishing exploitation, domestication, cultivation, and production: the olive in the third millennium Aegean. Antiquity 87(337):746-757.
Marinova, Elena. "An experimental approach for tracing olive processing residues in the archaeobotanical record, with preliminary examples from Tell Tweini, Syria." Vegetation History and Archaeobotany, Jan M. A. van der Valk, Soultana Maria Valamoti, et al., 20(5), ResearchGate, September 2011.
Terral JF, Alonso N, Capdevila RBi, Chatti N, Fabre L, Fiorentino G, Marinval P, Jordá GP, Pradat B, Rovira N, et al. 2004. Historical biogeography of olive domestication ( Journal of Biogeography 31(1):63-77.Olea europaea L.) as revealed by geometrical morphometry applied to biological and archaeological material.