The domestication of agricultural
plants is thought to have begun in the Middle East around the onset of the
Holocene, about 11 700 years ago, with agriculture rapidly spreading across
Europe, Asia and northern Africa as the practice was either adopted by
hunter-gatherer communities or these communities were replaced by peoples who
had adopted the new technology. Evidence for such agriculture comes not just
from the presence of crops at archaeological sites, but also the presence of
agricultural weeds, plants which have evolved to invade cultivated fields but
which are not themselves cultivated. However caution needs to be used when
relying on this form of evidence, as they are derived from wild plants
specializing in the colonizing of disturbed ground, many of which have long
histories of close associations with Humans, due to our habit of modifying
environments by fire or other methods of clearing.
In a paper published in the
journal PLoS One on 22 July 2015, Ainit Snir of the Martin (Szusz) Department of Land of Israel Studies and Archaeology at Bar Ilan University, Dani Nadel
and Iris Groman-Yaroslavski of the Zinman Institute of Archaeology at Haifa University, Yoel Melamed of the Mina and Everard Goodman Faculty of Life Sciences at Bar-Ilan University, Marcelo Sternberg of the Department of Molecular Biology and Ecology of Plants at Tel Aviv University, Ofer Bar-Yosef
of the Department of Anthropology at Harvard University and Ehud Weiss also of
the Martin (Szusz) Department of Land of Israel Studies and Archaeology at Bar
Ilan University discuss the presence of seeds from agricultural crops and weeds
at the 23 000-year-old Ohalo II site on the southwest shore of the Sea of
Galilee in southern Israel.
The Ohalo II site was occupied
during the last Glacial Maximum by people interpreted as settled
hunter-gatherers. The site comprises six brush huts, and several hearths (fire
places) as well as a single grave, of an adult male. The site was inundated by
rising waters on the Sea of Galilee shortly after it was abandoned, and
remained covered by water until 1989, when it was exposed following several
years of heavy water extraction from the lake. The site was excavated between
1989 and 1991 and again between 1998 and 2001.
Location map of Ohalo II and central area of excavation at the site.
Snir et al. (2015).
Ohalo II has yielded a large
number of seeds and fruits (about 150 000 specimens) suggesting the people
enjoyed a diet including emmer wheat, barley, peas, lentils, almonds, figs,
grapes and olives, similar to that of later agricultural peoples in the Middle
East. The site is inferred to have been settled year-round from the presence of
remains of migratory Birds which would have been present at different times of
year and seeds and fruits from plants which would also have been produced at
different times. As well as a wide range of artefacts and food remains, the
site also shows evidence of invasion by pest species, including House Mice, Mus musculus, and Black Rats, Rattus rattus.
As well as a wide variety of food
seeds, a large number of seeds from weed species were also recovered (15 726
identified specimens, about 10.5% of the total sample). These comprised
thirteen different weed species, though the sample was dominated by Corn
Cleavers, Galium tricornutum, with
the presence of Darnel, Lolium temulentum,
also considered to be important. These two plants are particularly significant
as they are only known as agricultural weeds growing in cereal fields today,
with their original habitat unknown. Four other species present, Chenopodium album, Malva parviflora, Notobasis
syriaca and Silybum marianum, are
also considered agricultural weeds today, though these species are also
sometimes eaten, so caution needs to be used when implying their significance
at archaeological sites.
When working with Holocene cereal
samples archaeologists typically separate cultivated crops from wild plants by
the disarticulation scars on their rachises (expand), with smooth scars being
considered ‘wild-type’ and rough scars ‘domestic’; where more than 10% of the
sample has domestic rough scars it is thought that the sample is likely to be
of agricultural rather than wild origin. The Ohalo II samples of two cereals
exceed this limit, with Wild Barley, Hordeum
spontaneum, yielding 36% domestic-type scars and Wild Wheat, Triticum dicoccoides, yielding 25%
domestic-type scars.
Wild-type (left) and domestic-type (right) scars in rachises of Wild
Barley, Hordeum spontaneum, from
Ohalo II. Snir et al. (2015).
Snir et al. are cautious in their interpretation of these results,
noting that the ‘rough’ domestic scar is typically the result of harvesting
dry, yellow seeds rather than green or yellow-green seeds, rather than any
inherent difference in the plants. Domestic fields of cereals are planted at
the same time and mature at the same time, leading to farmers being able to
harvest more-or-less entirely yellow seeds. With wild-growing cereals plants at
different stages of maturity tend to be present, leading to a mixture of
yellow, yellow-green and green seeds being harvested, typically leading to a
‘wild-type’ sample, with a high proportion of smooth scars. However a number of
experiments on Wild Barley harvesting at different sites in Israel have shown
that a high level of smooth, domestic type, scars can be achieved if the plants
are allowed to dry between harvesting and winnowing, suggesting that the Ohalo
II sample could be a result of the practices used in food preparation rather
than evidence of agriculture.
Wild Barley, Hordeum spontaneum.
(A) Wild Barley field in Yakum Park (18 March 2013). It grows here with other species
such as Galium aparine, Chrysanthemum coronarium, Notobasis syriaca, and Anthemis sp. (B) Same field, showing
wild barley at three ripening stages – green, green-yellow and yellow. Snir et al. (2015).
The Ohalo II site has also
produced a number of flint sickle-blades with a distinctive glossed surface pattern.
This is considered typical of the Early Holocene Natufian culture, found in the
Middle East roughly 10 000 years later than the Ohalo II site is thought to
have been occupied. Experimental work on harvesting with flint tools has shown
that such a smooth surface can be produced by cutting green and yellow-green
cereal stems; this lends support to the idea that the Ohallo II inhabitants
were harvesting green and yellow-green cereals then allowing them to dry before
winnowing, and also suggests that the similarity between Ohalo II and Natufian
tools is a product of similar practices rather cultural continuity.
Sickle blade from Ohalo II. (A) Macrograph of the sickle blade. (B)
Micrograph showing the use-wear polish produced by cereal harvesting, observed
along the sharp edge of the blade (original magnification ´
200). (C) Micrograph showing hafting wear including streaks of polish
associated with rounding observed along the opposite edge (original
magnification ´ 100). Snir et al. (2015).
Snir et al. do not suggest that agriculture began at, or close to, Ohalo
II 10 000 years earlier than previously realized and subsequently spread across
the Middle East, but rather that some experimentation with plants that later
became agricultural crops was occurring at this time. They note that this is
common in palaeoarchaeological studies, with evidence suggesting that many
technologies show a long period of experimentation before they are perfected
and become widespread. There is no evidence to suggest that the practices
present at Ohalo II led directly to later development of agriculture across the
Middle East, but they do indicate that the population, reacted to similar
environmental conditions as the later proto-agriculturalists in a similar way,
by experimenting with the control and harvesting of cereal crops that became
possible once the population was permanently settled in an area where these
plants naturally occurred.
See also…
Early modern Humans expanded from Africa around the globe in the Late Pleistocene, from about 125 000 years ago onwards. In doing so they adapted to a wide variety of environments, though some habitats are thought...
Stone tools associated with the Acheulian technology first appeared around 1.75 million years ago and spread across much of Eurasia from about 900 000 years ago onwards. The technology is typified by tools in which pieces are chipped away from a central core to leave...
The Nefud Desert lies in the northwest of Saudi Arabia, and is thought to have been one of the key obstacles that early Humans, and other Hominids, had to pass as they expanded out of Africa into Southwest Asia...
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