by Emma J Devereux
Citation: Devereux, E.J., (2021) How Agriculture Began: 12,000 Years of Crop Cultivation EcoFoodDev, https://www.ecofooddev.com/crop-cultivations-astonishing-age-1000s-of-years-of-change/
What do we mean by “cultivation”?
Previously we looked at what is meant by domestication of cereals, and now we will consider the evidence for cereal cultivation, and when and where modern crops emerged.
Cultivation involves clearing and preparing land for sowing of selected seeds. In times past, as well as today, this usually requires the burning of woodland to create space and remove competition.
First, let’s consider times past and the beginnings of cereal cultivation. Fascinating and convincing evidence for cultivation of cereals before their domestication comes from an archaeological site named Jerf el Ahmar in northern Syria (the site is unfortunately now submerged beneath Tishrin Dam).
People lived at this site from roughly 9200 to 8700 BC. Occupants were processing barley here nearly 1000 years before its domestication (its changing to a domesticated form). Archaeologists at Jerf El Ahmar unearthed over 400 querns, with roughly 30 in situ (still in place). A quern is a type of mill, comprised of two circular stones, that was used to grind seeds into corn.
The quern stones showed signs of prolonged wear. This suggests a society involved in large scale processing of cultivated crops. Archaeologists also discovered technology for cereal processing in dedicated rooms, including harvesting tools such as sickles, and constructed storage structures. This indicates a trend toward growing reliance on cereal exploitation and increased social complexity.
Centres of Origin
Genetic studies are used to identify the ancestors of modern cereal crops and their path towards domestication. Centres of origin are important, as they describe the main centre of diversity that is characteristic to that crop, and understanding this can have huge implications for crop modification, crop management, and agricultural sustainability. It is my belief that a clear understanding of the archaeobotanical pathway towards domestication can provide insights for agri-innovation in crop science in the face of climate change, particularly with regards to crop wild relative research which I will discuss in future posts. It is one of the many ways, I believe, that we can use information from the past to solve problems today.
For example, molecular fingerprinting was used to calculate genetic distances between species of barley. These distances between cultivated crops and wild type crops increase from the southern to the northern Fertile Crescent (modern Turkey, Iran etc. as discussed in the previous post). The samples analysed in southern Iran are closer to cultivated barley than those from regions further north. Barley examined from the Himalayas and the Mediterranean is closely related to H. vulgare (the modern barley that we are familiar with located in what we might term the western Fertile Crescent of countries such as Israel), while wild barley from central Asia is closer to H. spontaneum (wild barley) from the eastern Fertile Crescent ( countries such as Iran).
What does all this mean? These results indicate that barley of the Iranian type, and barley of the Isreali type, are in fact two different wild species. The results also show that barley classified as the Mediterranean type is related to the Isreali lines. The Himalayan barley samples are genetically related to the Iranian group. Understanding the conditions under which these species evolved provides greater understanding of the nature of the plant and associated taxa (it’s wild relatives), and possible modifications in the face of changing environmental conditions.
This evidence has been interpreted as suggesting that the southern part of the Fertile Crescent is the area where wild barley was domesticated. Experiments also indicate that European and American cultivars are derived from wild barley from the Fertile Crescent, but that wild barley from Central Asia contributed to barley cultivated from Central Asia to the Far East (in essence, going the other direction). Wild barleys found in Tibet were analysed and compared with samples from the Near East. The results showed that the split between Near Eastern wild barleys and those in Tibet happened over 2.5 million years ago. It may be the case that wild barley from the Near East migrated to central Asia, and then moved into the harsh Tibetan climate, where it underwent changes in order to adapt to the climate.
Single Vs. Multiple Origins
As mentioned above, there is debate as to whether cereals originated and spread from one, core area, or whether there are multiple sites. Researchers and archaeobotanists suggest that there were multiple centres of origin for cereal domestication, with false starts and disease affecting origin and spread in some places. It is proposed that crops were domesticated slowly in a number of centres throughout the Near East, and that, as mentioned, pre-domestication cultivation was occurring at a number of sites throughout the Near East prior to the emergence of domesticated cereals. Grains domesticated in one part of the Levant may not have thrived in other areas, where a more durable or hardy strain may have been needed. Other researchers argue the contrary, claiming that as founder crops are self-pollinating, they will naturally be isolated genetically from their wild progenitors and be rapidly domesticated. There appear to be many proponents on each side of the argument, and the debate is ongoing. In the next post I will briefly outline how the domestication of cereal crops led to the emergence of modern society as we know it.
References
Badr, A. and El-Shazly, H., 2012. Molecular approaches to origin, ancestry and domestication history of crop plants: Barley and clover as examples. Journal of Genetic Engineering and Biotechnology, 10(1), pp.1-12.
Fuller, D.Q., Willcox, G. and Allaby, R.G., 2012. Early agricultural pathways: moving outside the ‘core area’hypothesis in Southwest Asia. Journal of experimental botany, 63(2), pp.617-633.
Morrell, P.L. and Clegg, M.T., 2007. Genetic evidence for a second domestication of barley (Hordeum vulgare) east of the Fertile Crescent. Proceedings of the national academy of sciences, 104(9), pp.3289-3294.
Vavilov, N.I., 1926. Studies on the origin of cultivated plants.
Willcox, G. and Stordeur, D., 2012. Large-scale cereal processing before domestication during the tenth millennium cal BC in northern Syria. Antiquity, 86(331), pp.99-114.
Cover image: Wikicommons
