The spread of food production
from the Fertile Crescent. The purple-shaded area is the crescent itself,
where food production was established by 8000 B.C. Lines denote how far
food production, on the basis mostly of Fertile Crescent crops and livestock,
had spread by the indicated dates (calibrated radiocarbon B.C. dates).
Based on maps 2 and 20 of (3), as modified in (4).
Botanists already knew that cultivated einkorn's ancestor was a very similar wild cereal that still grows in natural habitats in the crescent (3). It was unknown, however, where within the crescent wild einkorn was first taken into cultivation. Heun et al. (1) analyzed DNA from 68 lines of cultivated einkorn, plus 261 wild einkorn lines sampled over the crescent's whole expanse as well as outside the crescent.
Among those wild lines, the most distinct genetically proved to be a group of 11 from the Karacada mountains of southeast Turkey. [HN7], [HN8], [HN9], [HN10], [HN11] Those 11 also turned out to be the ones genetically most similar to cultivated einkorn, and so presumably the crop's immediate ancestors. This discovery is compatible with previous nonmolecular evidence. The Karacada mountains were already known to support stands of wild einkorn so dense and extensive that they were being harvested by hunter-gatherers even before einkorn's domestication. Nearby archaeological sites contain remains of both wild and cultivated einkorn and are among the crescent's oldest farming sites.
What are some of the broad implications of these findings? Genetically and morphologically, cultivated einkorn is quite similar to wild einkorn in general. Now that the specific wild ancestral line has been identified as being even more similar to the crop, we can better appreciate why einkorn's domestication was so easy and quick. The crescent's archaeological record shows that at most a few centuries were required for the transition from hunter-gatherer villages harvesting wild plants to farming villages planting fully domesticated crops. For einkorn (and probably for the other founder crops as well), that transition required changes in only a few genetic loci, which account for the few morphological changes distinguishing the crop from wild einkorn (1).
But those few changes were of great value to the earliest farmers. They included heavier seeds and denser seed masses (yielding a crop even more productive than its wild ancestor), plus a firm stalk making seeds more easily harvestable by preventing them from dropping to the ground. Repeated cycles of sowing, growing, and harvesting wild einkorn would have selected automatically for those mutations (3). The first cultivators could have had no conscious intent to produce a crop, and no way of anticipating how radically agriculture would change their societies.
These few, simple changes during einkorn's domestication contrast sharply with the drastic biological reorganization required for the domestication of Native Americans' leading cereal, maize, from its wild ancestor, teosinte. [HN12], [HN13] This difference alone helps explain why densely populated agricultural societies arose so much earlier and developed so much more rapidly in the crescent than in the New World.
Can we attach any significance to the new finding that, within the crescent, einkorn was domesticated specifically in southeast Turkey rather than at some other site? Here we find another clue to the early rapid rise of crescent agriculture. In different parts of the crescent lived wild species ancestral to some of the world's earliest and most useful species of crops and livestock. With the discovery by Heun et al. (1), we can pinpoint the origins of three of the crescent's eight founder crops (chickpea,[HN14] bitter vetch, and now einkorn) to eastern Turkey. Grapes and olives were domesticated nearby to the south; sheep, pigs, goats, and cattle close by in possibly the central, north central, eastern, and western crescent, respectively; and barley,[HN15] emmer wheat,[HN16] peas, lentils, and flax in still-to-be-identified parts of the crescent. Only slightly to the northeast of the crescent, on the shores of the Caspian Sea, grows the wild grass Aegilops squarrosa. When it hybridized with cultivated emmer wheat spreading east from the crescent, the result was bread wheat, the most valuable single crop in the modern world. Thus, the crescent's diversity of useful wild plant and animal species, living in close proximity to each other, enabled the crescent's first farmers quickly to assemble a balanced package of domesticates meeting all of humanity's basic needs: carbohydrates, protein, oil, milk, animal transport and traction, and vegetable and animal fiber for rope and clothing (3, 4).
That valuable package spread rapidly through and beyond the crescent (see the figure), not only outcompeting hunter-gatherer economies in productivity, but also preempting alternative sequences of plant and animal domestication that might otherwise have arisen elsewhere in western Eurasia. The spread was accelerated by the west-east axis of the whole Eurasian continent as well as of the crescent itself, permitting crops, livestock, and people to expand at the same latitude without having to adapt to new day lengths, climates, and diseases. Cultivated einkorn's rapid diffusion from the Karacada mountains preempted possible independent domestications of einkorn elsewhere in its wild range. The rapid diffusion of both einkorn and emmer in turn preempted widespread cultivation of other related domesticable wild grasses, such as Timopheev's wheat. In contrast, the New World's north-south axis required domesticates to adapt to changes of latitude as they spread. The resulting slow spread of crops within Native America permitted numerous independent domestications of the same crop or of related crops (for example, squashes and cottons) in different areas. Within less than 2000 years of the beginnings of domestication in the crescent, its results had been carried east and west to launch the origins of food production over a huge swath of Eurasia (see the figure), from Pakistan to the Balkans (3). Food production's expansion over the Americas, Africa, and the Indian subcontinent was much slower because of the north-south axes of those landmasses (4). In short, einkorn domestication in the Karacada mountains exemplifies the enormous head start that western Eurasian societies gained from Fertile Crescent biogeography. For history's broad patterns, as for real estate investment, location is almost everything. Plant and animal domestication was prerequisite to the growth of large, dense, sedentary human populations, in which the food-producing activities of part of the population yielded storable food surpluses to feed non-food-producing parts of the population. Hence, food production triggered the emergence of kings, bureaucrats, scribes, professional soldiers, and metal-workers and other full-time craftspeople (4). Literacy, metallurgy, stratified societies, advanced weapons, and empires rested on food production. In addition, smallpox and the other crowd epidemic diseases of Eurasia could evolve only in those dense, sedentary human populations living in close contact with domesticated animals, whose own pathogens evolved into those specialized pathogens afflicting us (4). Thus, a long straight line runs through world history, from those first domesticates at the Karacada mountains and elsewhere in the Fertile Crescent, to the "guns, germs, and steel" by which European colonists in modern times destroyed so many native societies of other continents.
1.M. Heun et al., Science 278, 1312 (1997).
2.All dates that I cite are so-called calibrated radiocarbon dates,[HN17] which are corrected for temporal fluctuations in atmospheric carbon isotope ratios and thus correspond to approximate calendar years. The dates in (1) are younger because they instead are uncalibrated dates.
3.D. Zohary and M. Hopf, Domestication of Plants in the Old World (Oxford Univ. Press, Oxford, ed. 2, 1993).
4.J. Diamond, Guns, Germs, and Steel: The Fates of Human Societies (Norton, New York, 1997).[HN18]
The author is in the Department
of Physiology, UCLA School of Medicine, Los Angeles, CA 90095, USA. E-mail:
jdiamond@physiology.medsch.ucla.edu
HyperNotes
Related Resources on the World Wide Web
General Hypernotes
GrainGenes is a compilation of molecular and phenotypic information on wheat, barley, oats, rye, and sugarcane. The project is supported by the USDA/NAL Plant Genome Research Program. Kinds of information offered by GrainGenes include: genetic and cytogenetic maps; genomic probes and nucleotide sequences; genes, alleles, and gene products and associated phenotypes; pathologies and pathogens; a taxonomy of the Triticeae and Avena; and relevant bibliographic citations.
Plants, Genes and Global Food Production provides information to accompany a course offered by the Cornell University Department of Plant Breeding. The Index of Course Readings provides links to the full text of selected readings on food crops and their domestication. Readings for Lecture 2, Evolution and Domestication of Food Crops, present discussions of plants, genes, and the emergence of agriculture.
The South-West Asia Synthesis Report is one of a series of country and sub-regional reports on plant and genetic resources developed by the Food and Agriculture Organization of the United Nations. This report provides information on plant species of agricultural importance in the region and their wild relatives, the history of agriculture in the region, plant genetic resources conservation activities, and socioeconomic conditions of the nations and territories in southwest Asia. The Country Report for the Republic of Turkey provides additional information on einkorn wheat and its wild relatives in western Asia. Indigenous Plant Genetic Resources, a chapter of the Country Report for Ethiopia, suggests that Ethiopia may be the center of origin of the chickpea and the lentil.
Through its Web site, the National Agricultural Library provides a list of Internet resources for agriculture. The World Wide Web Virtual Library: Agriculture is an extensive list of Internet resources for agriculture. This page is maintained by the National Science Foundation Center for Integrated Pest Management, located at North Carolina State University.
Numbered Hypernotes
1.Jared Diamond's Web page describes his research interests and lists representative publications. Why Did Human History Unfold Differently on Different Continents for the Last 13,000 Years? is a faculty research lecture by Jared Diamond on a topic related to this Perspective.
2.The Indo-European Language Tree by Dan Short is available through the Old English Pages maintained at Georgetown University.
3.Exploration of Language is a brief tutorial on linguistics and language families, including the Indo-European language family.
4.Einkorn, emmer, and other varieties of wheat are described in Alternative Wheat Cereals as Food Grains: Einkorn, Emmer, Spelt, Kamut, and Triticale by G. F. Stallknecht, K. M. Gilbertson, and J. E. Ranney. This page is one of several pages in NewCROP, the Web site of the Center for New Crops and Plant Products at Purdue University.
5.Lost Crops of Africa: Volume I: Grains (Washington, DC, National Academy Press, 1996) presents a discussion of einkorn and emmer wheat.
6.PLB143: Evolution of Crop Plants is an outline of a course offered at the University of California, Davis. Detailed lecture outlines provide lists of readings in addition to facts about the domestication of plants with illustrations and tables. Lecture 08: What is a crop? The domestication syndrome outlines the changes that occurred in einkorn and emmer wheat in the process of domestication.
7.A remote sensing image of the Karacada region of Turkey is available from the German Remote Sensing Data Center (Deutsches Fernerkundungsdatenzentrum).
8.Geographical Regions of Turkey, available through the Republic of Turkey Web site, describes Karacada as one of the main peaks in the Central Anatolian region of Turkey.
9.Maps of Turkey and the Middle East are available from the Perry-Castaneda Library Map Collection at the University of Texas.
10.The Classics and Mediterranean Archaeology Server is a list of resources on the World Wide Web for the archaeology of the Mediterranean region.
11.Tourist maps of Turkey are available from FOCUS Multimedia.
12.Green Genes by Gerald R. Fink describes teosinte and the domestication of maize. Green Genes is a chapter of Access Excellence, a national educational program on the World Wide Web that provides high school biology teachers access to sources of new scientific information about biotechnology.
13.Poaceae includes a description and photograph of teosinte (Zea diploperennis).
14.The NewCROP Fact Sheet for chickpea presents information on the origin of chickpea.
15.Hordeum vulgare describes common barley and includes an illustration from the National Small Grains Collection.
16.Triticum dicoccon provides a brief description and an illustration of emmer wheat from the National Small Grains Collection.
17.Radiocarbon WEB-info describes radiocarbon dating and calibration of radiocarbon dates. A list of other Web sites related to radiocarbon dating is included.
18.Guns, Germs and Steel by Jared Diamond is available from W. W. Norton & Company.
19.Department of Physiology, UCLA School of Medicine.
Volume 278, Number 5341
Issue of 14 November 1997, pp. 1243 - 1244
©1997 by The American
Association for the Advancement of Science.
Related Item
Site of Einkorn Wheat Domestication
Identified by DNA Fingerprinting
Science 14 November 1997; 278
(5341):1312 (in Reports)
M. Heun, R. Schäfer-Pregl,
D. Klawan, R. Castagna, M.
Accerbi, B. Borghi, F. Salamini
Copyright © 1997 by the American Association for the Advancement of Science.
New York Times (November 18, 1997)
The greatest thing before sliced bread, to reverse the cliche, was bread itself. The first cultivation of wild grains, that is, turned hunter-gatherers into farmers, beginning some 12,000 to 10,000 years ago. In the transition, people gained a more abundant and dependable source of food, including their daily bread, and changed the world forever.
Archaeologists and historians agree that the rise of agriculture, along
with the domestication of animals for food and labor, produced the
most important transformation in human culture since the last ice age
-- perhaps since the control of fire.
Farming and herding led to the growth of large, settled human populations and increasing competition for productive lands, touching off organized warfare. Food surpluses freed people to specialize in crafts like textiles and supported a privileged elite in the first cities, growing numbers of bureaucrats and scribes, soldiers and kings.
Excavations at more than 50 sites over the last half-century have established the Fertile Crescent of the Middle East as the homeland of the first farmers.
This arc of land, broadly defined, extends from Israel through Lebanon and Syria, then through the plains and hills of Iraq and southern Turkey and all the way to the head of the Persian Gulf. Among its "founder crops" were wheat, barley, various legumes, grapes, melons, dates, pistachios and almonds. The region also produced the first domesticated sheep, goats, pigs and cattle.
But questions persist: Where in the Fertile Crescent were the first wheat and barley crops produced? What conditions favored this region? Why was the transition from hunting and foraging to farming so swift, occurring in only a few centuries?
New genetic studies suggest possible answers. They pinpoint the Karacadag Mountains, in southeast Turkey at the upper fringes of the Fertile Crescent, as the site where einkorn wheat was first domesticated from a wild species around 11,000 years ago.
Moreover, they reveal that cultivated einkorn plants, as botanists had suspected, are remarkably similar genetically and in appearance to their ancestral wild varieties, which seems to explain the relatively rapid transition to farming indicated by archaeological evidence.
A team of European scientists, led by Dr. Manfred Heun of the Agricultural University of Norway in As, reported these findings in the current issue of the journal Science. The researchers analyzed the DNA from 68 lines of cultivated einkorn wheat, Triticum monococcum monococcum, and from 261 wild einkorn lines, T.m. boeoticum, still growing in the Middle East and elsewhere.
In the study, the scientists identified a genetically distinct group of 11 varieties that was also most similar to cultivated einkorn. Because that wild group grows today near the Karacadag Mountains, in the vicinity of the modern city of Diyarbakir, and presumably was there in antiquity, the scientists concluded, this is "very probably the site of einkorn domestication."
Knowing the site for the domestication of such a primary crop, the scientists said, did not necessarily imply that the people living there at the time were the first farmers. "Nevertheless," they wrote, "it has been hypothesized that one single human group may have domesticated all primary crops of the region."
Archaeologists said that radiocarbon dating was not yet precise enough to establish whether einkorn or emmer wheat or barley was the first cereal to be domesticated. All three domestications occurred in the Fertile Crescent, probably within decades or a few centuries of each other. It was a hybrid of emmer and another species from the Caspian Sea area that produced the first bread wheat. Dr. Bruce D. Smith, an archaeobiologist at the Smithsonian Institution and author of "The Emergence of Agriculture," published two years ago by the Scientific American Library, praised the research as another notable example of new technologies' being applied in trying to solve some of archaeology's most challenging problems. The einkorn findings, he said, made sense because they "fit pretty well with archaeological evidence."
Not far from the volcanic Karacadag Mountains and also to the south, across the border in northern Syria, archaeologists have exposed the ruins of prefarming settlements and early agricultural villages that appear to have existed only a few centuries apart in time. Sifting the soil turned up seeds of both wild and cultivated einkorn wheat. The ruins of Abu Hureyra, an especially revealing Syrian site on the upper Euphrates River, contained firm evidence of einkorn farming more than 10,000 years ago.
The European research team also pointed to this archaeological evidence as supporting its conclusion that the domestication of einkorn wheat began in the Karacadag area.
But some archaeologists may not readily accept the new findings. They have their own favorite areas where they think the first steps in plant domestication took place, and these happen to be to the west and south of the Turkish mountains.
Mud-brick ruins at the edge of an oasis in the Jordan River valley near Jericho have often been cited as from the world's first known farming village, occupied by an ancient people that archaeologists call the Natufians.
Dr. Frank Hole, a Yale University archaeologist who specializes in early agriculture, thinks the major center for early plant domestication was more likely in the corridor running north from the Dead Sea to Damascus.
Its Mediterranean-type climate, dry summers and mild but wet winters, which prevailed at the time of agricultural origins, would have favored the growth of annual plants like barley and both einkorn and emmer wheat. The Jericho site produced early evidence of barley cultivation.
Commenting on the new research, Hole said in an interview that "the location of domestication can't be determined by the present distribution of the wild plants." For example, einkorn does not grow wild today around Abu Hureyra, though excavations show that it must have more than 10,000 years ago. So it cannot be assumed, he said, that wild einkorn was growing in southeast Turkey at the time of domestication.
But Dr. Jared Diamond, a specialist in biogeography at the University of California at Los Angeles, disagreed, noting that the Karacadag Mountains supported "stands of wild einkorn so dense and extensive that they were being harvested by hunter-gatherers even before einkorn's domestication."
An experiment more than 25 years ago by Dr. Jack Harlan, an agronomist at the University of Illinois, demonstrated the likely importance of wild einkorn in the diets of post-ice age hunter-gatherers in the region and what might have encouraged them to domesticate it. Harvesting wild einkorn by hand in southeastern Turkey, Harlan showed that in only three weeks, a small family group could have gathered enough grain to sustain them for a full year.
In reaping the wild grain over a few decades, or at most three centuries, the hunter-gatherers unwittingly caused small but consequential changes in the plants. The new DNA analysis showed that an alteration of only a couple of genes could have transformed the wild einkorn into a cultivated crop.
In the wild, brittle stems hold the einkorn grains to the plant, making it easier for them to scatter naturally and reseed the fields. But natural mutations would have produced some semi-tough stalks that held the seeds more firmly in place.
People cutting the plants with sharp stone sickles would have selected the stalks more laden with grain, and these would be stored as next year's seed stock. Birds would be more apt to consume the dispersed grain from brittle stalks, leaving less of it to germinate.
As Diamond pointed out, repeated cycles of harvesting and reseeding wild einkorn stands "would have selected automatically for those mutations." Those changes included plumper, more nutritious grains in denser clusters that cling to the stem until ripe, instead of scattering before they can be harvested.
"These few, simple changes during einkorn's domestication," Diamond wrote in a separate article in Science, "contrast sharply with the drastic biological reorganization required for the domestication of Native Americans' leading cereal, maize, from its wild ancestor."
This difference alone, he said, "helps explain why densely populated agricultural societies arose so much earlier and developed so much more rapidly in the Crescent than in the New World."
It was several thousand more years before maize, or corn, would become a cultivated crop in central Mexico. There were no native wild wheats and barley in the Americas that might have led to an earlier introduction of agriculture there.
Such circumstances based on geographic location have often been critical in the timing and pace of cultural and economic development for diverse societies, as Diamond argued in "Guns, Germs, and Steel: The Fates of Human Societies," published earlier this year by W.W. Norton.
Nothing in the new einkorn research seems to alter current thinking about the timing and climatic circumstances for agriculture's genesis in the Fertile Crescent.
With the end of the ice age 14,000 to 12,000 years ago, retreating glaciers left the world warmer and wetter than before. Greater rainfall in many temperate zones nourished a spread of vegetation, including many grasses like wild wheat and barley.
This attracted concentrations of grazing animals. Hunter-gatherers converged on the grasses and animals, in many cases abandoning their nomadic ways and settling down to village life. Such conditions were particularly favorable in the Middle East.
Then followed a brief return of colder, drier weather more than 11,000 years ago and lasting a few centuries. Dr. Ofer Bar-Yosef, an archaeologist at Harvard University, thinks the stresses of coping with the Younger Dryas, as the dry spell is called, contributed to the beginning of plant domestication.
With the sudden dearth of wild food sources, hunter-gatherers began storing grain for the lean times and learning to cultivate the fields for better yields. In any case, the earliest evidence for agriculture so far comes from the period immediately after the Younger Dryas.
In his book on early agriculture, Smith of the Smithsonian wrote, "Even in the absence of such an external pressure, gradual growth in their populations and expansion of their villages may have encouraged or necessitated a variety of economic changes, including experimenting with the cultivation of wild grasses."
Whatever the factors behind its origins, Diamond said, agriculture took a firm hold in the ancient Middle East because of the diversity of plants and animals suitable for domestication. The first farmers, he said in the journal article, quickly assembled "a balanced package of domesticates meeting all of humanity's basic needs: carbohydrate, protein, oil, milk, animal transport and traction, and vegetable and animal fiber for rope and clothing."
Eurasian geography probably favored the rapid spread of agriculture out of the Middle East and throughout much of the two continents. Referring to a thesis developed in his book, Diamond pointed out that the west-east axis of the Eurasian land mass, as well as of the Fertile Crescent, permitted crops, livestock and people "to expand at the same latitude without having to adapt to new day lengths, climates and diseases."
In contrast, the north-south orientations of the Americas, Africa and
the Indian subcontinent probably slowed the diffusion of agricultural innovations.
And that, Diamond contends, could account for the head start some societies
had on others in the march of human history.