Scientists Follow a Grain to the Origins of Agriculture
If there was anything like a first garden, it may well have been a prehistoric weed patch in a narrow swatch of Turkish hills where, new scientific evidence suggests, the first farmers turned wild plants into crops.
In research announced Thursday, scientists said they had used DNA fingerprinting to trace the origin of a “founder crop” called einkorn wheat to one corner of the ancient Fertile Crescent, which many experts consider the site of the single most important event in history--the invention of agriculture 10,000 years ago.
The new genetic analysis also suggests that it may have taken less than a hundred years to transform the wild wheat into a useful cereal crop, setting in motion surprisingly quickly the forces that would transform a primitive human society of hunters and gatherers into the centralized technological civilization that dominates so much of the world today.
The new research helps narrow the location of the origin of agriculture. “Out of the eight founder crops in the Fertile Crescent, this is the third to be nailed down . . . and all three to be nailed down are in southeastern Turkey,” said UCLA physiologist Jared Diamond, who studies the relationships between biology, evolution and society.
The research, published today in Science, was performed by scientists at the Agricultural University of Norway in As, Norway, and the Max Planck Institute in Cologne, Germany.
The researchers reported that the wheat was first cultivated near the Karacadag Mountains in southeastern Turkey, where chickpeas and bitter vetch also originated. Bread wheat--the most valuable single crop in the modern world--grapes and olives were domesticated nearby, as were sheep, pigs, goats and cattle.
Although agriculture developed independently in China and the New World, this collection of domesticated plants and animals gave western Eurasian societies an “enormous head start” over other cultures, experts said, triggering the emergence of stratified societies, literacy, metallurgy, advanced weapons and empires.
“It really gave Near Eastern populations a head start, big time,” said Bruce D. Smith, director of the archeobiology program at the Smithsonian’s National Museum of Natural History. “It is a remarkable congruence of plants and animals all domesticated in a relatively small geographic area very early--a remarkable jackpot.”
No one knows who first cultivated these plants. The researchers speculate that it may have been a single tribe, perhaps a single family, who first stumbled on the idea of agriculture.
“We believe that the idea is so good--the idea of cultivating wild plants--that we think it might be one tribe of people, and that is fascinating,” said Manfred Heun at the University of Norway’s department of biotechnological sciences, who led the research team. “I cannot prove it, but it is a possibility that one tribe or one family had the idea.”
Archeological evidence has long pointed to the hardy, yellow grain of einkorn wheat as one of the earliest known crops, along with barley, peas, lentils, chickpeas, broad bean, bitter vetch and flax. All appear to have been domesticated in this part of the world at about the same time: between 9,500 and 10,000 years ago, when the ice age was drawing to a close and humans subsisted by hunting and scavenging.
In their search for the precise origins of agriculture, the researchers selected einkorn wheat, in part because the hulled grain fell out of favor with farmers thousands of years ago at the end of the Bronze Age and, therefore, has remained largely untouched by modern plant breeders.
“When you look at today’s modern wheat, it has been crossed with just about everything and then it is difficult to trace it back to its wild source,” Heun said. “Here we had a species untouched by modern genetics and breeding, and the wild [where it originated] is still the wild, untouched.”
To retrace the plant’s genetic pedigree, Heun and his colleagues gathered 1,300 variants of einkorn wheat from 10 gene banks around the world. They narrowed their test group to 338 samples by picking only those whose geographic origin was known precisely. They analyzed them for 11 genetic traits.
It quickly became apparent that it took an alteration in just one or two genes to transform the ancient wild wheat into a useful crop, Heun said. And that was enough to start the first regular cultivation of plants.
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In contrast, so many drastic genetic changes were needed to transform the wild ancestor of maize in Mexico--teosinte--into a useful cereal that it may have taken 2,000 years, Diamond said. So many changes were necessary that some experts still dispute the idea that maize is descended from teosinte.
The key change in einkorn wheat apparently involved the brittleness of the stalk, which naturally snaps easily to scatter the seeds on the ground. Under cultivation, however, a variant of the plant speedily developed, holding onto its seed grains until harvested by human hands.
The first farmers may have had no intention of developing a crop nor any idea how radically agriculture would change their societies. The plant and the people tilling it naturally adapted to each other in a symbiotic relationship that underpins civilization today.
“As humans plant them and as they harvest them, the plants change,” Smith said. “The changes are ones that [naturally] are advantageous to humans. That means these changes can then take place fairly quickly. They don’t even need deliberate selection.
“Humans just need to start planting and harvesting them,” Smith said. “As soon as they do that, the plants respond.”
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First Farms
New scientific evidence suggests that the first crops originated along a narrow swatch of hills in southeastern Turkey, part of the ancient Fertile Crescent region.
