How the First Farmers Changed History

Carl Zimmer

Source - http://www.nytimes.com/2016/10/18/science/ancient-farmers-archaeology-dna.html?_r=0

A fossilized skeleton of a human who was buried beneath a floor in a family home in Ain Ghazal, a 10,000-year-old farming village in Jordan.  Credit C. Blair/The Ain Ghazal Archaeological Project

Beneath a rocky slope in central Jordan lie the remains of a 10,000-year-old village called Ain Ghazal, whose inhabitants lived in stone houses with timber roof beams, the walls and floors gleaming with white plaster.

Hundreds of people living there worshiped in circular shrines and made haunting, wide-eyed sculptures that stood three feet high. They buried their cherished dead under the floors of their houses, decapitating the bodies in order to decorate the skulls.

But as fascinating as this culture was, something else about Ain Ghazal intrigues archaeologists more: It was one of the first farming villages to have emerged after the dawn of agriculture.

Around the settlement, Ain Ghazal farmers raised barley, wheat, chickpeas and lentils. Other villagers would leave for months at a time to herd sheep and goats in the surrounding hills.

Sites like Ain Ghazal provide a glimpse of one of the most important transitions in human history: the moment that people domesticated plants and animals, settled down, and began to produce the kind of society in which most of us live today.

But for all that sites like Ain Ghazal have taught archaeologists, they are still grappling with enormous questions. Who exactly were the first farmers? How did agriculture, a cornerstone of civilization itself, spread to other parts of the world?

The influence of ancient farming villages in the Near East can still be seen in places like India. Credit Sanjay Kanojia/Agence France-Presse — Getty Images

Some answers are now emerging from a surprising source: DNA extracted from skeletons at Ain Ghazal and other early settlements in the Near East. These findings have already challenged long-held ideas about how agriculture and domestication arose.

What’s more, the new data are showing that early farmers would leave a tremendous mark. People from Ireland to India trace some of their ancestry to people who began growing barley and wheat in the Near East thousands of years ago.

“It’s a part of the story of civilization that we’re just beginning to understand,” said Iosif Lazaridis, a postdoctoral researcher at Harvard Medical School.

Altering False Impressions

The agricultural revolution changed our species and our planet. As bands of hunter-gatherers began domesticating plants and animals, they quit the nomadic life, building villages and towns that endured for thousands of years.

A stable food supply enabled their populations to explode, and small egalitarian groups turned into kingdoms sprawling across hundreds of miles.

Agriculture originated in a few small hubs around the world, but probably first in the Fertile Crescent, a region of the Near East including parts of modern-day Iraq, Syria, Lebanon, Israel and Jordan. The evidence for full-blown agriculture there — crops, livestock, tools for food preparation, and villages — dates back about 11,000 years.

In the Zagros Mountains of Iran, wild goats were domesticated over many centuries. Credit Fereidoun Biglari/National Museum of Iran

In the 1990s, archaeologists largely concluded that farming in the Fertile Crescent began in Jordan and Israel, a region known as the southern Levant. “The model was that everything started there, and then everything spread out from there, including maybe the people,” said Melinda A. Zeder, a senior research scientist at the Smithsonian National Museum of Natural History.

But in recent years, Dr. Zeder and other archaeologists have overturned that consensus. Their research suggests that people were inventing farming at several sites in the Fertile Crescent at roughly the same time. In the Zagros Mountains of Iran, for example, Dr. Zeder and her colleagues have found evidence of the gradual domestication of wild goats over many centuries around 10,000 years ago.

People may have been cultivating plants earlier than believed, too.

In the 1980s, Dani Nadel, then at Hebrew University, and his colleagues excavated a 23,000-year-old site on the shores of the Sea of Galilee known as Ohalo II. It consisted of half a dozen brush huts. Last year, Dr. Nadel co-authored a study showing that one of the huts contained 150,000 charred seeds and fruits, including many types, such as almonds, grapes and olives, that would later become crops. . A stone blade found at Ohalo II seemed to have been used as a sickle to harvest cereals. A stone slab was used to grind the seeds. It seems clear the inhabitants were cultivating wild plants long before farming was thought to have begun.

“We got fixated on the very few things we just happened to see preserved in the archaeological record, and we got this false impression that this was an abrupt change,” Dr. Zeder said. “Now we really understand there was this long period where they’re playing around with resources.”

Many scientists have suggested that humans turned to agriculture under duress. Perhaps the climate of the Near East grew harsh, or perhaps the hunter-gatherer population outstripped the supply of wild foods.

But “playing around with resources” is not the sort of thing people do in times of desperation. Instead, Dr. Zeder argues, agriculture came about as climatic changes shifted the ranges of some wild species of plants and animals into the Near East.