Aşıklı Höyük (Turquie): How Sheep Became Livestock

Source - http://news.sciencemag.org/archaeology/2014/04/how-sheep-became-livestock

Roman Neumüller/Creative Commons

Bringing the animals home. Farmers at this prehistoric Turkish village penned their sheep in between their mudbrick houses.

The domestication of plants and animals was one of the most important events in human history, but rarely have archaeologists been able to catch the process in the act. Now, research at an 11,000-year-old settlement in Turkey shows that some early farmers kept wild sheep penned up in the middle of their village—thus setting the stage for the dramatic changes that led to today’s domesticated animals.

Archaeologists studying the origins of farming have hundreds of sites to choose from across the Middle East, but few of them tell the full story. That requires a spot that spans the transition between a hunting and gathering lifestyle and a farming lifestyle, a period from about 10,500 to 9500 years ago. Researchers have long had their eyes on just such a site: Aşıklı Höyük, located on the banks of the Melendiz River in central Turkey—a land of idyllic streams and dramatic volcanic formations popular with tourists.

Earlier work had suggested that Aşıklı Höyük might be a center of the earliest stages of animal domestication. The new study, led by zooarchaeologist Mary Stiner of the University of Arizona in Tucson, confirms this. The team looked at an archaeological layer radiocarbon dated to between 10,400 and 10,100 years ago. The botanical remains from this level show intensive cultivation of cereals, lentils, and nuts, meaning that crop farming was already under way; but the spectrum of animal bones in the earliest parts of this layer reflects the hunting of a wide variety of wild animals including hares, tortoises, and fish, along with larger animals such as goats, wild cattle, deer, and sheep. The most abundant large animal was sheep, although they represented less than half of the total animals.

Moreover, the sheep bones from these early levels were clearly those of wild animals, which can be distinguished from domesticated animals by their larger size and the distribution of ages and sexes: Wild herds, left alone by humans, tend to include more older animals and a roughly equal number of males and females.

Beginning about 10,200 years ago, however, the proportions of wild animals in this layer began to change, as the team reports online this week in the Proceedings of the National Academy of Sciences. The hunting of smaller animals appears to fall off to insignificant numbers, while the percentage of sheep—which outnumber goats by three to one—steadily increases. By about 9500 years ago, sheep represented nearly 90% of all animals at the site. Moreover, the researchers say that the age and sex pattern of the bones indicate active management, or herding, of the sheep: Only about 11% of the females died before the age of 6 to 7 months, whereas 58% of the males did, a typical pattern that reflects farmers’ desire to preserve females for breeding.

So where were these herded-yet-still-wild sheep kept? The archaeological smoking gun for animal herding is dung deposits in or near a village, and the team found ancient dung in bountiful quantities between the closely packed houses of the settlement. Moreover, under the microscope, Stiner and her colleagues were able to confirm that the dung—rich with traces of grasses, sedges, rushes, and other things that sheep like to eat—came straight out of the animals, rather than being mixed with other ingredients to make mudbricks, mortar, or fuel for fires. That means the dung was the result of stabling rather than reuse by humans for other purposes.

The team concludes that the sheep were kept captive in the village itself, even though the animals were still “morphologically wild”—that is, they had not yet undergone the reduction in size typical of domestic animals. They probably remained “behaviorally wild” as well; that is, they had yet to become the docile, sheeplike animals we know today—although the team suggests that some animals might have been introduced into the village while still very young, as pets for children.

So why did the villagers need to pen up sheep when they were already successfully hunting them? Stiner and her co-workers suggest that Aşıklı Höyük’s location by the Melendiz River, in a region with fertile soils ideal for crop farming, tempted early farmers to settle down and establish a permanent village. The downside of settlement would have been less time for roaming farther away to hunt the meat they still needed in their diet. That “scheduling conflict” between hunting and farming was best solved by bringing the sheep to the village rather than villagers going out to find the sheep, the team says. Thus, the findings provide a new glimpse into the ways that early farmers might have inadvertently begun to domesticate animals, possibly by choosing to stable less aggressive animals and thus favoring genetic variants that eventually led to domesticated varieties.

“It is wonderful to see these data starting to come out,” says Nerissa Russell, a zooarchaeologist at Cornell University. Jean-Denis Vigne, a zooarchaeologist at the National Museum of Natural History in Paris, agrees. “We have long suspected a kind of early [animal] management at Aşıklı, and we were waiting for new data to support this perspective.”

But Melinda Zeder, a zooarchaeologist at the Smithsonian Institution’s National Museum of Natural History in Washington, D.C., questions some details of the study, including whether the team was able to accurately determine the sex of the sheep—which was done by examining their pelvis bones—especially in young animals. Zeder also disagrees with the team’s contention that the herding of sheep was a response to a scheduling conflict once the people at Aşıklı settled down; rather than facing a conflict, Zeder says, they may have found a new way to take fuller advantage of both the rich plant and animal resources available in the region around Aşıklı Höyük.

And although Russell agrees that “scheduling conflicts would have been a major issue in the transition to agriculture,” she questions to what extent herding sheep would have helped solve them. “Herding would have required new kinds of labor and posed its own scheduling and labor allocation issues,” she says.