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Ancient farmers and hunter-gathers may have traded pigs, study finds

August 28, 2013|By Melissa Pandika
  • In northweestern Europe, hunter-gatherers may have acquired domestic pigs from neighboring agricultural communities, according to a study published Tuesday in the journal Nature Communications. The pigs' coats might have looked similar to that of this modern-day Bentheimer pig.
In northweestern Europe, hunter-gatherers may have acquired domestic… (Ben Krause-Kyora / Christian-Albrechts…)

How did ancient Europeans make the switch from hunting and gathering their food to raising it on farms? They learned it from their neighbors, German archaeologists say -- and they’ve got the pigs to prove it.

Archaeologists have argued for decades over whether the hunter-gatherers who lived along the western Baltic coast 14,000 years ago had much interaction with agricultural communities in northwestern Europe. Members of the so-called Ertebølle culture had been hunting seals and wild boar when farmers migrated from the Middle East and settled nearby, bringing domesticated animals such as sheep, goats, cattle and pigs with them.

The two communities seem to have maintained distinct cultures, although recent evidence suggests that they occasionally traded stone tools and pottery. But whether hunter-gatherers adopted farming practices from their neighbors has remained “hotly debated,” archaeologists from Christian-Albrechts University in Germany and other institutions wrote Tuesday in the journal Nature Communications.

To settle the debate, the researchers sequenced DNA from the bones and teeth of 26 pigs excavated from three Ertebølle sites to determine whether they came from the same herds that agricultural communities were raising further south.  

The researchers first analyzed a short segment of DNA that’s known to be correlated with geographic origin. The sequence shows that wild boars have European ancestry while domesticated pigs are from the Middle East. They were first raised in the Fertile Crescent, an area that includes present-day Syria, Turkey and Iraq.

The DNA from the three pigs recovered in Ertebølle settlements had Middle Eastern lineage. This was a clear sign that the hunter-gatherers acquired the pigs from their agricultural neighbors, the archaeologists wrote.

The researchers then looked at a gene called MC1R, which influences coat color in pigs. Wild boars have dark gray fur that helps them blend in with their surroundings and avoid predators. In contrast, domesticated pigs typically have spotted, multicolored fur. Among the three pigs with Middle Eastern ancestry, one had light fur with dark spots. That pig must have come from Ertebølle's farmer neighbors, the researchers wrote.

Finally, they compared the molars of ancient pigs to those of modern pigs. Two of the ancient pigs had molars large enough to be considered wild. But the shapes of their molars were characteristic of domestic pigs.

Interpreting the morphology, or appearance, of remains like teeth is tricky, said study leader Ben Krause-Kyora, an archaeologist at Christian-Albrechts. That’s why his group also looked at DNA.

“We have these three lines of evidence which we can compare to conclude that these animals are domestic,” Krause-Kyora said.

Using radiocarbon methods, he and his colleagues determined that the pigs lived around 4900 to 4400 BC. Those dates suggest that domestic animals were living in northern Europe roughly 500 years earlier than archaeologists had previously estimated.

The new findings shed light on how ancient humans shifted from hunting and gathering to farming. Trading livestock might have represented “an initial step for domestication” in hunter-gatherer societies, Krause-Kyora said.

Why Ertebølle hunter-gatherers would want domestic pigs remains a mystery, although they may have been drawn to their spotted coats, which looked “strange and exotic” compared with the gray fur of wild boars, the researchers wrote.

But some archaeologists are skeptical. It’s possible that the pigs the researchers labeled as domestic were actually the offspring of domestic pigs that had escaped and bred with wild boars, said Peter Rowley-Conwy, an archaeologist at Durham University in England who wasn’t involved in the study. Their DNA would have still showed domestic ancestry.

“Those aren’t domestic pigs,” he said. “Those are wild boars with feral ancestors.”

Still, the study highlights how advances in DNA sequencing technology are revealing a more complex picture of how human societies developed, Rowley-Conwy said.

“We’re in for about 20 years of confusion — really exciting confusion — until we get enough of this analysis,” he said.

Return to Science Now.

melissa.pandika@latimes.com

Twitter: @mmpandika

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