Snail Reveals Mystery Behind Irish Migration
Geneticists from Ireland unearthed new evidence of an ancient human migration from the Pyrenean region of France to Ireland, by examining snails.
The snails (Cepaea nemoralis) from both Ireland and the Eastern Pyrenees region along the Spainsh-French border have large, white-lipped shells share genetic markers that are extremely rare elsewhere in Europe.
"It's interesting to use snail genetics to find out how snails colonize, and it also maybe gives us a little insight into what humans were doing, too," says Angus Davison, an evolutionary geneticist at the University of Nottingham in the United Kingdom.
"One really neat thing about this study is that, if we accept that humans transported snails, it really gives us a unique insight into an individual journey 8000 years ago, and it gives us evidence of that from a source you might not imagine."
Biologists have been wondering for a long time how various wildlife species that exist in Ireland, are mysteriously not found in neighboring Britain but found in Iberia, the peninsula that includes modern-day Spain, Portugal and parts of France.
In order to solve this mystery, Davison and colleague Adele Grindon analyzed a distinctive-looking snail that had the same one-inch long shells in both locations. According to fossil evidence, the snails first showed up in Ireland about 8000 years ago. The molluscs had lived in southern Europe for tens of thousands of years before that.
"You would think that anything that gets to Ireland would go through Britain, but it has been a longstanding mystery as to why Ireland is so different from Britain. For these snails, at least, the difference may be that they hitched a ride on a passing boat," Davison said.
Out of 900 snails they studied, they extracted mitochondrial DNA, which is passed directly from mother to offspring, and they looked at specific areas of the genome that are known to vary from snail species to snail species.
Based on the results, Davison suspects,people brought the snails with them as they moved. Ancient people may have intentionally brought the snails as a source of food on the trip. Alternatively, the snails may have hitched a ride in the grassy fodder packed for other animals.
"I think this study is important in that it does conclusively show that there is some link with Spain based on this snail," says says Allan McDevitt, a geneticist at University College Dublin. "It's the most definitive proof yet that this is actually a very real migration that was happening."