A variety of snails common in western Ireland may have been transported there by humans during the Stone Age, a new study suggests. Cepaea nemoralis, the banded wood snail, is found in many locales in Western Europe and is typically 1.5 centimeters across, about the width of an adult's thumbnail.
But a subpopulation of the species found in western Ireland ranges up to twice that size and has a distinctive white lip on its shell to boot—traits also seen in members of the species from southern France, along the northern slopes of the Pyrenees. In previous studies, carbon-dating of shells revealed that the normally rare, white-lipped variant arrived in Ireland more than 8,000 years ago.
Now, geneticists have linked the Irish snails to the Pyrenees. As they report online today (June 19) in PLOS ONE, they found that one particular lineage of the species—with two exceptions, both associated with snails found along the coasts of the Irish Sea—were found only in Ireland and in the central and eastern Pyrenees.
How the snails reached Ireland but apparently skipped intermediate regions has long been a mystery. It's most likely, the researchers suggest, that the rare white-lipped variant of the snail hitched a ride with traders traveling from the Mediterranean region through the Pyrenees on their way to Ireland—perhaps unintentionally, in fodder for the trader's animals or, more intriguingly, as a part of the trader's food supplies.
French cuisine, after all, has long been famed for its escargot.
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