科学美国人60秒:Missing Snail Trail Fosters Migration Theory

A population of snails in Ireland shares genetic traits and physical characteristics with another population in the Pyrenees. And you hardly ever find such snails elsewhere in Europe. So how did they make the hop without leaving any obvious trail? Researchers now think that Stone-Age humans carried the creatures by sea some 8,000 years ago. The analysis is in the journal PLoS ONE. [Adele J. Grindon and Angus Davison, Irish Cepaea nemoralis Land Snails Have a Cryptic Franco-Iberian Origin That Is Most Easily Explained by the Movements of Mesolithic Humans]

The critters in question are a variety of banded wood snails. Birds sometimes move meals long distances, but no known migration route covers these two areas. People are thus the most likely travelers to pick up a snail in the south of France and drop it in Ireland.

Fossil records suggest snails in the Pyrenees were part of the diet of Mesolithic humans. And the river that flanks the Pyrenees is known to have been a trade route to the ocean. The researchers conjecture that migrating humans brought them on the voyage to Ireland either accidentally or for an escargot snack. A fate that some snails escaped to found the population there today.

—Dina Fine Maron