Modern Snails Reveal Ancient Human Migration Patterns Thousands of Years Ago

What do modern snails and ancient humans have in common? Not a lot genetically, but they have quite a bit in common historically. Scientists have discovered that snails may have migrated along with humans in order to colonize new territory thousands of years ago.

A particular variety of snails in Ireland and the Pyrenees are almost genetically identical, despite being thousands of miles apart. Known as the banded wood snail, these two populations have similar shell patterns and mitochondrial genes that are rarely seen in other areas of Europe. What is even more perplexing is the fact that during its apparent migration, the snail seems to have missed Britain entirely.

In order to examine the history of these snails and learn a little bit more about how they might have migrated, the scientists examined the fossil record. They found that the snail had actually been in Ireland for the past 8,000 years. In France, they found well preserved shell remnants that revealed this creature was probably once eaten regularly. Despite this evidence, though, it was almost impossible to explain the snail migration--unless you add in humans.

"There are records of Mesolithic or Stone Age humans eating snails in the Pyrenees, and perhaps even farming them," said Angus Davison, co-author of the study, in a news release. "If the snails naturally colonized Ireland, you would expect to find some of the same genetic type in other areas of Europe, especially Britain. We just don't find them."

It's likely that the snails actually hitched a ride on what was once an ancient trade route to the Atlantic as humans migrated from France to Ireland. In fact, the snails actually reveal this migration pattern.

"It's consistent with the idea that almost everything we have in Ireland that can't swim or fly was brought here on a boat," said Dan Bradley from Trinity College Dublin in an interview with BBC News.

While the snails can show us quite a bit about these ancient migration patterns, they can't tell us everything. The scientists plan to look at more ancient DNA from different species that may be able to tell them a little bit more about these movements. More specifically, they plan to look at human remains.

The findings are published in the journal PLOS One.