'Snails may help predict the weather'

While the story goes that if a snail climbs a plant or post, rain is coming, research led by the University of York shows "snails can provide a wealth of information about the prevailing weather conditions thousands of years ago."

The researchers analysed the chemistry of snail shells dating back 9,000 to 2,500 years recovered from Mediterranean caves, looking at humidity at different times in the past.

Their findings, reported in the journal Quaternary International, reveal that when the first farmers arrived in Italy and Spain, the western Mediterranean was not the hot dry place it is now, but warmer, wetter and stickier.

The researchers led by Dr Andre Carlo Colonese from York's Department of Archaeology believe that land snails have great potential as a source of information about human behaviour and palaeoclimatic conditions and therefore should be given much more attention.

"By putting together research on snails from multiple sites across Spain and Italy, we were able to produce a large scale regional picture for weather conditions over the western Mediterranean area," Colonese said in a statement.

"This allowed us to observe differences in climate across the region. Interestingly, when compared with previous studies, we found that while conditions on the Atlantic coast of northern Spain were probably much like those of today, on the Mediterranean side in locations such as southern Spain and Sicily, conditions were much more humid," said Colonese.

Archaeological sites around the Mediterranean basin contain an abundance of land snail shell remains

The researchers selected well-preserved shells for isotopic analysis from the early to late Holocene layers, covering the Mesolithic, Neolithic, Chalcolithic and Bronze Age periods.

They looked at the oxygen and carbon isotopic compositions of the shells of Pomatias elegans or the round-mouthed snail, comparing those found in the Iberian Peninsula sites with modern shells of the same species.