DALLAS, Oct. 28 (UPI) — U.S. scientists say fossil land snail shells found on the subtropical eastern Canary Islands suggest that area was much wetter in the past.
Southern Methodist University researchers said the fossils show the Spanish archipelago off the northwest coast of Africa has become progressively drier during the past 50,000 years.
Professor Roy Huffington and post-doctoral researcher Yurena Yanes said isotopic measurements performed on the fossil snail shells produced oxygen isotope ratios suggesting the relative humidity on the islands was higher 50,000 years ago, then decreased to the time of maximum global cooling and glaciation about 15,000 to 20,000 years ago.
With subsequent post-glacial climatic fluctuations, relative humidity seems to have oscillated somewhat, but finally decreased even further to modern values, the scientists said.
The researchers said their finding advances understanding of the global paleoclimate during an important time in human evolution, when the transition from gathering and hunting to agriculture first occurred in the Middle East and subsequently spread to Asia, North Africa and Europe.
“The results of this study are of great relevance to biologists and paleontologists investigating the evolution of plants and animals linked to climatic fluctuation in the islands,” Yanes said.
He presented the research last week In Portland, Ore., during the annual meeting of The Geological Society of America.
Copyright 2009 by United Press International