Navigation Links
Scientists find fossil proof of Egypt's ancient climate

Earth and planetary scientists at Washington University in St. Louis are studying snail fossils to understand the climate of northern Africa 130,000 years ago.

While that might sound a bit like relying on wooly bear caterpillars to predict the severity of winter, the snails actually reveal clues about the climate and environment of western Egypt, lo those many years ago. They also could shed light on the possible role weather and climate played in the dispersal of humans "out of Africa" and into Europe and Asia. Periods of substantially increased rainfall compared to the present are known to have occurred in the Sahara throughout the last million years, but their duration, intensity, and frequency remain somewhat unconstrained.

Jennifer R. Smith, Ph.D., Washington University assistant professor of earth and planetary sciences in Arts & Sciences, and her doctoral student Johanna M. Kieniewicz, are using stable isotope and minor element analyses of the freshwater gastropod Melanoides tuberculata and carbonate silts from a small lake (now dry) in the Kharga Oasis of western Egypt to reconstruct climatic conditions during the lifetime of the lake. Their analyses support a surprising picture of arid Egypt: 130,000 years ago, what everyone considers an eternal desert was actually a thriving savannah, complete with humans, rhinos, giraffes and other wild life.

Evidence for the hominin presence abounds near the lake in the form of Middle Stone Age artifacts such as stone scrapers and blades.

"The artifacts provide a record that people were coming to the lake," said Smith. "Genetic evidence suggests that 100,000 to 400,000 years ago was a critical time in the evolution and dispersal of African hominins. Our climate data from this 130,000-year-old humid event suggest that this would have been a particularly good time for a northward migration through Africa following reliable water resources, since it seems to be the strongest humid phase in this region over the past 400,000 years. We're also testing the hypothesis that humid events were more frequent than previously thought, which would have allowed for greater mobility throughout the region."

The researchers noted that the silt thickness at the lake exceeds five yards, an indication that the humid phase lasted at least several thousand years. Normal rainfall in the area they study is a minuscule 0.7 of a millimeter per year, but there is evidence that the rainfall amounts in the region have gotten up to as much as 600 millimeters per year, "not enough to make it a paradise," Smith said, "but enough to turn a barren environment into a classic savannah."

Kieniewicz performed isotopic analyses of about 20 snails, all of them dating to the humid phase, which occurred approximately 130,000 years ago. These particular snails have a life span of between one and two years, and build their shells in a classic spiral with whatever water is available that day. The snails were preserved in calcium carbonate deposits throughout the lake.

"We're using the chemistry of the water over the course of a year or two, as revealed by isotopic analyses and minor element analyses of the snail shells to determine information about the climate then," Kieniewicz said. "The shell is an archive of the snail's life. The analyses give us snapshots of what the conditions were like in that lake basin."

The geochemical analyses confirmed that the water was a stable standing body for many years. "Strong evaporation of the lake, enough to shrink it substantially in volume and make it more saline would have been expected to result in large excursions in d18O and minor element concentrations," Kieniewicz said. "However, throughout the stratigraphy, the d18O values of the silts remain isotopically light and the minor elements do not show intense evaporative trends, suggesting that the lake remained stable and fresh."

Smith and Kieniewicz attended th e 116th annual meeting of the Geological Society of America, held Nov. 7-10 in Denver. Kieniewicz presented a paper there on their findings.

Smith's specialty is geoarchaeology, which uses classic earth science methods and concepts to address questions of archaeological interest.

"In this particular study, we're interested in building a history of climate change through time to understand how people would have responded to dramatic shifts in climate," said Smith. "This is a major theme of our work, and we hope that some of our findings can give us perspective on what we're facing in the coming centuries."


'"/>

Source:Washington University in St. Louis


Related biology news :

1. Scientists ID molecular switch in liver that triggers harmful effects of saturated and trans fats
2. Scientists Replicate Hepatitis C Virus in Laboratory
3. Scientists detect probable genetic cause of some Parkinsons disease cases
4. Scientists find missing enzyme for tuberculosis iron scavenging pathway
5. Scientists seek answers on what activates deadly anthrax spores
6. Yale Scientists Find MicroRNA Regulates Ras Cancer Gene
7. Scientists collaborate to assess health of global environment
8. Scientists decipher genome of fungus that can cause life-threatening infections
9. Scientists discover the cellular roots of graying hair
10. Scientists rid stem cell culture of key animal cells
11. Scientists develop new color-coded test for protein folding
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:6/3/2016)... , June 3, 2016 ... von Nepal hat ... Lieferung hochsicherer geprägter Kennzeichen, einschließlich Personalisierung, Registrierung ... in der Produktion und Implementierung von Identitätsmanagementlösungen. ... Ausschreibung im Januar teilgenommen, aber Decatur wurde ...
(Date:6/2/2016)... --  The Weather Company , an IBM Business (NYSE: ... in which consumers will be able to interact with IBM ... voice or text and receive relevant information about the product ... have long sought an advertising solution that can create a ... and valuable; and can scale across millions of interactions and ...
(Date:6/1/2016)... June 1, 2016 Favorable Government ... Administration and Criminal Identification to Boost Global Biometrics System ... released TechSci Research report, " Global Biometrics Market ... Forecast and Opportunities, 2011 - 2021", the global biometrics ... 2021, on account of growing security concerns across various ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... N.C. (PRWEB) , ... June 27, 2016 , ... ... commercial operations for Amgen, will join the faculty of the University of ... as adjunct professor of strategy and entrepreneurship at UNC Kenan-Flagler, with a focus ...
(Date:6/24/2016)... on a range of subjects including policies, debt and investment ... Speaking at a lecture to the Canadian Economics ... the country,s inflation target, which is set by both the ... "In certain areas there needs to be frequent ... not sit down and address strategy together?" He ...
(Date:6/24/2016)... NC (PRWEB) , ... June 24, 2016 , ... Researchers ... the most commonly-identified miRNAs in people with peritoneal or pleural mesothelioma. Their findings are ... to read it now. , Diagnostic biomarkers are signposts in the blood, lung ...
(Date:6/23/2016)... Mass. , June 23, 2016   ... development of novel compounds designed to target cancer ... napabucasin, has been granted Orphan Drug Designation from ... the treatment of gastric cancer, including gastroesophageal junction ... stemness inhibitor designed to inhibit cancer stemness pathways ...
Breaking Biology Technology: