Did the weather do them in?

Homo sapiens may not have pushed Neanderthals to extinction, as some scientists have hypothesised; it may have been the weather that did them in. Volcanic eruptions thousands of years ago devastated Neanderthals in Western Asia and in Europe, anthropologists report in Current Anthropology. Naomi Cleghorn, anthropologist at the University of Texas at Arlington, and colleagues studied a Neanderthal site in the Caucasus Mountains of southwestern Russia. They were able to identify volcanic ash from two eruptions that occurred in the area between 45,000 and 40,000 years ago. Recently, a separate study found that there was another large volcanic eruption in Italy 40,000 years ago, in an area also occupied at the time by Neanderthals. Our own species was primarily in Africa and southern Europe, areas less affected by the eruptions. Neanderthals were concentrated in Asia and Europe. About 2,000 years after the volcanic events, humans appear to have moved into parts of Europe previously occupied by Neanderthals, the anthropologists say. “We would like people to look more carefully at other Neanderthal sites and to look more carefully for events like this,” Cleghorn said.

Sindya N Bhanoo, New York Times News Service

A third of world’s frogs, toads endangered
From the summit of Bishop Pass in the Sierra Nevada, elevation 11,972 feet, all you can see are miles of granite peaks against the sky. There is no traffic and no pollution. The natural world seems pure and unspoiled. But appearances are deceiving. Over the last decade, disaster has struck in the form of chytridiomycosis, or chytrid, a deadly fungal disease that has driven at least 200 of the world’s 6,700 amphibian species to extinction. One-third of the world’s frogs, toads and salamanders are threatened. Forty percent are declining. Chytrid’s arrival has laid waste to the indigenous Sierra Nevada yellow-legged frog, Rana sierrae.

In Dusy Basin, a remote glacial valley in Sequoia and Kings Canyon National Parks a few miles west of Bishop Pass, Vance Vredenburg, a professor of biology at San Francisco State University, is conducting an experiment he hopes will help preserve what remains of these once abundant creatures. Vredenburg and his colleagues are inoculating chytrid-infected frogs with a bacteria, Janthinobacterium lividum, or J liv, that does not prevent infection with chytrid but can help frogs survive. Vredenburg, Reid Harris of James Madison University in Harrisonburg, Va., and colleagues found the symbiotic bacteria on several amphibian species.

Lab experiments last year showed that J.liv produces a metabolite, violacein, that is toxic to the chytrid fungus. Vredenburg wants to see how effective the treatment will be in the wild.

The Sierra frog population had been severely reduced by the California Department of Fish and Game’s practice of seeding high-elevation lakes with hatchery-raised fingerling trout for the sport fishing industry.

Chytrid has hastened the destruction. Vredenburg and colleagues counted 512 populations scattered among the thousands of mountain lakes in the park in 1997. In 2009, 214 of these populations had gone extinct. A further 22 showed evidence of the disease.

Erica Rex, New York Times News Service

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