From sharks to giraffes, many of Earth’s biggest and most magnificent species are threatened with extinction. A new study of the fossil record indicates that once large vertebrates disappear, evolution cannot quickly restore them — for tens of millions of years, most animals remain small.

The study, published Thursday in Science, emerged from research carried out by Lauren Sallan, a paleontologist at the University of Pennsylvania.

Studying fish that lived during the Mississippian Period, from 359 million to 323 million years ago, she noticed that they were substantially smaller than their ancestors.

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A mysterious die-off of endangered antelopes last spring in Central Asia was even more extensive than originally thought, killing more than half of the entire species in less than a month, scientists have found.

“I’ve worked in wildlife disease all my life, and I thought I’d seen some pretty grim things,” Richard A. Kock, of the Royal Veterinary College in London, said in a telephone interview. “But this takes the biscuit.”

At a scientific meeting last week in Tashkent, Uzbekistan, Dr. Kock and his colleagues reported that they had narrowed down the possible culprits. 

Continue reading “More Than Half of Entire Species of Saigas Gone in Mysterious Die-Off” →

Scores of leading scientists on Wednesday urged the creation of a major initiative to better understand the microbial communities critical to both human health and every ecosystem.

In two papers published simultaneously in the journals Science and Nature, the scientists called for a government-led effort akin to the Brain Initiative, a monumental multiyear project intended to develop new technologies to understand the human brain.

“This is the beginning of the shot to the moon,” said Jeffery F. Miller, the director of the California NanoSystems Institute at the University of California, Los Angeles, and a co-author of the Science paper. “There is so much to learn, and so many benefits of learning it.”

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Researchers have long wondered how people settled the Americas, particularly the path they took to the new territory and the timing of their expansion. Until recently, archaeologists studying these questions were limited mostly to digging up skeletons and artifacts.

But now scientists have begun extracting DNA from human bones, and the findings are providing new glimpses at the history of the first Americans. On Monday, researchers at the University of Alaska and elsewhere published an important addition to the growing genetic archive.

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Bacteria can change history.

In the 14th century, a microbe called Yersinia pestis caused an epidemic of plague known as the Black Death that killed off a third or more of the population of Europe. The long-term shortage of workers that followed helped bring about the end of feudalism.

Historians and microbiologists alike have searched for decades for the origins of plague. Until now, the first clear evidence of Yersinia pestis infection was the Plague of Justinian in the 6th century, which severely weakened the Byzantine Empire.

Continue reading “In Ancient DNA, Evidence of Plague Much Earlier Than Previously Known” →