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Francis Horne, a biologist who studies shell formation at Texas State University, offers this answer. The exoskeletons of snails and clams, or their shells in common parlance, differ from the endoskeletons of turtles in several ways. Seashells are the exoskeletons of mollusks such as snails, clams, oysters and many others. Such shells have three distinct layers and are composed mostly of calcium carbonate with only a small quantity of protein–no more than 2 percent....

A 5.0-magnitude earthquake struck near Cushing, Oklahoma, this evening (Nov. 6) at 7:44 p.m. local time, according to the U.S. Geological Survey. The epicenter of the earthquake was 1.8 miles (2.8 kilometers) west of Cushing and nearly 54 miles (87 km) northeast of Oklahoma City. Though no injuries have been reported, several buildings in Cushing were damaged, according to the local fire department, as reported by ABC News. [The 10 Biggest Earthquakes in History] More temblors The shaking comes on the heels of the state’s largest earthquake on record—a 5....

The world is watching as the largest outbreak of Middle East Respiratory Syndrome (MERS) outside the Middle East continues in South Korea. According to the most recent figures from the World Health Organization, 30 people have been infected, two of whom have died. Hundreds of schools have been closed. The causal coronavirus, MERS-CoV, is one of many viruses that are considered potential pandemic threats. But experts do not consider this outbreak, in which all cases are hospital-associated, to have pandemic potential or even expect it to spread further within South Korea....

Mexico’s Supreme Court on Wednesday gave the green light to growing marijuana for recreational use in a landmark decision that could lead to legalization in a country with a bloody history of conflict with drug cartels. Supporters of reform sparked up joints to hail the court’s decision, which, while not legalizing use of marijuana, is one of the boldest steps ever taken in that direction in a country long reluctant to liberalize drug laws....

ANXIOUS WORLD Nerve: Poise Under Pressure, Serenity Under Stress, and the Brave New Science of Fear and Cool by Taylor Clark. Little, Brown, 2011 ($25.99) What is the most common mental health issue in America? You might be tempted to say depression. But you would be wrong. According to the Centers for Disease Control and Prevention, anxiety disorders now take the top spot, with 18 percent of Americans suffering from one....

Bubonic plague, smallpox, polio, HIV—the timeline of history is punctuated with diseases that have shaped the social atmospheres of the eras, defined the scope of science and medicine, and stolen many great minds before their time. But there is one disease that seems to have stalked humanity far longer than any other: tuberculosis. Fossil evidence indicates that TB has haunted humans for more than half a million years. No one is exempt....

Scientists have pieced together the first-ever global topographic map of Titan, Saturn’s largest moon, using radar observations from veteran NASA spacecraft. The new map of Titan was stitched together from radar observations of the moon by NASA’s Cassini spacecraft. It reveals an unprecedented look at Titan’s surface and should help scientists learn more about one of the most Earth-like bodies in the solar system, members of the mapping team said....

On a dark night in the late ’80s Alejandro Alagón was working in his garden near Cuernavaca, Mexico, when he felt a sharp pain in his hand while moving a rock. He flipped the stone over and saw an especially poisonous scorpion squashed beneath it. Another person might have headed immediately to the hospital. But Alagón, a molecular biologist and antivenom researcher, happened to have just the right treatment at home....

In 1927 the aviation world marveled at Charles A. Lindbergh’s nonstop flight from New York to Paris. Lindbergh was in it for more than thrills: he was after the $25,000 Orteig Prize. In a 21st-century encore, the 12-year-old nonprofit X Prize Foundation conceives and manages competitions for daring innovators. The foundation’s game plan is to define an exciting target that benefits humanity, bait it with a large stack of cash, and draw out the best in design and invention from private, nongovernmental teams....

What’s killing the bees? If you’ve been watching the news, you might answer: “Colony collapse disorder.” Yet after the winter of 2011-2012, beekeepers only attributed 8 percent of their wintertime honeybee-hive losses to colony collapse disorder. Other reasons for hive deaths were much more common, including ailing queen bees, to which beekeepers attributed 32 percent of their dead hives. At one recent pollination research conference, nobody seemed to be looking for the disorder’s cause anymore....

Severe flooding in India and wildfires in Colorado provided a backdrop of recent examples of weather-related disaster yesterday, as scientists and policymakers discussed the science of severe weather events at the American Geophysical Union’s annual science policy conference in Washington, D.C. The panel discussion led off with a straightforward yet disturbing fact: In 2012, the United States had the world’s two costliest disasters, totaling more than $100 billion. One was Superstorm Sandy, and the other was the yearlong Midwest drought....

Once hunted to the brink of extinction for their luxuriant pelts, California sea otters rebounded after protections were put in place in 1911. Their population grew steadily for much of the last century, but now the still threatened species is stuck at about 3,000 otters. The problem is that they are boxed in at both ends of their current range, along the state’s central coast, by a sharp (and so far unexplained) rise in shark attacks....

Stress is a killer—at least for brain cells. A new animal study shows that a single socially stressful situation can destroy newly created neurons in the hippocampus, the brain region involved in memory and emotion. Although most of the brain stops growing by adulthood, new nerve cells are continually generated in the hippocampus, where they are essential for learning. Scientists have long known that chronic stress can inhibit this neurogenesis and lead to depression....

Welcome to the Multiverse By Alexander Vilenkin The universe as we know it originated in a great explosion that we call the big bang. For nearly a century cosmologists have been studying the aftermath of this explosion: how the universe expanded and cooled down, and how galaxies were gradually pulled together by gravity. The nature of the bang itself has come into focus only relatively recently. It is the subject of the theory of inflation, which was developed in the early 1980s by Alan Guth, Andrei Linde and others, and has led to a radically new global view of the universe....

So what do you think?” said Lee Berger. He had just opened the lids of two big wooden boxes, each containing the carefully laid out fossilized bones of a humanlike skeleton from Malapa, South Africa. These two individuals, who had drawn their last breath two million years ago, had created quite a stir. Most fossils are “isolated” finds—a jawbone here, a foot bone there. Scientists then have to figure out whether the pieces belong to the same individual....

You knew this was going to happen. You just didn’t know how quickly. No, I’m not describing the script of every porn movie ever made (though I am). I’m talking about the fact that there is already a Google Glass porn movie in the can. I am grateful to the Verge for discovering that the famous porn star James Deen has already shot a movie with Google Glass. More Technically Incorrect...

Kristina Carlson didn’t think much about the tick she pulled off her torso while she was hiking in the mountains of North Carolina in September 2020. But back home in Mississippi a month later, Carlson complained to her doctor of aching joints and a bloated feeling in her stomach. Her doctor ruled out rheumatoid arthritis, and a blood test didn’t turn up anything definitive. Then Carlson started having eye infections. In February 2021 she suddenly found a strange rash on her face; an urgent-care facility doctor treated her for shingles, but the rash didn’t get better....

To choose the entrants in this year’s emerging technologies report, we convened a steering group of world-renowned technology experts. The committee made recommendations and elicited suggestions from members of the Forum’s Expert Network and Global Future Councils, Scientific American’s board of advisers and others who are tuned in to burgeoning research and development in academia, business and government. Then the group whittled down the choices by focusing on technologies that were not yet widespread but were attracting increased funding or showing other signs of being ready to move to the next level....

In the summer of 2003 Washington University in St. Louis sued one of its former researchers, prostate cancer specialist William Catalona, for ownership of tissue samples collected from thousands of his patients over the years. To some of those patients, Catalona was the sole intended recipient of the specimens, and the university’s actions were inconsistent with the research to which they had consented. This spring a St. Louis judge ruled in favor of the university, raising questions about the adequacy of informed consent practices....

Did you like this interview? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. Over the course of several millennia, textiles were the primary form of aesthetic expression and communication for the diverse cultures that developed throughout the desert coasts and mountain highlands of the Andean region. Worn as garments, suspended on walls of temples and homes, and used in ritual settings, ancient Andean textiles functioned in multiple contexts, yet, within each culture, the techniques, motifs, and messages remained consistent....