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NEW YORK—The prevailing view among astronomers used to be that Mercury, the smallest and innermost planet in the solar system, was a static and unevolving world, baked to infernal temperatures by its proximity to the sun. Mariner 10, the first spacecraft to fly by Mercury, offered some tantalizing evidence of volcanic activity in 1974 and 1975. Now MESSENGER, a NASA spacecraft that has passed by Mercury in the past year and will go into orbit in 2011, has confirmed Mariner 10’s observations by imaging young lava plains indicative of recent volcanic activity on the planet....

Polar bears diverged from brown bears surprisingly recently—within the past 500,000 years, researchers report today in Cell. Previous studies suggested that the separation occurred between 600,000 and 5 million years ago. The latest analysis compares the complete nuclear genomes of 79 polar bears from Greenland with those of 10 brown bears from a variety of locations: Sweden, Finland, Montana and three islands off the coast of Alaska, Admiralty, Baranof and Chichagof....

By Zoë Corbyn of Nature magazine A fossil of a plesiosaur, an extinct marine reptile, has revealed that not only did these animals give birth to live young, they may also have cared for their offspring in a manner similar to today’s whales and dolphins. The 78-million-year-old fossil, of a four-flippered giant belonging to the species Polycotylus latippinus, had lain unexamined in a museum basement for nearly 25 years. Other extinct marine reptiles, such as ichthyosaurs, mosasaurs and choristoderans, were known to give birth to live young, a strategy called viviparity....

Key concepts The human eye Peripheral vision Central vision Introduction Do you only think of your peripheral (side) vision—peripherally? This side vision is actually useful for many daily activities, including riding a bike, reading or playing basketball. You might not even realize when you are using it. But our survival once depended on the quick response of our peripheral vision. A detailed picture, created by our central vision, is only useful in situations where time allows us to focus on the details....

Editor’s note: The following essay is reprinted with permission from The Conversation, an online publication covering the latest research. Since the spectacular discovery of the Higgs boson in 2012, physicists at the Large Hadron Collider (LHC), the gigantic particle accelerator outside Geneva, have suffered a bit of a drought when it comes to finding new particles. In a welcome relief, the LHCb collaboration, who run one of four large experiments at the LHC, have announced one of the most genuinely exciting observations to come out of the 27km super-collider so far – an exotic particle that cannot be explained by current theories....

The baiji is gone. During six weeks of searching the Yangtze River, scientists and conservationists failed to spot any of the unique creatures. This means, they say, that the “goddess of the Yangtze” is extinct because, even if a scattered few are still around, there are not enough to reproduce and perpetuate the species. “Our inability to detect any baiji in the main channel of the river despite this intensive search effort has the sad consequence that the prospect of finding and translocating any surviving dolphins to an ex situ reserve—their only conservation hope—has all but vanished,” says zoologist Samuel Turvey of the Zoological Society of London....

After each of the presidential debates, the media has scrambled to decide, among other things, which of the two candidates was more truthful. The fact-checkers worked hard, attempting to establish if anything President Obama or Governor Romney said was inaccurate. However, it isn’t as if the rest of us waited for the morning paper to make our own judgments. Whether watching the debates, viewing the commercials, or reading campaign literature, we always have a sense for how truthful a politician candidate is....

In South Africa they have a problem, a big one: too many elephants. For most of the 1900s extensive poaching threatened to wipe out the country’s elephants. In response, conservationists established reserves throughout the region and relocated as many herds as they could. Now those herds are doing quite well. So well, in fact, that they’re causing problems. Wildlife managers are currently facing a dilemma: how to deal with too many elephants....

What turns a young female concerned mainly about herself into a good mother who will make sure her offspring survive in an otherwise hostile world? The bodily changes of childbearing are obvious, but as we are discovering, the changes in the brain are no less dramatic. The maternal brain is a formidable object, a singular entity forged by hormones, neurochemicals, and exposure to the ravening demands and irresistible cuteness of offspring....

Strange things have happened in the media in recent years. In 2017 members of the Trump administration alluded to a “Bowling Green massacre” and terror attacks in Sweden and Atlanta that never happened. The misinformation was swiftly corrected, but some historical myths have proved difficult to erase. Since at least 2010, for example, an online community has shared the apparently unshakable recollection of Nelson Mandela dying in prison in the 1980s, despite the fact that he lived until 2013, leaving prison in 1990 and going on to serve as South Africa’s first Black president....

Editor’s Note: The World Wide Web went live 20 years ago this month, on a single computer in Geneva, Switzerland. For the anniversary the Web’s inventor, Tim Berners-Lee, has written an exclusive article for Scientific American. In it he confronts various threats that could ruin the Web, and explains why preserving the basic principles that have allowed the Web to flourish is essential to preventing its destruction. While preparing the article, Berners-Lee also spoke to Scientific American about emerging Web capabilities that could change how the online and physical worlds work....

By Ian Simpson WASHINGTON (Reuters) - The United States’ top doctor said that medical marijuana can help some patients in comments on Wednesday that may boost pressure on the Justice Department to redesignate the drug under federal law. In an interview on “CBS This Morning,” U.S. Surgeon General Vivek Murthy said the medical effectiveness of marijuana had to be shown scientifically and much more information about it was coming. “We have some preliminary data showing that for certain medical conditions and symptoms, marijuana can be helpful,” said Murthy, who became surgeon general in December....

By Sharon WeinbergerCould publishing a scientific article constitute an act of economic espionage? That question lies at the heart of charges against a Massachusetts-based scientist accused of passing U.S. trade secrets to China.Ke-xue Huang, a Canadian citizen and permanent U.S. resident, was arrested on July 13, and has been charged under a law designed to protect intellectual property held by U.S. companies. At a bail hearing last week in Massachusetts, the U....

According to the Oxford English Dictionary’s first definition, a “skeptic” is “one who holds that there are no adequate grounds for certainty as to the truth of any proposition whatever.” This is too nihilistic. There are many propositions for which we have adequate grounds for certainty as to their truth: There are 84 pages in this issue of Scientific American. True by observation. Dinosaurs went extinct around 65 million years ago....

In the world of diplomacy, India may be remembered for its last-minute push to downgrade coal language at this year’s climate talks. But India’s importance in the global transition away from fossil fuels is significant for other reasons. It is the world’s third-largest carbon polluter and also a rapidly expanding economy, meaning the amount of greenhouse gases it will continue to send into the atmosphere is only likely to keep growing as its population does....

Honeybee stings ache for a good reason: This species knows how to brawl. But as it turns out, these black-and-yellow pollinators are quite vulnerable themselves—especially to neonicotinoids, a pesticide commonly used to ward off crop-munching pests. Two new studies, published this week in Science, address this question by studying large populations of bees in multiple locations for months on end. The results add substantial weight to the claim that neonicotinoids damage bee populations....

A new report warns that the exploding usage of radio waves by broadband-devouring smartphones and video threatens to deplete a finite wireless spectrum. “If you look at traffic patterns over the past five years, we went from things like illegal music downloads, to legal music downloads, to video,” said technology adviser and report author Michael Kleeman at University of California San Diego. “Video is the primary driver of Internet usage in the United States....

Aggressive optimism. Those two words capture the spirit of Earth 3.0 and, we hope, the spirit that Washington, D.C., will bring to urgent energy, environment and sustainability issues. Right now a new president is calculating his administration’s first steps. If he is serious about ending U.S. dependence on oil, stopping climate change and reversing destruction of land and sea, he has to take strong actions in his first 100 days. Shirley Ann Jackson, president of Rensselaer Polytechnic Institute, talks straight about what those actions should be....

Every month, SCIENTIFIC AMERICAN—the longest-running magazine in the U.S. and an authoritative voice in science, technology and innovation—provides insight into scientific topics that affect our daily lives and capture our imagination, establishing the vital bridge between science and public policy. Key information from this month’s issue: • ALZHEIMER’S Many neuroscientists have greeted the Obama administration’s goal of preventing or treating Alzheimer’s by 2025 with skepticism, but the $50-million funding provided by the National Alzheimer’s Project Act may make finding a treatment a realistic goal....

Some theorists believe infants enter the world with “hard-wired” neurons that are preadapted for both understanding and producing speech. Others believe that speech is learned through experience. Now research reveals how a baby’s speech centers function at five days old, then six months, then a year. Neuroscientist Patricia Kuhl of the University of Washington, working with colleagues at the University of Helsinki in Finland, used a new technique, magnetoencephalography (MEG), to measure brain activity by sensing the magnetic fields neurons create when they fire....