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Editor’s Note: This story, originally printed in the September 1999 issue of Scientific American, is being posted due to a new study showing that nerve cells can be regenerated by knocking out genes that typically inhibit their growth. For Chinese gymnast Sang Lan, the cause was a highly publicized headfirst fall during warm-ups for the 1998 Goodwill Games. For Richard Castaldo of Littleton, Colo., it was bullets; for onetime football player Dennis Byrd, a 1992 collision on the field; and for a child named Samantha Jennifer Reed, a fall during infancy....

Richard Leakey, paleoanthropologist, conservationist and Kenyan political leader, died January 2 at his home near Nairobi. His expeditions discovered hundreds of hominin fossils, leading Fred Spoor, a paleontologist at the Natural History Museum in London, to tell me his findings were “a most extensive and diverse fossil record of early human evolution.”* Other scientists, conservationists, writers, artists and filmmakers have tried to get people to pay attention to current existential crises, including climate change and the sixth extinction (the predicted mass extinction of much of Earth’s life)....

With spring in full swing and Mother’s Day just around the corner, beauty is all the buzz these days. But it’s also year-round big business. As billions of dollars fuel the cosmetic industry and a host of new medical treatments boast a long list of benefits, consumers are barraged with conflicting information about possibilities, effectiveness and health. Can creams really treat cellulite? What about wrinkles? Who is making sure that all this stuff is safe?...

1970 1970 Pacific Junction “A four-week Pacific cruise this spring by the U.S. Navy research vessel DeSteiguer has produced further evidence that the earth’s crust consists of discrete drifting plates. The voyage provides an example of theory successfully predicting fact: if three oceanic plates should drift apart, a wedge-shaped area would appear on the seafloor with its apex at the triple juncture. The McKenzie-Morgan hypothesis was published jointly in 1968; it led one of W....

The main goal posts in the global fight against climate change are set in the wrong place, one researcher argues in a new paper this week. The established international target of limiting global warming to 2 degrees Celsius leaves too much wiggle room and doesn’t move the world fast enough to avert catastrophic warming, explained Oliver Geden, head of the E.U. research division at the German Institute for International and Security Affairs....

When the medical charity Médecins Sans Frontières called the worldwide shortage of snake antivenom a public-health crisis last September, Brazilian biochemist Paulo Lee Ho wasn’t surprised. He has spent his career at São Paulo’s Butantan Institute searching for better ways to create antivenom to treat bites from coral snakes. Conventional methods rely on natural coral-snake venom, which is hard to come by: the snakes produce only small amounts with each bite and are hard to raise in captivity....

A farmworker crouches in the hot Texas sun, harvesting celery for market. That evening, painful red blisters erupt across his forearms. The celery–a newly developed variety prized for its resistance to disease–unexpectedly produces a chemical able to trigger severe skin reactions. Traditional breeding methods generated this noxious vegetable. But opponents of genetically modified foods worry that splicing foreign genes (often from bacteria) into food plants through recombinant-DNA technology could lead to even nastier health surprises....

The virus touches down on the cell like a spider landing on a balloon 1,000 times its size. It has six thin legs splayed underneath a body that resembles a syringe with a bulbous head. This is a predator named lambda, and its prey is an Escherichia coli bacterium. Having found its victim, lambda now does what uncountable trillions of viruses have done since life first emerged: it latches onto the cell membrane with its legs, attaches its syringelike part to a pore and contracts, injecting its DNA inside....

Key concepts Chemistry Food Science Proteins Enzymes Introduction Have you ever poured yourself a cup of milk and instead of a smooth liquid, all you get is clumps? This is usually a sign that the milk has gone bad. And if it smells sour, it probably has. But the physical process of what happened to the milk is called coagulation, which is the mechanism that occurs when proteins in the milk clump....

Editor’s note (4/2/2017): This week marks the 100-year anniversary of the U.S. entry into the First World War. Scientific American, founded in 1845, spent the war years covering the monumental innovations that changed the course of history, from the first tanks and aerial combat to the first widespread attacks with chemical weapons. To mark the centennial, we are republishing the article below and many others. For full access to our archival coverage of the Great War sign up for an All Access subscription today....

The hopes of turning Mars into a more Earth-like planet have just taken a hit. Science-fiction writers have long dreamed of terraforming Mars—changing the frigid Red Planet’s climate to make it more suitable for human colonization. One potential way to do this involves freeing lots of heat-trapping carbon dioxide from the Martian crust back into the atmosphere. And it had been reasonable to speculate that Martian rocks might contain lots of this greenhouse gas....

Witness the following: On June 24, home plate umpire Brian O’Nora was hospitalized after the broken barrel of a bat hit him on the head during a game between the Colorado Rockies and Kansas City Royals. He suffered a mild concussion. On April 25, the barrel of a maple bat used by Colorado Rockies first baseman Todd Helton flew into the stands in Dodger Stadium in Los Angeles, hitting Susan Rhodes of Sherman Oaks, Calif....

A sedentary lifestyle has long been linked to poor health, and a growing body of evidence suggests it may also affect personality. Previous research found associations between a lack of exercise and declines in character traits such as conscientiousness, measured four to 10 years after initial surveys. Now the largest analysis of its kind to date has used longer follow-up periods to confirm these links and show they persist up to nearly two decades....

Black Man in a White Coat: A Doctor’s Reflections on Race and Medicine by Damon Tweedy Picador, 2015 (($26)) As a black doctor, author Tweedy has firsthand knowledge of how, for complicated social, cultural and economic reasons, “being black can be bad for your health.” For instance, African-Americans face an increased risk of problems such as diabetes, heart disease and stroke and an infant mortality rate twice that of whites. Tweedy experiences this sad truth from both sides of the stethoscope and relates his challenges in navigating the predominantly white medical world as a patient and a professional....

By Nicola JonesCorals around Japan are fleeing northwards, according to a new study. One type has been spotted ‘sprinting’ at 14 kilometers a year, thanks to a lift from ocean currents. That means ocean ecosystems could shift rapidly in the face of climate-change impacts such as warming seas, the authors say.The study, due to be published in Geophysical Research Letters, is the first documentation of coral mass migration, but matches up with several other observations....

U.S. EPA’s youngest social justice advisers are hammering the federal government for its lack of action on climate change. In a draft report—prepared for EPA Administrator Scott Pruitt and other agency officials—a group of outside advisers calls on the Trump administration to take action on climate change and offers tips on how to engage young Americans on the issue. “Despite the urgency of climate change, political will at the national level has lagged behind or been outright captured by the powerful interests opposed to bold and just solutions offered by young people, desperate to defend their future rights to a clean and healthy planet,” wrote the Youth Perspectives on Climate Change Work Group....

Scientists are discovering that the Arctic’s rising temperatures might be the second-biggest threat to wildlife. Climate variability is increasing, as well, meaning once-rare extreme events like flash floods and droughts happen more often. It’s difficult for wildlife to cope with these pulses; animals have responded to global warming by shifting ranges and behaviors, but these dramatic changes can come too quickly for adaptation. The impact can be brutal, according to a new study published in PLOS....

Northern Ethiopia was once home to a vast, ancient lake. Saber-toothed cats prowled around it, giant crocodiles swam within. The streams and rivers that fed it—over 3 million years ago, during the Pliocene—left behind trails of sediment that have now hardened into sandstone. Deposited within these layers are fossils: some of early hominins, along with the bones of hippos, antelope, and elephants. Anthropologist Jessica Thompson encountered two of these specimens, from an area named Dikika, in 2010....

Silicon has transformed the digital world, but researchers are still eager to find substances that will make integrated circuits smaller, faster and cheaper. High on the list is graphene—planar sheets of honeycomb carbon rings just one atom thick. This nanomaterial sports a range of properties—including ultrastrength, transparency (because of its thinness) and blisteringly fast electron conductivity—that make it promising for flexible displays and superspeedy electronics. Isolated only four years ago, graphene already appears in prototype transistors, memories and other devices....

The following essay is reprinted with permission from The Conversation, an online publication covering the latest research. Every day countless headlines emerge from myriad sources across the globe, both warning of dire consequences and promising utopian futures – all thanks to artificial intelligence. AI “is transforming the workplace,” writes the Wall Street Journal, while Fortune magazine tells us that we are facing an “AI revolution” that will “change our lives.” But we don’t really understand what interacting with AI will be like – or what it should be like....