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Editor’s note: This essay, by renowned evolutionary biologist Lynn Margulis, was published in the August 1994 issue of Scientific American with the title, “Sex, Death and Kefir.” Margulis died on Tuesday in her home, according to a statement released by the University of Massachusetts at Amherst, where she was a Distinguished University Professor of Geosciences. She is best known for her work on how symbiosis led to the evolution of organelles, which were once independent organisms (she describes her theory in her August 1971 Scientific American article “Symbiosis and Evolution” (pdf), which you can read if your library has an institutional subscription)....

Dear EarthTalk: The U.S. Environmental Protection Agency had its 40th anniversary in 2010. How effective has the EPA been and what are its biggest challenges today?—Bill A., Seattle, Wash. By most accounts the U.S. Environmental Protection Agency (EPA), which turned 40 in December 2009, has been very effective. The first dedicated national environmental agency of its kind, the EPA has been instrumental in setting policy priorities and writing and enforcing a wide range of laws that have literally changed the face of the Earth for the better....

The National Park Service was established a century ago this August to protect the U.S.’s natural treasures, historic sites and national monuments. In this essay collection, writer and conservationist Williams chooses 12 of the 410 places that fall under the National Park Service’s protection, reflecting on both the history and power of these locales and their personal meaning to her. For instance, Williams grew up exploring Grand Teton National Park with her family and worked at the Teton Science Schools....

By Alla Katsnelson A strategy for lowering heart-disease risk that once seemed to be a dead end is showing fresh promise. Decades of animal studies and epidemiological data had suggested that raising blood levels of high-density lipoprotein–HDL, or “good” cholesterol–might have a stronger protective effect against heart disease than statins, drugs that lower levels of low-density lipoprotein (“bad” cholesterol or LDL). But in 2006, a $1-billion trial of torcetrapib, an HDL-raising drug, found it seemed to increase patients’ risk of death, casting a pall of doubt over the entire field....

Governments will need authoritative scientific analysis if they hope to boost their future climate change targets, the head of the Intergovernmental Panel on Climate Change said. In an interview with ClimateWire, Chairman Hoesung Lee said the pledges that countries have made up to 2030 at the U.N. climate negotiations in Paris will not, by themselves, avoid severe climate change. More ambition would be needed, post-2030, to ensure temperature rise in 2100 remains below 2 degrees Celsius....

It’s no secret we at Scientific American are fans of the kinds of bold ideas that can help take humanity to a better future. Recently technology, especially digital, seems to be advancing more swiftly than ever. Noting the trend, even the policy leaders at the World Economic Forum’s Davos meeting this year focused on the theme of the “Fourth Industrial Revolution.” How do you know what emerging technologies are likely to make the most difference?...

NASA launched its Juno probe on August 5 from Cape Canaveral Air Force Station in Florida. The mission will be a meeting of mythological mates, as Juno is named after the queen of the Roman gods and has been sent to enter orbit around the planet named after Juno’s husband Jupiter. The planetary probe left Earth carried by an Atlas 5–Centaur rocket. An hour after liftoff it jettisoned the Centaur upper stage, which gave it its final boost, to proceed toward Jupiter alone....

By Nicola Jones of Nature magazineTwo scientists from New Zealand will travel to Antarctica on December 28 in a quest to continue a 100-year-long record of Earth’s magnetic field: a record begun by British explorer Robert Scott at the start of his ill-fated expedition to the geographic south pole (see “Turning the world upside down”).Record-keeping is necessary because the magnetic poles move about, thanks to the complex circulation of Earth’s fluid outer core....

Semiconductor crystals known as quantum dots have long held the promise of improving solar cells, lasers and lighting fixtures, but the reality is that integrating these fluorescent nanoparticles into existing technologies has proved difficult. One Silicon Valley start-up now aims to change this by the end of next year using quantum dots to vastly improve the picture-taking quality of cell phone cameras. The secret, according to Menlo Park, Calif.–based InVisage Technologies, Inc....

Inheritance: How Our Genes Change Our Lives—and Our Lives Change Our Genes Sharon Moalem Grand Central Publishing, 2014 Imagine you are at a dinner party with your spouse, but you can’t keep your eyes off the host, enthralled as you are by the curve of her neck. For many, this might warrant a heated spousal talking-to. And so it does for Moalem, a specialist in rare genetic disorders, though not for the reasons you might think....

Ganymede, get ready for your close-up. No probe has gotten a good view of Jupiter’s largest moon since 2000, when NASA’s Galileo spacecraft swung past the strange world, which is the largest moon in the whole solar system. But on Monday (June 7), at 1:35 p.m. EDT (1735 GMT), NASA’s Juno spacecraft will skim just 645 miles (1,038 kilometers) above Ganymede’s surface, gathering a host of observations as it does so....

The baiji dolphin is functionally extinct, orangutans are disappearing and even some species of bats—the most numerous of mammals—are dying out. A new survey of the world’s 5,487 mammal species—from rodents to humans—reveals that one in four are facing imminent extinction. “Mammal species that are just declining, not necessarily near extinction, that’s 50 percent,” says conservation biologist Jan Schipper of the International Union for Conservation of Nature (IUCN), which keeps the Red List of Threatened Species....

Researchers recently found that a female killer whale could copy the phrases “hello,” “bye-bye,” “Amy,” and “one, two, three.” The orca could also imitate a wolf’s howl, an elephant’s trumpeting, and the sounds of a creaking door and a “raspberry.” And she reproduced the new sounds quickly, some within the first attempt. Orcas are known to communicate amongst themselves using an array of sounds, and the animals have even demonstrated “dialects”—variations in communication signals that are specific to certain groups of the animals—the scientists reported in a new study....

Do more pine beetles mean more groundwater? Perhaps—but that’s not necessarily a good thing, say the authors of a new study. The bark beetle outbreak that has plagued North America’s Rocky Mountains is having significant ripple effects on the region’s hydrology, researchers from Colorado’s School of Mines in Golden, Colo., report in a study published this week in the journal Nature Climate Change. Compared with a watershed where a beetle infestation’s impacts were less intense and occurred less recently, a watershed with more beetle-killed trees absorbs about 30 percent more groundwater, the researchers found....

Spring never has been more welcome. After more than a year of isolation, spirits across the country are being reinvigorated by daffodils, birdsong and longer days. In the western United States, however, this change of mood of may be tempered by a recent publication in Science that reported regional declines in the abundance of butterflies—normally another welcome harbinger of seasonal renewal. If these lovely animals vanished from the United States tomorrow, many of us would feel a profound aesthetic loss....

This is the third of eight stories in our Web feature on self-experimenters. Of the thousands of malaria-ridden mosquitoes that have bitten Stephen Hoffman over the years, he is most grateful to a batch of 3,000 that feasted on his arm in the mid-1990s. The swarming bloodsuckers had been subjected to radiation to weaken the malaria-causing parasitic Plasmodium falciparum sporozoites they carried. The result: he became immune to the disease that kills at least one million people yearly, most of them children, in sub-Saharan Africa and elsewhere....

Researchers have deciphered the molecular structures of two of the brain’s crucial lock-and-key mechanisms. The two molecules are receptors for the natural neurotransmitter serotonin — which regulates activities such as sleep, appetite and mood — and could provide targets for future drugs to combat depression, migraines or obesity. “This is huge,” says Bryan Roth, a neuropharmacologist at the University of North Carolina Chapel Hill Medical School, and a co-author of the two studies published in Science today....

A picture really is worth a thousand words. In the December Scientific American science writer Zach Zorich reports on the discovery of a spectacular artwork in the ancient Maya city of Holmul in Guatemala. The find is helping archaeologists figure out how two Maya superpowers functioned during a long-running war. For more on the Maya, check out the resources below. “Drought May Have Brought on Demise of the Maya,” by Sarah Graham “Ancient Time: Earliest Mayan Astronomical Calendar Unearthed in Guatemala Ruins,” by John Matson “New Find Pushes Back Date of Maya Writing,” by David Biello “The Earliest Maya,” by Norman Hammond “Maya Writing,” by David Stuart and Stephen D....

In every bit of nothing, there is something. If you zoom in on empty space and take out all the planets and stars and galaxies, you might expect a pure vacuum, but you’d be wrong. Instead you would find a dynamic scene, with particles sparking to life and disappearing almost immediately. Quantum mechanics, the theory governing the infinitesimal world, doesn’t allow for nothingness. At any given moment in time and space, energy can never be perfectly zero—there is always some wiggle room....

Gridlocked bridges over the Fraser River are just a part of life for commuting Vancouverites. But the industrialized motif of North America’s longest dam-free river belies a rare natural treasure: a sockeye salmon run with a historical average of eight million fish worth over $1 billion. Since the early 1990s the numbers of Fraser sockeye have steadily dwindled, reaching a particularly troublesome nadir in 2009 when more than 11 million sockeye were forecast to return and only 1....