Archivo: Science

Mars’s methane has gone missing. Scientists first detected traces of the gas—a critical indicator of life on Earth—in the planet’s atmosphere decades ago. But today, researchers reported that a European satellite hasn’t spotted a single trace of methane. The finding, if it holds up, could complicate scientific dreams that martian microbes might be spewing the gas in the planet’s subsurface.

Australia’s splendid assassin fly (Blepharotes splendidissimus) earns its fearsome moniker. About the size of a bottle cap and sporting a similar metallic luster, they ambush butterflies and dragonflies in midair, killing them with a venomous bite. Now, scientists have discovered that even the larvae of these flies are vicious.

Growing up in South Texas, David Pfennig was fascinated by cannibalistic tadpoles. When summer storms soak the normally dry plains, spadefoot toads emerge from their burrows to lay eggs in short-lived pools. The tadpoles normally dine demurely on algae, tiny crustaceans, and detritus. But even as a boy, Pfennig could tell that the same toads sometimes spawned very different tadpoles. Those tadpoles had bulging jaw muscles and serrated mouthparts. They jostled aggressively in the shrinking puddles. They ate larger crustaceans, such as fairy shrimp—and one another.

Unlike most cells in our bodies, the neurons in our brain can scramble their genes, scientists have discovered. This genome tampering may expand the brain’s protein repertoire, but it may also promote Alzheimer’s disease, their study suggests.

During the Cambrian, which began about 540 million years ago, nearly all modern animal groups—as diverse as mollusks and chordates—leapt into the fossil record. Those early marine animals exhibited a dazzling array of body plans, as though evolution needed to indulge a creative streak before buckling down. For more than a century, scientists have struggled to make heads or tails—sometimes literally—of those specimens, figure out how they relate to life today, and understand what fueled the evolutionary explosion.

Ask medieval historian Michael McCormick what year was the worst to be alive, and he’s got an answer: “536.” Not 1349, when the Black Death wiped out half of Europe. Not 1918, when the flu killed 50 million to 100 million people, mostly young adults. But 536. In Europe, “It was the beginning of one of the worst periods to be alive, if not the worst year,” says McCormick, a historian and archaeologist who chairs the Harvard University Initiative for the Science of the Human Past.

We know the menagerie of microbes in the gut has powerful effects on our health. Could some of these same bacteria be making a home in our brains? A poster presented here this week at the annual meeting of the Society for Neuroscience drew attention with high-resolution microscope images of bacteria apparently penetrating and inhabiting the cells of healthy human brains. The work is preliminary, and its authors are careful to note that their tissue samples, collected from cadavers, could have been contaminated. But to many passersby in the exhibit hall, the possibility that bacteria could directly influence processes in the brain—including, perhaps, the course of neurological disease—was exhilarating.

Daubed in orange ochre at least 40,000 years ago, images of what appear to be wild cattle on the Indonesian island of Borneo are now the oldest known figurative paintings in the world. Painted in a remote limestone cavern, they are more than 4000 years older than the previous record holders on nearby Sulawesi, and they add to evidence that thriving artistic traditions were emerging simultaneously in Europe and Asia.

Early humans faced countless challenges as they fanned out of Africa: icy conditions, saber-tooth cats, and, according to a new study of ancient skeletons, an unusually high number of birth defects, both debilitating and relatively inconsequential. It’s unclear why such abnormalities seem to be so common, but scientists say one strong possibility is rampant inbreeding among small hunter-gatherer groups.

The shape of a mother’s birth canal is a tug-of-war between two opposing evolutionary forces: It needs to be wide enough to allow our big-brained babies to pass through, yet narrow enough to allow women to walk efficiently. At least that’s been the common thinking. But a new study reveals birth canals come in a variety of shapes in women around the world.