Health & Science

Hope in the HIV battle

Of the 33 million people worldwide living with HIV, two-thirds are in Africa, and most of the new infections there occur among women and schoolgirls. But a newly tested vaginal gel finally offers hope against the scourge, says the Los Angeles Times. The colorless, odorless, inexpensive gel contains tenofovir, a medication widely used to treat AIDS. A two-year clinical trial in South Africa found that among women who used the gel at least 80 percent of the time, the number of HIV infections was cut by more than half. It’s the first time a gel containing a microbicide has been found to work against HIV, and its success means that women no longer need to rely solely on men to wear a condom. “It can be controlled by women, and put in 12 hours earlier, and that is empowering,” says Michael Sidibé, executive director of the United Nations’ AIDS-fighting unit. “They do not have to ask the man for permission to use it.” In a separate study sponsored by the World Bank, researchers found that giving small cash payments—a few dollars a month—to the families of poor schoolgirls offered enough economic freedom that the girls had sex later, less often, and with fewer partners. After 18 months, those girls in turn were 60 percent less likely to become infected by HIV.

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Mercury, the smallest planet and the one nearest to the sun, still has a few surprises. Newly analyzed data from NASA’s Messenger spacecraft, which recently flew within 142 miles of the planet’s surface, reveals that Mercury is “much more dynamic than people appreciated,” principal investigator Sean Solomon tells The New York Times. One new feature, the 180-mile-wide Rachmaninoff crater, is filled smooth with lava that cooled as recently as a billion years ago; scientists previously assumed that all volcanic activity had ceased shortly after the planet formed, 4.5 billion years ago. Messenger also measured fierce magnetic storms, as the planet is buffeted by particles streaming from the sun. Next spring, the spacecraft will again approach Mercury and make a series of orbits. “We’re really looking forward to the orbit phase,” says NASA space physicist James Slavin. “It might be quite a treasure trove.”

The origin of sperm

Male animals of all stripes, from sea anemones to men, produce sperm. That’s more than evolutionary coincidence; scientists have now found that one of the genes responsible for generating sperm dates back 600 million years, to the common ancestor of humans, fish, insects, and even slimy sea creatures. Researchers at Northwestern University found that the gene, called the Boule gene, can be found across the evolutionary spectrum, from worms to fish to flies to mammals. The discovery suggests that disrupting the Boule gene in insects and animals could prevent them from breeding, and thus offers a new way to combat germs, parasites, and pests. The gene, researcher Eugene Xu tells NationalGeographic.com, is also “an ideal target” for the long-sought male birth control pill.

Shrimp on Prozac

Nobody’s giving the crustaceans a prescription for Prozac, but shrimp consume antidepressants anyway, in the runoff of human waste that feeds into estuaries and other waterways where shrimp congregate. Shrimp don’t get a lift from the drugs, a new study finds; instead, they become reckless, and abandon the darker waters where they are less visible to predators and seek sunny, bright areas instead, which puts them in danger. “This behavior makes them much more likely to be eaten by a predator, such as a fish or bird,” study co-author Alex Ford, a biologist at the University of Portsmouth in England, tells NationalGeographic.com. Prozac makes the shrimp’s nerves more sensitive to serotonin, a brain chemical known to alter moods and sleep patterns. The chemicals likely affect a range of fish, but the researchers “focused on shrimp because they are common and important in the food chain,” Ford says; endanger the shrimp, and the whole ecosystem stands to suffer.

A tomb sealed for 1,600 years

Archaeologists working at a site in Guatemala have unexpectedly unearthed the well-preserved tomb of an ancient Mayan king, says LiveScience.com. The team had been poking beneath an established pyramid when it broke open a hole in the floor; lowering a bare light bulb revealed “an explosion of color in all directions—reds, greens, yellows,” says lead researcher Stephen Houston. The tomb dates from about A.D. 350 to 400 and held the remains of a richly adorned man, likely a dynasty leader, as well as ceramics, textiles, bowls of human fingers and teeth, and the bones of six children, who may have been sacrificed when the king died. The tomb was so well sealed from both water and air that when Houston opened it, “there was still, to my astonishment, a smell of putrefaction and a chill that went to my bones.” Interpreting the site, which is dense with material and information, will likely take years.