Health & Science
Dogs’ friendly genes
It’s a question that has beguiled scientists and pet owners for years: Why are dogs so innately friendly? New studies suggest the answer may lie in a mutation in doggie DNA that is also found in a rare human disease that makes people extremely friendly. The researchers believe that as dogs evolved from wolves over thousands of years, humans encouraged the proliferation of this genetic change in the dog population through breeding. Scientists from Oregon State University conducted a series of experiments with 18 dogs and 10 captive wolves, in which the animals had to solve a puzzle when they were alone, with someone they knew, or with a stranger. The wolves consistently outperformed the dogs and remained more focused on their task, whereas the dogs became distracted by people. Researchers at Princeton then pinpointed differences in two genes in the two sets of animals; these same two genes have been linked to Williams-Beuren syndrome in humans, which causes overly friendly behavior. Researcher Monique Udell says Williams-Beuren delays cognitive development in humans, but works for the dogs because they have learned to get what they need from people. “The very things that make life challenging for a human,” she tells The New York Times, “may make dogs successful.”
Men’s declining fertility
Sperm counts in Western men have more than halved over a period of almost 40 years, reports NBCNews.com. An international team of researchers analyzed 185 studies conducted between 1973 and 2011, involving nearly 43,000 men from North America, Europe, New Zealand, and Australia. They found that over those four decades the concentration of sperm in the men’s ejaculate dropped 52 percent, and that their overall sperm count fell 59 percent. While the recent sperm levels were still within what fertility clinics class as “normal,” the downward spiral showed no signs of leveling off. “It’s extremely worrisome,” says lead author Shanna Swan, from the Icahn School of Medicine in New York City. “For couples who are trying to conceive, this is a very severe problem, and it’s difficult psychologically. But in the big scheme of things, this is also a major public health issue.” The researchers didn’t identify the causes of the decline, but suggested that factors could include stress, poor diet, smoking, and exposure to hormone-disrupting chemicals.
Water inside the moon?
A substantial amount of water may be hidden beneath the moon’s dusty exterior, new research suggests. During the Apollo missions in the 1970s, astronauts found glass beads on the lunar surface that had formed when magma from ancient volcanic eruptions cooled rapidly. Scientists recently discovered that these beads contain about as much water as basalt, a type of volcanic rock on Earth, but it was unclear whether the samples were anomalies or representative of the whole moon. To find out, a NASA-funded team at Brown University analyzed satellite data and measured the light reflected from the moon’s surface. They detected trapped water in nearly all the volcanic deposits, suggesting that parts of the moon’s mantle could contain as much water as Earth’s. If their theory is right, co-author Shuai Li tells CNN.com, these reserves could potentially be mined to support a lunar space colony or deep-space missions. “Anything that helps save future lunar explorers from having to bring lots of water from home is a big step forward,” Li said.
Health scare of the week
The dangers of anti-vaxxers
If measles vaccination rates in the U.S. drop just 5 percent, the number of children diagnosed with the virus could triple. In a Stanford University–led study, researchers found that about 93 percent of children between 2 and 11 years old receive the MMR vaccine, which protects against measles, mumps, and rubella. They calculated that if vaccination rates drop to 88 percent—below the 90 to 95 percent needed to achieve “herd immunity”—it will lead to a total of 150 children being diagnosed with measles each year, putting them at risk for complications including pneumonia, hearing loss, and brain damage. Government health programs would also face additional costs exceeding $2 million, reports Reuters.com. Measles was eliminated in the U.S. in 2000, but the likelihood of outbreaks has increased as more parents refuse or delay vaccinations due to personal beliefs or the misguided idea that the disease no longer poses a threat. Co-author Peter Hotez, of Baylor College of Medicine, says the anti-vaccine movement in the U.S. has grown so influential that anti-vaxxers’ perceptions will likely only be shifted by “catastrophic measles epidemics.”
National Geographic, Getty, NASA/Goddard/Lunar Reconnaissance Orbiter ■