Q: Opthamalogists used to believe that once a blind child passed the critical age of 6-8, his or her brain would never be able to make sense of the visual world. How did Project Prakash (Sanskrit for "light") demolish this idea?
A: Lead neuroscientist Pavon Sinha found a test "laboratory" in India with its large population of some 360,000 to 1.2 million blind children, most of whom live in poor rural areas with limited access to health care, says Rhitu Chatteejee in "Science" magazine. In 2011, Project Prakash began to correct the cataract-ridden eyes of children like Manoj Kumar Yadav, blind from birth, who at the age of 18 — well beyond the accepted cutoff age for surgery — was implanted with synthetic lenses. When the bandages were removed, Yadav "couldn't tell people from objects, or where one thing ended and another began ... But over the coming months, his brain gradually learned to interpret the signals it was receiving from his eyes, and the blurry and confusing world began to come into focus." Now at 22, he can even ride a bicycle in a crowded market.
Thus far, some 500 older children have undergone successful surgery, a testament to the plasticity of the human brain, though the newly sighted will never see as well as those born sighted. Sinha did not expect such massive changes in the brain and was amazed by just how quickly and late in life they can happen. Concludes Chatterjee: "The project has brought hundreds of young people like Yadav into the light — while putting the field of visual neuroscience in a new light, as well."
Q: When might dental plaque be a good thing — the more, the better?
A: When you're an anthropologist like Christina Warinner, who uses dental techniques to extract hidden clues about ancient health, says Megan Gannon in "Scientific American" magazine. Warinner "performs centuries-delayed dental cleanings on the likes of Vikings and Stone Age farmers... the best teeth being the ones with chunks of plaque as big as lima beans fixed to their enamel."
Why plaque? Because sticky plaque picks up just about everything in the mouth, then hardens to entomb bits of plants, pollen, bacteria, starch, charcoal, meat, textile fibers and more. As scientists have recently learned, fossilized plaque is the "richest source of DNA in the archaeological record."
A goal of Warinner's laboratory is to build a DNA inventory of plaque from increasingly diverse corpses from around the world "to find out how human health and eating habits have changed throughout history."
Q: "Get 7-9 hours of sleep each night," the experts say, but a 2013 Gallup poll pointed out that Americans average only 6.8 hours. Why are we short-changing ourselves this way? Is it the hectic postindustrial world we live in?
A: Probably not. When UCLA sleep scientist Jerome Siegel and colleagues studied the sleep habits of three different hunter-gatherer tribes — the Hadza of Tanzania, the San of Namibia and the Tsimane of Bolivia — they found averages of only 5.7-7.1 hours per night. As reported by Chris Samoray in "Science News," these results were based on over 1,000 days' worth of measurements of 94 individuals who wore watches designed to collect sleep data. "Typically, people fell asleep several hours after sunset with falling ambient temperatures and awoke before dawn as temperatures reached a low."
Yet one striking difference between the hunter-gatherers and people in postindustrial societies did emerge: Only 1.5-2.5 percent of the hunter-gatherers reported having insomnia more than once a year, while chronic insomnia rates in the postindustrial world range from 10-30 percent. "Studying sleep is more natural environments, outside of the lab and in many difference populations, may help scientists better understand problems such as insomnia."