From Science's Online Daily News Site

摘要

There may be more to a cat's purr than meets the ear. A new study reports that our feline friends modify their signature sound when seeking food, adding a higher-frequency element that exploits our sensitivity to infant wails-and thus making it harder to ignore.rnIt has become almost common wisdom that the virus that caused the 1918 flu pandemic was an avian strain introduced into the human population shortly before the pandemic erupted. But a new study disputes that hypothesis, arguing instead that genes of the 1918 virus had circulated in mammalian hosts, most likely pigs and humans, for several years before 1918. Multiple gene-swapping events brought them together in a single killer strain, say the researchers; improving surveillance in humans and in swine could, in the future, give scientists an early alert to such events.