Fearful facial expressions are protective trait
The look of fear is unmistakable: wide eyes, raised brows, a dropped jaw. But is it more than a social signal? In the journal Nature Neuroscience, University of Toronto researchers reported that fearful expressions evolved to heighten the senses and improve detection of physical threats. Scientists asked 20 college students to assume fearful and neutral faces and measured their field of vision each time. Fearful expressions enlarged the vision field by 7.6 per cent compared with a neutral expression, presumably making it easier to spot an attacker. Scientists also measured eye movements and found that increased scanning took place when students’ expressions mimicked fear. “When you’re fearful, you need to gather as much information as possible,” said lead author Joshua M. Susskind, a graduate student in psychology. In another experiment, scientists found that squinting the eyes in an expression of disgust narrowed the field of vision from a neutral facial position by 8.9 per cent. In addition, eye movements slowed. “Disgust is a protective mechanism to withdraw from the environment,” Susskind said. The facial reactions were useful to primitive humans, who faced continual danger from the environment.
One big drug test: A city’s raw sewage can put a number on its vices
Which city uses more cocaine: Los Angeles or London? Is heroin a big problem in San Diego? And has Ecstasy emerged in rural America? Environmental scientists are beginning to use an unsavoury new tool—raw sewage—to paint an accurate portrait of drug abuse in communities. Like one big, citywide urinalysis, tests at municipal sewage plants in many areas of the US and Europe, including Los Angeles County, have detected illicit drugs such as cocaine, methamphetamine, heroin and marijuana. Since people excrete chemicals in urine and flush it down toilets, measuring raw sewage for street drugs can provide quick, fairly precise snapshots of drug use in communities, even on a particular day. The results have been intriguing: Methamphetamine levels in sewage are much higher in Las Vegas than in Omaha and Oklahoma City. Los Angeles County has more cocaine in its sewage than several major European cities. And Londoners apparently are heavier users of heroin than people in cities in Italy and Switzerland. The new practice of testing sewage has illuminated an environmental threat: Many urban waterways around the world are contaminated with low doses of cocaine and other illicit drugs from treated sewage.
