Health & Science

The world’s despoiled oceans

Pollution and overfishing have damaged 96 percent of the world’s oceans, leaving only the polar seas largely pristine, says a worldwide sea ecology study. More than 40 percent of the oceans has been seriously fouled by sewage, garbage, pesticides, and other chemicals contained in runoff, as well as by overfishing and by construction along the shoreline, which has wiped out mangrove forests, marshes, and other sea-cleansing vegetation. The most serious and widespread problem, though, is that the seas are becoming more acidic, as they absorb the increasing amounts of carbon dioxide that human activities are releasing into the atmosphere. Acidic seas can kill off key kinds of plankton and can destroy coral reefs, which are vital to marine life. Even polar seas are now feeling the encroachment of human activities. “Every single spot in the oceans was affected by at least one human activity,” study author Ben Halpern tells the Associated Press. The pervasiveness of the damage shocked the survey team, because “we figured there’d be places people just hadn’t gotten to yet.”

Exploring the G spot

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In laboratories and bedrooms all over the world, scientists and amateurs have sought the elusive G spot, the sensitive area of the vaginal canal that can induce a non-clitoral female orgasm. But many of those efforts have gone unrewarded—until now. Using ultrasound scans, Italian physicians have found a key difference in the anatomy of women who say they experience orgasms through sexual intercourse alone. When they scanned the urethrovaginal space—the area in the front of the vaginal canal rich in blood vessels, glands, muscle fibers, and nerves—they found that the tissue there was significantly thicker. This thickened region appears to be the G spot. Only about 25 percent of women appear to have thicker, more sensitive tissue there. The study “would help explain the fact that most women do not reliably have orgasm through intercourse,’’ women’s sexuality expert Elisabeth Lloyd of Indiana University told New Scientist. She and other experts think, however, it may be possible to create G spot tissue in a woman by stimulation, or by hormone treatment.

The telltale hair

Scientists have come up with a new forensic technique that can trace a person’s movements across the country from the chemical makeup of his or her hair. “You are what you eat and drink, and that is recorded it your hair,” researcher Thure Cerling tells LiveScience. Every locale has its own water source, and every water source has its own signature mixture of hydrogen and oxygen isotopes. By analyzing the differences in isotopes along a strand of hair, and comparing those isotopes to a water map of the United States, forensic examiners can trace a person’s travels throughout the country and determine when, approximately, he was in each place. (Even people who mostly drink bottled water consume tap water through coffee or in pasta or other foods cooked in water.) The technique could be invaluable to police examiners attempting to identify a murder victim, or to verify the location of a criminal suspect within a certain time frame. The method does, however, have its limitations. “You can tell the difference between Utah and Texas,” Cerling says. But “you may not be able to distinguish between Chicago and Kansas City.”

Sad news about antidepressants

They’re the most commonly prescribed medications in the U.S., with more than 118 million prescriptions written each year. But antidepressants, says a new study, are no more effective in relieving most users’ depression than a placebo. British researchers came to this startling conclusion by combing through data from 47 published and unpublished clinical trials of such drugs as Prozac and Paxil, also known as SSRIs (selective serotonin reuptake inhibitors). They found that drug companies had been selective in reporting the results of SSRI studies, and that overall, the data showed that these medications produced significant mood improvements only in the most severely depressed patients. For the majority of patients, the medications were not significantly more effective than taking a sugar pill. The findings suggest that antidepressants often work not because they change the chemistry of the brain but because people expect them to—the “placebo effect.” Previous studies have found that talk therapy and regular exercise are just as effective as SSRIs in relieving mild depression.

Study author Irving Kirsch of the University of Hull in the U.K. tells BBCnews.com that there is no scientific basis to prescribe antidepressants to anyone not suffering from severe depression. He said the study “raises serious issues surrounding drug licensing and how drug trial data is reported.” Drug companies say that Kirsch had failed to recognize that millions of people had “very positive” results from the medications, and that his conclusions “were at odds with what has been seen in clinical practice.”