ADVERTISEMENT Cutting off the horns of sedated rhinos with a chainsaw has been viewed by wildlife conservationists in Africa for more than 30 years as a necessary evil to save the iconic endangered species from poaching. They hoped the drastic action was working, but evidence was scarce. Now, a study published Thursday in the academic journal Science has found that dehorning rhinos has led to a large reduction in poaching in game reserves in and around the Kruger National Park in northern South