 If you were faced with the task of sawing off another person's arm or leg, you'd want all the correct tools, and certainly a doctor by your side. But doing it out in the wild with no help, it just sounds pretty much impossible. So what about just biting it off? Well, that's the tried and tested method of ants, which apparently has a 90% success rate, and it's not as stressful as it might sound. Swiss biologist Laurent Keller is co-author of the study.