Everyone has heard the phrase "living on the edge," mostly used to denote a risky, adventurous lifestyle. There are so many sayings like that we use on a daily basis but rarely think twice about their origins. Living on the edge is used to describe the animals that feed and graze on the fringes or outlines of a large herd. In a herd of a million zebras or a shoal of billion sardines, the creatures that live on the edge get the best food and cleanest water. They also get eaten first. Living on the edge is a natural example of the risks vs rewards principle that we're all familiar with - the higher the risk, the greater the rewards. I always knew what living on the edge meant, just never realized where it came from. I just presumed it meant something along the lines of living by the sword or the edge of knife. Animal Planet opened my eyes.