An accomplished young scientist solves one of the greatest mysteries of evolution: What caused the dramatic explosion of life half a billion years ago?. The Cambrian Explosion is universally referred to as biology's Big Bang. About 550 million years ago, there was literally an explosion of life forms, as all the major animal groups suddenly and dramatically appeared. Why did it happen this way? Why didn't these creatures continue the slow, plodding pace of evolution, appearing only very gradually in the fossil record? Although several books have been written about this surprising event, none have explained why it occurred. Indeed, none were able to.Here, for the first time, Oxford zoologist Andrew Parker reveals his theory of this great flourishing of life. Parker's Light Switch Theory holds that it was the development of vision in primitive animals that caused the explosion. Precambrian creatures were unable to see, making it impossible to find friend or foe. With the evolution of the eye, the size, shape, color, and behavior of animals was suddenly revealed for the first time. Once the lights were turned on, all animals had to either adapt or die, and in a geological instant, the world became a very different place. A controversial theory but one that is quickly gaining ground, the Light Switch Theory promises to revolutionize our understanding of life and light. Drawing on evidence not just from biology but also from geology, physics, chemistry, history, and art, In the Blink of an Eye is the fascinating story of a young scientist's intellectual journey, and a celebration of the scientific method.