View full lesson: http://ed.ted.com/lessons/the-evolution-of-the-human-eye-joshua-harvey The human eye is an amazing mechanism, able to detect anywhere from a few photons to a few quadrillion, or switch focus from the screen in front of you to the distant horizon in a third of a second. How did these complex structures evolve? Joshua Harvey details the 500 million year story of the human eye. Lesson by Joshua Harvey, animation by Artrake Studio.