The evolution of the human eye has long been regarded as a contentious issue. It was believed to be an example of irreducible complexity – that is something that could not have evolved, because any precursor to the fully evolved form would be non-functioning. Wikipedia gives a good overview of the concept. This lesson shows that not only do evolutionary precursors to the eye exist, but that there is a huge diversity in the structure and function of eyes in the animal kingdom.

An ophthalmologist in America, Tim Root, has created a great video on the evolution of the eye, exploring it in more detail, with some great animation.

The study of the evolution of the human eye not only a worthwhile in itself, but as a platform to explore evolution as a whole, the diversity of the animal kingdom, adaptation and so on. Scientific American recently ran an article on the evolution of the human eye and the interesting questions raised by the history of our eyes.

The study of the evolution of other structures in the animal kingdom is equally interesting. Scientist Carl Zimmer wrote an interesting article on the evolution of the human eye, and has created a TED-Ed Lesson: How did feathers evolve?

One of the subjects introduced in this lesson is the idea of biomechanical implants. To find our more have a look at this MIT technology review, Bionic Eye Implant Approved for U.S. Patients. The Scientific American article, Retinal Implants Deliver the Promise of Sight to Damaged Eyes provides a more detailed discussion on this topic.

Interested in learning more about the eye? Watch the following TED Ed lessons:
Why do we cry? The three types of tears - Alex Gendler
What are those floaty things in your eye? - Michael Mauser
How we see color - Colm Kelleher

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