Saturday, May 28, 2016

Homologous traits in many organisms in the eye

The eyes, or at least the proteins used for eyes, is similar in all organisms. The first use of eyes was simply to detect the presence or the absence of life. Over time, the development of eyes became more complex and more useful in creating images.

Eyes from different species hold different combinations of cones and rods, but the proteins that make them are the same. Opsins are present in all organisms that use eyes or once did (the blind mole rat still has opsins, but modified for a different function).

In contrast, the lens used for the full development of eyes are composed of different proteins. However, the process of creating lens from a different combination of proteins is homologous in different species of animals. It's an example of convergent evolution, the development of lens for each species is the same however the building materials are different.

It's unique that the eyes are both homologous yet completely different.

Land, Michael F., and Russell D. Fernald. "The evolution of eyes." Annual review of neuroscience 15.1 (1992): 1-29.

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