Ricky Wang
Author: Emory University
Published: December 18th, 2014
Human color vision have changed a lot due to genetic mutations in our ancestors over the last couple millions of years. Scientists have traced back 90 million years of vision evolution that led to our current human vision and discovered that five classes of opsin genes codes for visual pigments for dim-light and color vision. These opsin genes changes depending on the environment and vision adapts as well. 30 million years ago, human ancestors evolved four classes of opsin genes, giving them the ability to see the full color spectrum of visible light except for UV. There are 5040 combinations of amino acid changes to create the genetic changes. Each possibility was tested, and it is found out that the evolutionary pathway is only completed when several genetic changes combine in a particular order. Human vision evolution took a long time, probably because the human environment has changed very slowly.
This article connects primarily to our evolution unit. First, we learned about adaptation and natural selection in chapter 14. Human vision, along with our ancestors’ vision is a trait and has followed natural selection and has adapted over millions of years to the changes of the environment. The best suited individuals for the environment are more fit. For example, our ancestors that were able to see more colors clearly were probably more likely to survive, reproduce, and pass along those genes to their offspring. On the contrary, our ancestors that had a dim and shadowy view of the world would probably have been less fit and less likely to survive. Additionally, this also connects to our unit on genetics specifically about how different combinations of amino acids can result in a variety of outcomes. These differentiations in amino acids make up the genetic changes that accounts for the visual pigments and ultimately, the evolution of human vision.
Firstly, what are opsin genes, and secondly if the environment of the Earth were to change rapidly, how would this effect human vision evolution?
ReplyDeleteOpsins are protein receptors that sense molecules outside the cell and are located in the retina. For the second part of your question, it would really depend on how the environment were to change. For example, if the changing environment favored people that can see broader wavelengths caused by a mutated gene, then through natural selection, more people will inherit that trait.
DeleteWere there any drastic changes that improved the human vision?
ReplyDelete