Darwin’s Surprise

Viruses. Simply the mention of these non-living microscopic particles is enough to make anyone cringe; conjuring up memories of sick days in bed.  Exposure to viruses causes infected cells to focus solely on synthesizing new virions, impairing normal cell activity causing people to feel ill. Although most people think of viruses solely as harmful,surprisingly they are an aiding factor in what makes us human.

Through extensive research performed on the human genome, scientists have discovered various endogenous and disabled retroviruses that possibly code for a variety of  functions essential to human evolution. Meaning that humans have descended from both viruses and other organisms. The discovery that evolution does not occur solely through living organism would have been a surprise to Darwin. Darwin understood that the environment played a role in influencing an organism’s evolution. However, he did not realize that an organism could evolve directly from their environment, since he lacked an understanding of viruses.  Aside from the fact that viruses play a significant part in an organism’s evolution, Darwin also would be surprised to realize that endogenous viruses prove common ancestry among organisms.

This article discusses how viruses have played an important part in our evolutionary history. When a retrovirus is able to infect a germ cell and utilize reverse transcriptase to incorporate its DNA into its host’s DNA, the virus can be perpetuated. In essence,  endogenous viruses become a part of our genes and are synthesized to carry out functions that might prove to be advantageous. But, whether something is considered advantageous or not depends on the environment. Endogenous retroviruses whose functions have proven advantageous continue to get perpetuated today.For example, prior to the evolution of mammalian births humans laid eggs, but because of expose to a retrovirus that incorporated its DNA into the DNA of a germ, cell humans developed placentas. The development of a placenta from retroviruses on the syncytium proved to be advantageous and resulted in larger brains.  This article proves that retrovirus have help shaped the human race’s evolution.

What I found most surprising was learning why humans are affected by HIV. Due to the fact that humans were closely related to chimpanzees they were affected by PtERV it became an endogenous retrovirus. Therefore, humans are vulnerable to HIV because our built-in defense to Pan troglodytes (PtERV) .  There is a gene in humans called TRIM5a that synthesizes a protein whose job it is to bind to and destroy PtERV. Unfortunately, this protein cannot protect against both HIV and PtERV it has to choose one.  

In this article I learned the beneficial qualities of viruses in shaping an organism’s evolutionary history. While I still cringe slightly at the thought of viruses I have a new appreciation for them. I think that science should revive dead viruses because they can provide us a better understanding of the mechanisms of retroviruses. This can help scientists better understand and successfully combat current viruses that are pose a threat to humans, like HIV. Additionally further research on viruses can help us understand ourselves and other species.  However, I believe that these experiments should be conducted for research purposes only in secure facilities, to prevent misuse of them.


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