Unseen but Always There

Charles Darwin has always been characterized as the father of evolution. Not for being the ultimate creator of the universal process but for providing a mechanism for it. Darwin primarily based his mechanism on nature, where nature selects for an individual with the most advantageous traits. He further established that there is descent with modification, where the famous “Humans evolved from apes.” line came to be. However, Darwin did not know about random mutations given his time frame (1850’s), this would lead to the implication that there might be other elements he might have missed or simply could not have access to when it came to evolution. The most significant piece being: the Virus.

It would be to Darwin’s surprise that evolution does not just occur through living organisms, but through endogenous viruses within the human DNA. Endogenous viruses are composed of broken and disabled retroviruses. This here is seen as a critical point because without access to molecular biology principles, Darwin would not have the required academic knowledge to even begin to decipher the correlations between endogenous viruses and the evolution of humanity. Today, biochemists have come to define and discover the role of viruses due to completion of the human genome map.

Having to see a retrovirus for what they truly are was the first piece that surprised me from “Darwin’s Surprise” The idea of a virus often comes with a negative connotation: a host cell is infected bringing harm to the organism. However, this article made me see beyond the virus. I was able to see a retrovirus as a gene. A gene that has helped make humans human. It was fascinating to see why something commonly perpetuated came to be: the live birth. The live birth is often seen for it’s face value, not as being an advantageous process. However, how did the live birth come to be? The answer as wild as it may seem is that due to retroviruses humans do not lay eggs. The retrovirus led to the distinction (even evolution) between a human and a reptile or fish. With endogenous retroviruses mammals were able to develop the placenta. Without a placenta a fetus would be unprotected and would not have time to reach maturity.  This is a gigantic advantage for the human species for unlike the egg, having a live birth allows for waste to be eliminated and provides nutrients from the mother to pass on to her baby.

What becomes even more shocking as like Darwin hypothesized: the human and ape/chimp are very close relatives. Beyond their outer structure and morphology if we look at the two on a molecular level we find even more similarities. The retrovirus further backs up his claim. In the early 1970’s (after Darwin’s time) biologists were able to see that on baboon placentas there were retroviruses on the syncytium. This did not prove to be in any way harmful and was soon discovered in other animals  that had live births. This would seem as something very advantageous. Don’t you agree?

Furthermore, the article shocked me when it provided an explanation for why the human’s most recent relative: the chimp, has such distinct symptoms towards HIV versus when humans gets infected by it. It was discovered that the chimp had about a hundred and thirty copies of of the virus, pan troglodytes endogenous retrovirus. Humans, on the other hand, did not have any copies of this retrovirus. This led to the hypothesis that the retrovirus, PtERV, might have to do with the intensity of HIV on it’s host. Humans had developed a protein called TRIM5a that protected it from PtERV,  but like anything in science this process came with a cost. The process by which we become protected from PtERV is the reason why we are vulnerable to HIV.

Scientists tried to modify TRIM5a but its was unsuccessful. You would either be protected from HIV or PtERV but you could never be safe from both. This made me think about the relationship of sickle cell anemia and malaria. A small change (modification) in hemoglobin protects you from malaria but not from sickle cell. Like with TRIM5a if you modify it you get protected from PtERV but not from HIV. You are never safe from both.

In all, viruses go beyond being malignant and infecting a host cell. Not all viruses solely function is to replicate nonstop in its host in order to perpetuate itself. There are endogenous viruses that have helped in the evolution of humanity. These viruses can be labeled as an “unseen hero.” Due to this, I say science should revive dead viruses. Although there may be ethical complications with the process, if it to help create vaccines against pandemics, the pros outweigh the cons.

This entry was posted in AP Biology, Evolution, Viruses. Bookmark the permalink.

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