Darwin’s Surprise

Darwin might find it surprising that the organism most at arms with humans, the most advanced species on the planet, are the lifeless viruses, the simplest carriers of genetic information. Darwin’s surprise is that endogenic retroviruses such as H.I.V. could very well be the strongest driving force behind evolution. For example, Heidmann and others suggest endogenic retroviruses play a role in characterizing mammals against other animals by fueling the development of the placenta (Specter). It is because of these advances that viruses can be thought of as “a major creative force” in our evolution (Villarreal). Viruses evolve along with us, as we are able to synthesize modified proteins that are not complimentary to the virus’s receptors, the virus finds ways to modify their receptors. Descent with modification absolutely applies to the infectors and the ones infected.

I found the mere fact that endogenic retroviruses consist of about 10% of our genome very surprising. It makes sense that viruses will have embedded their own DNA into ours if they are passed along the gametic germ cells. The concept that viruses can prove advantageous also makes sense as imbedded viruses would help us recognize and fight against new strains of similar viruses. It astounds me that the best possible way to find cures to the current most deadly viruses such as H.I.V. is to resurrect past endogenic retroviruses. Also, I find it interesting that the presence of an endogenic retrovirus can be something that divides two species, such as the human and the chimpanzee, apart.

The presence of viruses such as PtERV in the genomes of chimpanzees and gorillas help to explain why H.I.V. does not cause them harm. Being similar to H.I.V., PtERV allows these apes to recognize H.I.V., and prevent it from being lethal. Examining this evolutionary history gives us insight to our own genomes, and explains why H.I.V. is one of the biggest threats to us, but not to our closest relatives. When we diverged from our common ancestor with the chimpanzee, we could have either never been infected with PtERV, or those who were all died. We can look to endogenic retroviruses much like the fossil record, finding many commonalities among related organisms and the viruses in their genomes. In another example, the recently introduced koalas are susceptible to a virus that the southern island koalas are not. This gives scientists a great opportunity to witness evolution in action. This article has definitely turned my understanding of viruses upside down. I never could have imagined that viruses could increase fitness, and that they are such important parts of making a species distinct.

Such as with the benefits derived from stem cell research, I would absolutely be supportive of paleovirology and the practice of looking at the mechanisms of past viruses to help us understand and find cures for current ones. Scientists such as Heidmann and Malik are doing work to advance our species’ fitness. As Heidmann stated, “the phoenix virus sheds light on how H.I.V. operates, but, more than that, on how we operate, and how we evolved.” Doing this sort of research would kill two birds in one stone. We would not only be able to find cures to viral diseases faster, but also we would be able to better understand our history. 

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5 Responses to Darwin’s Surprise

  1. jamesfan1 says:

    The development of paleovirology and subsequent advances and discoveries made, such as the existence of PtERV in both the human and closely related species such as the chimpanzee and the gorilla, indicates that this field has great promise in the near future. The breakthroughs that could occur would have huge effects on the treatment of previously incurable diseases such as HIV infections. Specifically, the study of PtERV and the resistance that chimpanzees and gorillas have to HIV could reveal how earlier humans became resistant to the cause of PtERV and link that to the current situation with HIV. While the article stresses the fact that this discovery will not occur in the foreseeable future, it is still heartening to see steps being made to a final therapy that could prove effective in completely stopping HIV.

    In addition to research into preventing human diseases, paleovirology could also provide new methods of observing the evolutionary cycle of infections and defense mechanisms combating those infections. As the post notes, the studies on koalas that were sequestered on a separate island and reintroduced could provide insights on how retroviruses become endogenous and what implications that might have. With these opportunities, paleovirology may be able to discover complex explanations to why and how endogenous retroviruses are found in the human genome, contributions that makes a human, well, human.

  2. TasqinZ says:

    I agree that Darwin would find endogenic viruses the strongest driving force behind evolution but I also believe that he would be surprised to learn that viruses help support his claim that humans and apes share a common ancestor. These viruses help support his argument because humans share most of their viral fragments with chimpanzees in the exact same place in our genome. It would be virtually impossible for us to aggregate the same virus fragments in the same location in our genes individually of each other. Hence, the only possible explanation is that we share a common ancestor from whom we inherited these endogenous virus fragments.
    It was also interesting to learn how viruses can help humans. As stated in this response, the placenta was a virus that helps distinguish mammals from other animals by allowing us to develop and mature—a advantage that being nurtured in an egg does not provide. I was also surprised to learn that the same method of viruses attaching to cells to infect it is used by the placenta to fuse its cell together: “In fact, the protein syncytin, which causes placental cells to fuse together, employs the exact same mechanism that enables retroviruses to latch on to the cells they infect.” This changed how I always thought that viruses can only result in a harmful effect on the host and instead made me think about whether we can use the behavior of a virus to benefit humans by the use of technology and the information we do have about viruses.

  3. NoraB says:

    I also though it was very interesting that the presence of a retrovirus could cause a huge divide in species, or even help them perpetuate. I think it is very possible that through resurrecting retroviruses we could learn how to cure HIV, or at least prevent it more effectively. This article did make me wonder about the effects current retroviruses have on our DNA today. You mentioned the koalas, I wonder if the same thing is happening with humans.

  4. PaulineE says:

    I thought this response was great! I definitely agree with a lot of the components that were found surprising here. To build upon them, an interesting disparity that I noticed was between the resurrection of viruses that you mentioned, and our knowledge about how they actually evolve. The article mentions that “nobody knows” what transforms an “infectious virus…into one that is inherited”. It also states that because the current trend of resurrecting retroviruses uses information from our DNA, we only have access to information about “viruses that made it into the germ line”. This illustrates a noteworthy gap between the rhetoric of these scientists, who are claiming techniques like resurrection are the best, almost sure-fire, way to find answers, while the amount of information they actually have about viruses is fairly limited. Further proving this is that that these viruses being resurrected are not in the majority. In the article, Bieniasz, a professor of Virology, notes that the majority of viruses are those that do not get into the germ line. That said, this technique still seems to be a good starting point—your examples about PtERV provide a good demonstration of that. Additionally, if our concern is about our evolution and viruses, learning about viruses that do become parts of our DNA seems crucial because this allows us to inherit their information, and thus their effects become a part of the body’s response to its surroundings for generations.

  5. kniedzwiadek says:

    I enjoyed reading your post, and I am especially interested in replying to some of the things you found interesting about the article. While I understand what you mean by, “It astounds me that the best possible way to find cures to the current most deadly viruses such as H.I.V. is to resurrect past endogenic retroviruses”, I think it is important to note that there usually is no sure way of knowing if something is the “best possible way” of accomplishing anything, especially if that something is as complex as treating HIV. Many scientists studying these viruses have very different, and sometimes even opposite, approaches to developing an effective treatment for HIV. For example, one treatment that the article mentions involves speeding up the life cycle of the virus in order to accelerate the virus’s already rapid pace of mutation to the point where it produces such an enourmous number of errors in its genome that it ceases to pose a threat. Other treatments involve taking the exact opposite approach and using various drugs to interfere with the virus’s ability to reproduce itself. Both treatments have potential and are effective to a certain extent, but neither has proved to be the best possible treatment. It just goes to show that we have much more to learn about endogenous viruses, and hopefully in the future we will be able to find more effective treatment methods.

    I also think it is interesting that “the presence of an endogenic retrovirus can be something that divides two species, such as the human and the chimpanzee, apart”. This idea was very surprising to me as well because it suggests that endogenous retroviruses have shaped our evolution into the species we are today. This makes me wonder if there are other factors we have never even considered that have played a significant role in our evolution…

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