Darwin’s Surprise – Response

I think this article is titled Darwin’s Surprise because the viral component of our evolution as humans would surprise him. Though Darwin believed our lineage could be traced through common ancestors, he would be surprised to know how large of a role viruses might also have played in driving our evolution. Retroviruses in particular have provided another tool with which to investigate relationships among animals. In addition, Darwin would expect that organisms infected by a harmful virus would be selected against by nature because they were less fit to survive and reproduce. It would seem counterintuitive that retroviruses have made their way in pieces into our DNA.

I found the concept of retroviruses becoming part of an organism’s genome and making it  resistant to the virus to be surprising. The idea that incorporating the genetic material of something that can be so devastating into an organism’s genome could be beneficial seems contradictory. I was very surprised to find that eight percent of our DNA is composed of the remains of retroviruses. So much of an organism’s defense against harm seems to be preventative, whether is be breaking down the intruder or  inhibiting its processes. However for the retroviruses, it is their incorporation that eliminates them as a threat. That immunity can then be passed on through the generations.

The article suggests that viruses play an extremely significant role in evolution. If pieces of retrovirus DNA have ended up in our DNA, the article claims they must have played a “major role in our evolution.” One of the specific cases pointed to is the development of the placenta. Scientists found retroviruses on the syncytium of the placenta in many different mammals. Despite the presence of the retroviruses, all the organisms were healthy. Mechanisms in the retroviruses were mirrored in the placental cells by the protein syncytin which allows the cells to fuse together. The information and ideas presented in the article definitely changed my understanding of viruses. It is easy to look at them as purely harmful, what with all the damage they have and are still causing. Their mechanics are fascinating, but they achieve such terrible ends. However it appears that not only have they played a massive role in our evolution, but the study of viruses is opening doors to new potential solutions to the worst viral diseases. They have proven to be capable of much more than just inflicting damage to organisms and have possibly had crucial effects on humans that allow us to thrive.

I think there is definitely an advantage to being able to revive dead viruses for scientific purposes. Scientists have the records of many extinct viruses existences. If they can recreate and observe them, they could lend a very unique and helpful perspective to how to eliminate current viruses. It is a frightening concept in a way, but if the knowledge is used for the right purposes it could prove invaluable. Especially since many extinct viruses were defeated by the organism they used to invade, studying them further will likely allow scientists to zero in on the exact processes that allowed the organism to accomplish such a task.

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3 Responses to Darwin’s Surprise – Response

  1. ZeenaF says:

    You bring up a very good point about how easy it is to assume that all retroviruses as “purely harmful,” when really they play such an important role in our evolution. Beyond the example you gave of helping mammals develop the placenta – which enabled us to have live birth, which is a huge evolutionary step – the article also mentioned how a retrovirus possibly extremely similar to HIV is what created the difference between humans and chimpanzees. Despite how similar humans and chimpanzees are, I think we can all agree that there is still a gargantuan difference between the two species. What figuratively blew my mind while reading this article was that statement. Imagine, after the HIV virus runs its course, there may be an entirely new species similar to humans and chimpanzees yet altogether different. Woah.

  2. sasvoboda says:

    Darwin may be surprised at first to hear that any kind of virus is actually a part of our human genome, but I believe that he would be supportive of the idea that we evolved down the path that we did as a result of our interactions and relationships with viruses. As we were able to develop a response to a certain endogenous retrovirus, neutralizing it, we were able to survive to maturity and reproduce. We were able to pass the endogenous retrovirus gene to our offspring. I also think that Darwin would be surprised (at first) by the fact that Koronis Pharmaceuticals hopes to, “accelerate the virus’s already rapid pace of mutation to the point where it reproduces such an enormous number of errors in its genome that it ceases to pose a threat.” Although Darwin was aware that variation was essential to the process of natural selection, it might initially be shocking to hear that there are theories suggesting that a virus may become extinct simply by letting it mutate rapidly enough that it doesn’t pose a threat to it’s host. Using variation to stop an organism from threatening other organisms– originally one of its most advantageous traits– may not at first seem advantageous for the virus mutating.In the second paragraph, the author states, “I found the concept of retroviruses become part of an organism’s genome and making it resistant to the virus to be surprising.” The incorporation of the retrovirus into the genome occurs simultaneously with the viruses mutation causing it to be harmless or, “extinct” (as Specter writes in the article) but the incorporation is not the reason for becoming harmless. It is the opposite. As the virus mutates to the point where when it can infect a germ-line cell without killing it (the virus is harmless to the cell), the offspring will survive and the genes containing the virus will be passed along from generation to generation.

  3. IsabellaC says:

    I agree that retrovirus incorporation in our DNA seems counterintuitive, but before reaching that point it I would also reference Darwin’s lack of knowledge as to DNA itself. I was also very surprised that retroviruses constituted so much of our DNA, but when I began to learn more about how they function it made sense that the key to protection lies in ancestral exposure. I think that explanation, and mentioning how this immunity can be passed on, was really well-incorporated. Referencing the placenta was also really effective in further exploring the meaning of incorporated retrovirus DNA. What you said about the implications of paleoviroligy really stuck with me- if we study the process of how organisms “defeated” different viruses, then we can use that information to overcome current and future viral attacks.

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