When Enemies Make Us Human

I don’t think Darwin would be tossing and turning in his grave, but he certainly would be in for a shocking revelation on how humans and different species have evolved through viruses. Darwin came up with his theory to evolution without the knowledge of genes and genetic material, so first and foremost, that would certainly surprise him. Not only that, but what would surprise him the most would be that viruses, the very things that get us sick, would help us to adapt and evolve. Darwin’s idea of natural selection suggests that organisms who were sick would die out and those with resistances would be selected for. However, Darwin’s Surprise brings into light the idea that the viruses that can impact our genomes, retroviruses, would have modified us as organisms. Darwin would be surprised to see that instead of a population adapting to a disease, the disease has made adaptations and mutations to the population.

I find it fascinating that viruses can become endogenous, and I was most surprised that infectious viruses like HIV (belonging to a class called “lentiviruses”) could become embedded in our genome as well. Personally, I find it a bit scary that a virus that I have caught or have been infected with could impact the genes of future offspring. The article mentioned that these segments of DNA from viruses could still code for proteins. Even though many of them do not produce viable proteins that work, it still makes me think that when a virus implants its DNA, it could create an organism with peculiar qualities. For instance, I imagine that the first organisms to have live births were thought of as being quite odd compared to their egg-bearing counterparts. Granted, the odds of a virus becoming endogenous is very very rare, but it still is frightening to know that something caught in your lifetime could have slight or very deep impacts on your posterity.

Darwin’s Surprise suggests that without retroviruses, the human species and other species as well would not be where they are today. For example, the use of endogenous retroviruses could have let mammals to have a placenta, allowing for the development of a larger brain and a longer development period. This DNA is often called “junk DNA”, however as Robin Weiss suggested, the DNA was not “junk” or merely harmless, but rather had a function in terms of the creation of a placenta. We learned in class as well that the “junk DNA” proves to be beneficial in terms of lengthening the DNA strand  and allowing the non-coding parts to get cut at the ends to conserve the coding regions. As the article stated, we are playing a game of “cat and mouse” with viruses and our own survival, and I believe that we have definitely caused each other to evolve and have evolved together. While I still dislike viruses for a variety of different reasons (I’m not going to be ecstatic if I get infected with a retrovirus like HIV or even a virus like the flu), I can come to be a little more understanding and accepting of viruses. Instead of being 100% evil, I’ve come to see that our relationship with viruses is a complex one and that it can’t be defined as simply good or bad, but rather a combination of the two.

What startled me that most about the article was that scientists had the ability to take these bits and pieces of retrovirus genetic material and piece them back together. I was torn between finding it fascinating but also horrifying. Personally, I would not like a thousands-of-year-old virus to go about infecting the population again just like how even though I would love to see a dinosaur in real life, I definitely would prefer to not have them resurrected at full potential. I think that if there is a legitimate reason for resurrecting prehistoric viruses, for instance to understand a retrovirus like HIV better, then bringing old viruses back to life can open doors to our knowledge of how they work. However, in cases where resurrection is done simply just for resurrection (example: creating a polio virus just to “prove it can be done”), I believe it would be best to spend time and money researching other things.

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2 Responses to When Enemies Make Us Human

  1. MaryH says:

    I feel like viruses have always had a bad rep, for very good reasons too. Especially considering the growing rates of HIV/AIDS within the last few decades, it’s very easy to see why viruses could be considered, “the single biggest threat to man’s continued dominance on this planet,” as Joshua Ledenberg put it. So I also found it shocking that the incorporation of viral DNA into our genome likely has actually significantly contributed to us becoming human. In class we discussed the potential origins of introns in endogenous viral DNA and I had the same reaction. What could have been thought of as just “junk” may actually be a link to our evolutionary past. And the reconstruction of our evolutionary past and the lineages of other organisms does have the potential to produce some very interesting and maybe wacky results. The fact that organisms share genetic traits is indicative of a universal common ancestor, central to Darwin’s theory of descent with modification. But, like you mentioned, Darwin had no knowledge of genetics; that would be the first surprise. And the fact that endogenous viruses, which cannot even be considered living, have played a role in evolution would be the second. And it’s not only a surprise to Darwin, but to biologists and researchers everywhere, some of whom have shifted focus towards reconstructing extinct viruses. I agree that this practice of reconstructing viruses should not be the Jurassic Park method of proving it can be done. But in the right hands, the potential of these non-living evolution machines could link us to the discovery of a past we never knew and a deeper understanding of evolutionary biology.

  2. McKenzieL says:

    I see your point that we can’t be resurrecting millennia-old viruses just for fun, because that would almost surely give rise to a film franchise that steadily declines in quality. All jokes aside, I think experimentation with resurrection is unavoidable. Humans are naturally curious; we never know when to leave something alone. Now that we’ve cracked the door open on recreating extinct viruses using the introns of animals, there is no doubt in my mind that the door will be pushed open so far it barely clings to its hinges. Science is a double-edged sword, and there is no way people will stop testing the limits of what they can and can’t do. This notion is terrifying, but I believe it is inevitable. Maybe one day we’ll have a theme park with millions of animals infected with formerly extinct viruses, because that seems like exactly the kind of ridiculous thing advances in molecular biology could end up being used for.

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