Virus. Just the very word brings out the worst connotation possible. People always see viruses as horrible little agents that bring out the worst diseases. However, reading “Darwin’s Surprise” may change the opinion of the public (to a reasonable extant, of course.)
To start off, the article is titled “Darwin’s Surprise” for a good reason. Charles Darwin was the man who first popularized the concept of evolution. He didn’t “invent” evolution, but he did point it out after studying finches on Galápagos Islands. Darwin’s theory of evolution connects all living beings together. Apart from the original problem of Darwin probably not knowing what a virus is (Dmitry Ivanovsky kind of started virology in 1892. Darwin went on his voyage in the 1830s), Darwin would have probably never suspected that viruses contributed to human evolution just because of their state as nonliving agents. The naturalist’s theory considers nature as the only true changing factor of evolution. However, this new theory would surprise Darwin as it adds in another factor that helps animals evolve: viruses.
But enough about the past. It’s time to think about now– what can these viruses do for us? Well, the article did point out many interesting facts. Although I would recommend the entire article to read, I managed to pinpoint a top three surprising things that the article brought up:
- Thanks to viruses we don’t lay eggs (page 3-4)
- The article almost immediately begins with something that changes basically everything that one may know about science. It’s a common fact that (most) mammals do not lay eggs. This is clearly advantageous as it’s perpetuated. But what does this have to do with viruses? Well, it turns out that thanks to retroviruses, mammals were able to create the placenta, which permits the mammal to protect its fetus. This allowed live birth to happen, which was a huge advantage as being in an egg doesn’t eliminate waste nor draw maternal nutrients required to have a large brain.
- Humans get infected with HIV but apes do not (page 6)
- Okay. This may not sound as surprising as one would expect. Without further analysis, this seems like a pretty common fact. However, “Darwin’s Surprise” further explains why this is so strange. Chimpanzees, human’s closest relatives, can be infected by HIV but don’t experience the same drastic symptoms that humans do. Scientists explored this and found that the biggest difference between their genome and ours is that chimps’ genome has over a hundred copies of the pan troglodytes endogenous retrovirus (PtERV). Gorillas, another close relative, have eight copies of this virus in their genome. Meanwhile humans have exactly zero. After finding this retrovirus, scientists began to believe that PtERV has an affect on HIV’s effects. Upon further inspection, scientists found that humanity’s TRIM5α produces a protein that destroys PtERV. So the scientists went a step further and modified TRIM5α so that it works like the chimp alternative, which means that the protein produced by TRIM5α no longer protected humans. Next, the scientist placed the new TRIM5α with HIV and then, in a different dish, with PtERV. The protein should have blocked HIV and PtERV, no? Wrong. The protein was able to protect the cell from either HIV or PtERV, but never from both.
- Speeding up HIV may help destroy it (page 8-9)
- This one may sound even crazier than the previous two, but it’s just as interesting. First, we should think about what allows prokaryotic species to change from generation to generation– cell reproduction. In germ line cells, meiosis helps create very different offsprings due to crossing over and random assortment and different alleles etc. However, somatic cells don’t have the same chance at changing per cellular reproduction. That’s where mutations come in. A mutation may be harmful, or helpful, or really insignificant– it all depends on the environment and the mutation itself (i.e. which nucleotide is affected, how many, what is the new translation, etc.) But what does this have to do with viruses? Well, viruses can experience mutations, just like our cells. And, just like with cells, the faster the virus reproduces, the more likely it is to make an error. Just like in cells, mutations may have dramatic affects on its function. Therefore, in viruses, the faster it reproduces the more mutations it has and hence it is more likely to be less dangerous to the host.
Although the article had many more surprising virus facts, these top three were the ones that I found the most interesting.
But what does this mean in terms of evolution? If viruses can create such grand changes as allowing live birth or preventing certain viruses from affecting the host, then they’re clearly an advantage (disclaimer: not ALL viruses are advantageous. It’s kind of like bacteria. Some bacteria, like lactobacillus, is good and is part of what makes us human. Some bacteria is detrimental, like streptococcus.) The article suggests that viruses have dramatically helped drive evolution. I agree with this: retroviral DNA is part of human DNA. Without it, humans wouldn’t have evolved to what they are today. Viruses are also very important when it comes to a species changing into two species. Such was the case with the common ancestor of humans and chimps: humans are protected against PtERV while chimps are protected against HIV because at some point there was a split with the function of TRIM5α. This article changed my view and understanding of viruses. Like practically everything else on this planet, viruses contribute to the changing world, the differences between generations of species until new species show up, the differences between beings that survive specific events and beings that don’t, etc.
But how bad is too bad? Well, this is entirely subjective. Scientists believe that viruses are interesting. In fact, they’re so interesting that it’s worth bringing back “dead” viruses. Should we “revive” them? For the sake of science, I believe that yes, we should revive them. As the article stated, by reviving dead viruses we can learn more about what makes us human. We can also learn more about combating harmful viruses, such as HIV. However, I still believe in moderation. I think that as long as the viruses are contained in secure laboratories and are used for research purposes only, then it should be fine. We could learn a lot, hopefully without taking advantage of such an opportunity.