If you were to approach a random pedestrian and inform him that viruses have played a major role in shaping him into the person he is today, you would most likely be scoffed at and labeled insane. That is because the word “virus” carries a very negative connotation. Viruses make us sick, and no one likes to be sick. To most, it is as simple as that. However, in the article “Darwin’s Surprise”, Michael Specter offers a very counterintuitive explanation for human evolution. In the article, we learn that viruses have been a driving force behind our evolution.
One of the biggest biggest discoveries linking viruses and human evolution together came in the form of retroviruses. “Endogenous retroviruses are two things at once: genes and viruses” (3). This discovery is fascinating in the fact that these viruses can be inherited into our genome. Most diseases are only present in the infected person. Endogenous retroviruses, by virtue of being incorporated into our genome, can be passed down from generation to generation. Furthermore, there is much evidence present to suggest that “without endogenous retroviruses mammals might have never developed a placenta” (3). The development of the placenta has directly lead to live birth, which allowed us to develop larger brains and become more versatile. “The protein syncytin, which causes the placental cells to fuse together, employs the exact same mechanism that enables retroviruses to latch onto the cells they infect” (5). This particular sentence completely revolutions my approach to viruses. Contrasting something that seems so negative with the beginning of life provided me with a new outlook on viruses. I never knew that viruses were partly responsible for live birth, and have gained a newfound appreciation for them after learning this.
Another interesting idea that the article brings up about viruses and evolution is the difference in the AIDS virus between humans and chimpanzees. Chimpanzees are our closest relatives, therefore Darwin would have most likely argued that we should react similarily, if not identically, to the AIDS virus. That could not be further from the truth. “Chimpanzees are infected by the AIDS virus, but it never makes them sick” (7), and the only convincing reason for this is that “chimps have roughly a hundred and thirty copies of a virus called Pan troglodytes endogenous retrovirus (PtERV)…humans have none” (7). Initially, this seems like a good thing. Humans have evolved protection from this virus, and one less virus means one less thing to worry about. Sadly, this is a lot more complicated than it appears to be on the surface. Ironically, the same “evolutionary process that protects us from PtERV may be the central reason we are vulnerable to H.I.V” (7). This is because humans have a gene called TRIM5a that offers practically foolproof protection from PtERV. Rhesus monkeys have the same gene, however in them it offers protection from H.I.V. Therefore, all scientists have to do it figure out what causes TRIM5a to change its function, and the come up with an effective vaccine that would be accepted by the human body. Although this sounds fairly practical, it will most likely take decades to achieve this goal. However, due to recent advances in biotechnology and virology, this idea is entirely believable. Scientists are able to look at strands of DNA, find evidence of ancient viruses, and then reconstruct them in the lab, and have done so multiple times (i.e. Phoenix virus). Therefore, the idea of finding a way to enhance the function of our TRIM5a based on monkeys is not so far-fetching.
This article has entirely revolutionized my outlook on viruses. I, too, was one of those that, upon hearing the word, turned and walked in the other direction in order to avoid getting sick. I am not saying that I will not try and get sick, but I most definitely have a newfound appreciation for what viruses have done for humans. The fact that such a simple, non-living parasite has determined so much about our present day selves is mind blowing. Hopefully, with even more research done in this field, we will be able to learn more about viruses so that we can employ the information and use it to battle current epidemics.