Darwin did not know about DNA and genetics, or how genes were passed down from generation to generation and selected for. To have our evolution be so driven by viruses embedded in our DNA would have sounded crazy to him. These viruses, in particular retroviruses, have provided yet another tool to investigate ancestral relationships between animals, besides the homologous structures Darwin studied. In fact, Darwin would have expected that organisms that were infected by these viruses would be selected against in nature, as they were less fit, and so died early, meaning they had a lesser chance to reproduce.
I thought that the concept of viruses, specifically retroviruses, playing a beneficial role in an organism’s life was surprising. Reading that retroviruses made it possible for mammals to develop placentas and therefore develop a direct line of nutrition from mother to offspring, and therefore allowing the offspring to develop larger brains was a surprise for me. The idea of the genetic material of harmful viruses incorporating itself into an organism’s genome seems fantastical, even paradoxical. However paradoxical, the remains of these retroviruses make up 8% of our DNA. This incorporation eliminates the threat of retroviruses in organisms, a very different process from an organism’s regular defense, in which harmful molecules are broken down or inhibited. However, this allows the immunity to retroviruses to be passed down to successive generations.
The article suggests that the pieces of retroviruses found in the DNA of an organism play a significant role in its evolution. An example of this is the development of the placenta, as I mentioned before. Although retroviruses may seem to pose a health risk to the mother and offspring, it was found that mechanisms in the retroviruses actually mirrored those of proteins found in placental cells, which allowed them to fuse together to form a placenta. This information caused me to change my opinions and understanding of viruses. When, before, I viewed them as simply harmful, I now see that retroviruses play a significant role in our own evolution. The study of retroviruses is even indicating some potential treatments to viral diseases like HIV that we can possibly eradicate it in the future.
While I definitely did not think so before reading the article, I see now that there is an advantage to reviving dead viruses for scientific purposes. If scientists can use their records of extinct viruses to recreate and observe them, they can gain new perspectives on how to eliminate them. While resurrecting dead things sounds like something from a science fiction movie, the knowledge gained would prove invaluable to future organisms’ survival. Studying these retroviruses would allow scientists to pinpoint the processes that caused many of them to become extinct, so that we replicate the process.