The Origins of Viruses
There currently are three main hypotheses explaining the origins of viruses. The virus-first hypothesis states that viruses have originated before the cellular lifeforms. It is usually rejected because all viruses seen today require a cellular organism to replicate. The second hypothesis says that viruses have resulted from reduction of cellular organisms. It is also usually rejected because parasites produced from various cells keep their cellular characteristics. The third hypothesis, the escape theory, states that viruses are parts of genetic material that escaped from the mother cell and became parasitic. It is the most widely supported hypothesis today, though it is still hard to explain how those parts of genetic material could develop other complex mechanisms that can be seen in viruses today.
The major problem with these theories is that they are trying to explain the origins of a very ancient organism using only present-day observations. If we assume that ancient cells were simpler than modern ones, we could look at the theories from a new perspective. The virus-first hypothesis becomes more plausible if at first there were just molecules competing with each other. It also becomes easier to explain the escape theory, since viruses formed from genetic material predating LUCA. However, I think that the most plausible explanation is the reduction hypothesis. In the early world of RNA cells, some cells were able to develop useful traits, making it difficult for other cells to survive without becoming parasites. This theory explains how viruses have their structures, why they invade other cells and why they have distinct features that are not seen in modern cellular organisms. The escape and virus-first hypotheses create a lot of speculation when trying to explain how free genetic material could acquire other components. The reduction hypothesis is simple in its explanation and is consistent with the way evolution and natural selection …
