The Origin of Viruses and The Evolution

By Sung Joo Chun '22

The evolution of Viruses has been a controversial and inconclusive topic for cell biologists. The diversity of the viruses had made it hard for scientists to classify the entities and features and related them to the conventional tree of living organisms and life. Viruses are in fact alive and are able to carry out metabolic processes along with the ability to grow, reproduce, and evolve. Then, what did these viruses originate from?

The origin of viruses is supported by two hypotheses. The first hypothesis is the progressive hypothesis. Viruses with a single-stranded RNA genome, which are called retroviruses, convert their single-stranded RNA into a double-stranded RNA once it enters its host. The viral genes enable the virus to duplicate itself in the host’s body allowing it to infect and control the host’s body and other cells as well. The RNA polymerase comes into aid for this process. Once the host is infected, the progeny virus exits the body to start the process all over again on another host.

The second hypothesis is the regressive hypothesis. This theory states that bacteria and viruses may have originated from complex eukaryotic organisms and have gradually lost their complexity and genetic information and reached their parasitic approach.

Both the progressive and regressive hypotheses support the fact that cells existed before the viruses did. Researchers speculate that viruses were one of the first entities that we're able to duplicate themselves. As time progressed, they became more organized and complex with enzymes that allowed the synthesis of membranes and the evolution of cell walls. This explains the evolution of viruses and bacterial cells.