Final answer:
The devolution or regressive hypothesis suggests that viruses may have originated from free-living cells, while the escapist hypothesis proposes they came from escaped genetic material from a host cell, and a third mentions a self-replicating system. Scientists study virus molecular systematics to gain further insight into virus origins.
Step-by-step explanation:
Determining the origins of viruses is challenging. The devolution or the regressive hypothesis proposes to explain the origin of viruses by suggesting that viruses evolved from free-living cells. This is one of several hypotheses aimed at demystifying the evolutionary background of viruses. For instance, the escapist hypothesis, also known as the progressive hypothesis, suggests that viruses originated from RNA and DNA molecules that escaped from a host cell. Additionally, a third hypothesis presents the idea of a system of self-replication, implying that viruses could have developed alongside host cells, evolving from self-replicating molecules resemble that those present in some plant pathogens.
Constructing a definitive origin story for viruses is complicated and continuously evolving with new scientific discoveries. Advances in the field, such as in virus molecular systematics, facilitate a better understanding of these mysterious entities by analyzing their genetic material, offering insights that could lead to innovative treatments for viral diseases.