The economy of RNA life

HIV, flu and recently coronavirus have caused havoc to human societies. These viruses are all RNA viruses. Are RNA viruses very strong? On the contrary, they’re very weak. If so, how can they cause so much damage?

Many of us, as babies or parents of babies, have read Three Little Pigs. In that story, one little pig built a straw house, the second little pig built a stick house, the last little pig built a brick house. RNA viruses are the straw house. DNA organisms are the brick house. Our immune systems can destroy RNA viruses easily, just like a wolf can destroy a straw house easily. So why RNA viruses can cause so much trouble?

It is much easier to build a straw house than a brick house. It takes a lot of time, effort and especially cost to build a brick house. When the last little pig struggled to build his brick house, the first little pig had already settled down in his straw house, raising many young piglets with his wife. Those piglets in turn build many new straw houses and raise many new babies. 

RNA viruses are the same. Comparing with DNA life, RNA viruses are very cheap to make. So RNA viruses can multiply very quickly in our bodies, although most of them are quickly destroyed by our immune systems.

Brick houses need some design standards. The shapes of doors, windows have to follow specific designs. Straw houses, on the other hand, are much more flexible. There is really no need for a building code for straw houses. Similarly, the structures of RNA viruses are are more flexible than more complex DNA life. RNA viruses are very unstable and mutate very fast. This makes it much harder for immune systems to develop specialized antibodies to efficiently eliminate RNA viruses. 

Many people expect the arrival of vaccines will eliminate coronavirus soon. However, the record of developing vaccines against RNA viruses is mixed. We have not been able to develop HIV vaccine, despite tremendous efforts. Flu vaccines are not very effective, because flu viruses, as RNA viruses, mutate very fast. DNA pathogens, such as smallpox viruses, are more stable. It is easier to develop vaccines against DNA pathogens in general. So we might not be able to find effective vaccines against coronavirus soon.

RNA viruses can mutate very fast. It is very easy for RNA viruses inhabiting non human hosts to acquire segments of viruses that inhabiting human hosts. It is relatively easy for RNA viruses to evolve the ability to inhabit human hosts. Even if vaccines against novel coronavirus turns out to be successful, new RNA viruses may emerge to host human species. RNA viruses can jump from species to species easily. We will face constant threat of new RNA virus pandemic, giving the high density and high mobility of human population.

So are we hopeless in dealing with RNA viruses? If RNA viruses are so successful, maybe we can learn something from them. The key of RNA viruses’ success is their low cost and simplicity. Our modern society is too expensive to maintain. As a result, our families couldn’t afford to have two children on average. With less and less young people, our population ages. This makes our society very vulnerable to any disturbances. 

In fact, we don’t need to look into RNA viruses for insight. Many societies have much higher fertility rates and much younger populations than the western societies. But because of their simple social structures, we often patronize them. Very often, those could not afford a single child rush to help those having seven or eight children. Some couldn’t see the simple fact that a society with above replacement fertility rate is more youthful, more energetic and more dynamic than a society with below replacement fertility rate.

We demand heavier and heavier armor to protect our aging society. But the heavy armor only wears us down. When the nimble viruses break through our containment, we are utterly exposed and helpless. To revive our aging society, we have to abandon the heavy and restrictive armor. We need to reduce our burden. We need to light ourselves up. We need to rejuvenate our society with more babies and juveniles.

RNA life are more ancient than DNA life. RNA life are simple, agile and versatile.  RNA viruses have weathered all attempts to eliminate them by large and complex  DNA life. The complex and clumsy machineries of human society will never eliminate the eternally young RNA life.  We have to be humble, to live with them, to accept discipline from them and to learn from them.