Viruses are as much a part of the biosphere as are humans, grasshoppers, earthworms, and fungi. Viruses do exactly as viruses were evolved to do so well. Viruses appear to be as old as the oldest life on the Earth and we all have many thousands of them in our bodies. Every individual of all animal and plant species have many, many viruses in them. Some geneticists theorize that the vast proportion of DNA in our bodies that is not active at all in the development and maintenance of the body (well over 50% in humans) are ancient, harmless viruses that have found a very successful critter to tag along with – us! Most do no harm. They are commensal organisms – gaining benefit from association with us, but doing us no harm. After all, a really successful parasite will not kill its host before its host has reproduced – for obvious reasons. Other geneticists theorize that the aging process is the expression of lots of slightly harmful effects of all these accumulated stray pieces of DNA (all of which were/are potentially viruses). Taking this idea one step further, others have suggested that humans, ocelots, pigeons, kudos, crickets, violets, and every other successful form of life on Earth are just the shells or vessels that genes cooperate to build in order to propagate themselves into the next generation – not with intent, simply by the numbers. Those that operate better, end up leaving more copies of themselves — in the vessel operative association that worked so well to get them there. In this sense, genes are no different than viruses.
To the comment that viruses have “…destroyed millions of people, before the industrialization, they killed in the Middle Ages as well! It seems as if they are a part of Nature…” – Have not humans destroyed millions of people, before, during, and after industrialization? Did they not kill in the Middle Ages as well? For that matter, have not ocelots killed prey, pigeons killed seeds, kudos killed grasses, and crickets killed herbs ever since they made their debut? We are all “a part of Nature,” like it or not.
NOTE: At the request of Daniel Quinn, this question was answered by Dr. Alan Thornhill.
DATE: 20 Apr 1997
UPDATE: 02 Jun 2001