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Thus a first temporality associated with viruses is that the field itself has formed and changed rapidly, much like the organisms that it studies. This is an unsurprising echo, as the fact that the viruses transgress spatial boundaries and mutate extremely rapidly has contributed to the change. |
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So what is the problem with correlating virus time with laboratory time? The overwhelming difficulty has been that it is extremely difficult for viruses to produce the kind of genetic classification whose genealogy Patrick Tort (1989) has so brilliantly traced across the social and natural sciences of the nineteenth century. A genetic classification is one that classifies things according to their originsrocks might be metamorphic or sedimentary, say; languages might be Indo-European or Nilotic. Viruses have multiple possible origins, they look and feel the same since they pass the filter test and make you sick, but they got that way along multiple paths (compare Alder 1998). This is an old problem in medical philosophy and diagnosisa cure does not necessarily reflect a cause, and there may be many paths to a single symptom or cure (King 1982). |
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Ward gives four theories for viral origins. First, it is possible that some viruses "evolved from autonomous, self-replicating host cell molecules such as plasmids or transposons by acquiring appropriate genes that code for packaging proteins" (Ward 1993, 433). In this picture they are simple chemical combinations that have acquired the replication habit of their material substrate. Second, "some viruses arose by degeneration from primitive cells in a manner similar to that proposed for the evolution of cellular organelles such as mitochondria and chloroplasts from bacteria" (Ward 1993, 434). Here they are complex organisms that devolved. Third, "some RNA viruses are descendants of prebiotic RNA polymers" (Ward 1993, 433). According to this theory, viruses might have coevolved with life itself. Finally, there is the possibility that ''some viruses evolved from viroids or virusoids, although it is equally possible that these small RNA, rather than being progenitors of viruses, are recent degenerative products of the more complex self-replicating systems." (Ward 1993, 434) Where you do not have a single origin story, you cannot have a single biological classification system. Viruses have been classed into families and then into increasingly controversial supervenient categories (only one orderthe mononegaviraleshas been approved to date by the ICTV). The supervenient categories frequently have the inconvenience of separating viruses that had been considered grouped together. |
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