Non-cellular Life - Controversy

Controversy

The initial interest in viruses stemmed from their association with diseases —the word "virus" has its roots in the Latin term for "poison." Their demotion to inert chemicals came after 1935, when Wendell M. Stanley and his colleagues, at what is now the Rockefeller University in New York City, crystallized a virus— the tobacco mosaic virus— for the first time. They saw that it consisted of a package of complex biochemicals but it lacked essential systems necessary for metabolic functions, the biochemical activity of life. Stanley shared the 1946 Nobel Prize in chemistry —not in physiology or medicine— for this work.

Further research by Stanley and others established that a virus consists of nucleic acids (DNA or RNA) enclosed in a protein coat that may also shelter viral proteins involved in infection. By that description, a virus seems more like a chemistry set than an organism.

The seemingly simple question of whether or not viruses are alive, raises a fundamental issue: What exactly defines "life?" A precise scientific definition of life is an elusive thing. (See definition of life.) Although viruses challenge our concept of what "living" means, they are vital members of the web of life. Viruses have their own, ancient evolutionary history, dating to the very origin of cellular life. It has been recognized that viruses have played (and still play) a major innovative role in the evolution of cellular organisms. Most evolutionary biologists look on viruses as coming from host genes that somehow escaped the host and acquired a protein coat. In this view, viruses are fugitive host genes that have degenerated into parasites. But by viewing viruses as inanimate, these investigators place them in the same category of environmental influences.