Are Viruses Alive?
Luis P Villarreal December 2004 Scientific American Vol. 291 Issue 6, p100
This article discusses how viruses, somewhere between living and nonliving, are categorized in biology, and their role in evolution. For about 100 years, the scientific community has repeatedly changed its collective mind over what viruses are. First seen as poisons, then as life-forms, then biological chemicals, viruses today are thought of as being in a gray area between living and nonliving: they cannot replicate on their own but can do so in truly living cells and can also affect the behavior of their hosts profoundly. The seemingly simple question of whether or not viruses are alive, which my students often ask, has probably defied a simple answer all these years because it raises a fundamental issue: What exactly defines "life?" Viruses have their own, ancient evolutionary history, dating to the very origin of cellular life. In fact, along with other researchers, Philip Bell of Macquarie University in Sydney, Australia, and I contend that the cell nucleus itself is of viral origin. INSETS: Overview/A Little Bit of Life; Rising from the Dead--and Other Tricks.