Miller and Urey Experiment: What has changed?

Not all scientists agree with Dr. Racaniello. Do you even know who he is?

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The simplest answer is: "That depends".1 This is not meant to be flippant but it recognises that much of the definition of a word like "life" comes from personal perspective. There is no real wrong or right. You make your case for why you think it is or is not alive, and that's your posiiton. Cool. At best, viruses could be considered undead. No zombie parallels please-they don't eat brains

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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 categorization of viruses as nonliving during much of the modern era of biological science has had an unintended consequence: it has led most researchers to ignore viruses in the study of evolution. Finally, however, scientists are beginning to appreciate viruses as fundamental players in the history of life.

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Viruses are infectious particles that consist of a DNA or an RNA molecule (the viral genome) packaged in a protein capsid, a protective coat that allows their transfer from one cell to another. Although it is in our nature as humans to try to classify things in order to make sense of the world around us, viruses may exhibit characteristics of both living and non-living creatures depending on the definition of life used. According to Schwann and Schleiden’s cell theory dating back to 1839, all living creatures are made of individual units of life called cells — small membrane-bounded compartments filled with a concentrated aqueous solution of chemicals. The simplest life forms are unicellular organisms; higher organisms, such as ourselves, are like cellular cities in which specialized functions are performed by different groups of cells linked by intricate communication systems. Under this definition, viruses are acellular particles and thus are definitely not alive. If one’s definition of life is a more evolutionary one, with an organism being defined as the unit element of a continuous lineage with an individual evolutionary history (Luria et al., 1978), then viruses are definitely alive.

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SourceScience is not all black and white. Few things are. Life, as science has shown, has a lot of grey.Oh others can argue by link too. Not much fun is it.ABE
Oops sorry I see NoNukes beat me on this.Edited by Theodoric, : No reason given.