what is alive?

Steve McGrew stevem at comtch.iea.com
Wed Sep 18 08:32:58 EST 1996


In article <m0v1SGm-0004N3C at uctmail2.uct.ac.za>, ed at molbiol.uct.ac.za wrote:

>For me, it's simple: it's not replicating; like fire, it is simply 
>propagating a chemical reaction which varies according to its 
>substrate; therefore, it is not alive.

        I've come in late to this thread, so I apologize if this is 
redundant--
        Wouldn't it make sense to consider "living" to be a matter of degree?  
For example, a dried lotus seed or a frozen spore *must* be considered to be 
alive to some degree, since it has the capacity for doing all the things 
living things do.  A person in a coma is less alive than one who is engaged in 
a lively conversation.  A virus is perhaps less alive than a eukaryotic 
organism, which in turn may be less alive than a dog.  And, a cancer cell is 
certainly alive, but perhaps to a lesser degree than the organism whose stem 
cells it arose from.
        Certainly we could cook up a definition for "life" that would provide 
a basis for calculating the "degree of aliveness" of a system, so that each 
animal, plant, virus, autonomous robot and river system can be allocated its 
own aliveness.
        I think a lot of the problem people have with the concept of "what is 
alive" may come from the idea that there is a "spirit" that enters leaves the 
body upon birth and leaves upon death: an on/off kind of quantity called 
"life".  In the context of current medical, biological, biochemical and 
cybernetic knowledge, that idea is nonsense.  If "life" is to be something 
science deals with, it must be measurable, quantifiable-- and probably not a 
binary quantity.

Steve 

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