On 04/08/2011 01:53 PM, Le_Forgeron wrote:
> It's even worse than that: each customer not only get a full different
> program, but installed it (with variations) on billions of computers
> (most cells get a full copy, initially).
>
> As cells divide, each copy mutates and get truncated or duplicated code.
> Statically, it's the same program... in theory. In practice, the
> survival is only based on the ability of the new program to still
> duplicate the cell.

As best as I can tell, mutations are actually very rare events. There 
are specific mechanisms which exist expressly to detect and correct such 
defects. That includes DNA repair mechanisms, automated destruction of 
misfolded proteins, and extracellular signals used to program mutated 
cells to shut down and die.

Cancer happens when these mechanisms fail to correct a mutation /and/ 
that mutation happens to be do to with growth processes. Observe that 
cancer is quite rare. (E.g., it's not like 50% of people get cancer or 
anything like that.)

So it's not like every single cell in your body has a completely 
different copy of your genome. Actually the differences are tiny, if 
existent at all. The major place where these mutations become 
significant is during reproduction, where the entire organism passes 
through a single genome copy. If /that/ gets changed, it's probably 
permanent.

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