In a discussion about the definition of immortality Oliver Bogler wrote:
>> But to me that is no different from saying that the stem cell that divides
> at age 120 is immortal because by definition it is derived from a cell
> that was onboard at birth. You only get cells from other cells - they are
> not ever made de novo. So the experiment would be to see whether there are
> any dividing stem cells at age 120 - and that is all.
I have serious difficulty with this definition. We do not know how long an
individual stem cell lives. The parent cell may divide and then fully
differentiate, i.e. until death. The daughter cell does the same, etc. Each
individual cell may live for a few days only. Yet you call the cell immortal.
In this definition a cell is immortal when its descendants keep multiplying.
As someone else has said, this would imply, logically, that the only immortal
cell was the first one.
Bacteria, which will go on multiplying when regularly placed on a new
substrate, would in this line of thinking also be called immortal, although
we know for a fact that each cell only lives for a day or two.
Also human beings would then be immortal, since they have ever been multiplying
(with some success). This shows that the definition defies common sense.
I could agree with calling a cell culture immortal, but there is some hybris in
the word. Isn't it a bit exaggerated? How could we prove it? Things that
cannot be proven or disproven are outside the realm of science. The term,
therefore, is unscientific.
Wouter van Doorn
ATO-DLO, Wageningen, Holland
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