In <01bdca73$e3ac1f80$359fc9c7 at klinder.jlc.net> "Kate"
<klindner at jlc.net> writes:
>>>>Steven B. Harris <sbharris at ix.netcom.com> wrote in article
><6raqbi$5kq at sjx-ixn3.ix.netcom.com>...
>>>> Obviously it's achievable. There are immortal plants (aspens)
and
>> animals (corals, maybe even lobsters). Their mitochondria obviously
>> don't give them any problems, and they don't get new ones from Mars.
>> Whether old mitochondria are repaired, or just produced anew and
free
>> of defect at a sufficient pace, is immaterial. For the cell, it's
>> repair either way. Any process that makes new fresh cell organelles
>> counts as "cell repair" in my book.
>>>>>>> What about the possibility of a selection process - with defective
cells
>being weeded out? Non dividing cells can't afford to weed out.
>> Kate
>
That's a real possibility except for one piece of evidence: your
germ line. There aren't that many ova to weed out. Only one (usually)
is released per cycle, and with sperm around, a reasonable fraction of
these become babies (10% ?). Those zygotes have no non-repairable
damage (aging). We don't see prematurely aging babies because the
mitochondria of the ova of the human race have been getting acumulated
free radical damage for the the last couple of million years.
