[ExI] Human Aging

[Ben]

<natasha at natasha.cc>  asked:

 >1.       When does the body starts aging (conflicting views suggest 
directly
 >after puberty, others say 20-ish);

That's like asking when gravity starts pulling.   We're ageing all the 
time we're alive.  Even before then.  Egg cells age, sperm age, 
everything ages all the time.


 >
 >2.       When does the body start preparing for death (conflicting views,
 >and some suggest after menopause and andropause);

It doesn't, any more than a tractor prepares to break down.


 >
 >3.       If the body regenerates itself every seven years...

It doesn't.  I don't know where that idea comes from, but it's not a 
very useful one.  Different cell types have different turnover rates.  
Averaging them is a pretty pointless exercise, and probably not even 
possible.  An 80-year-old will likely still have some cells they had at 
birth.  Even the idea of atoms and molecules being replaced is not 
realistic, because some of them get trapped in forms that the body can't 
break down.  If you track an atom of Carbon that gets into a Lipofuscin 
granule in a heart muscle cell when you're 20, it's probably still going 
to be there when you're 70.


Ben Zaiboc