Posted 05 December 2007 - 05:11 AM
Remember this fact though, cell division does shorten lifespan and unless you have stem cells flowing through your bloodstream or present everywhere, healing occurs by cell division (in situ) only. This cuts into the lifespan of the cell.
Consider it something like a prepaid service, where each cell division lowers lifespan of the resultant cell. The resultant graph of lifespan verses no. of divisions undergone would go down in a geometric curve and would drag down the person's lifespan as well, if the amount of healing to be done is high.
As Kyuubi's chakra accelerates healing, it promotes cell division. By itself the effect is small and does not endanger Naruto in any way. But if he gets dependent on the healing power, he'll push himself harder in training, causing damage to muscles and tissues, which keep getting repaired without being noticed. As the level of training increases the level of healing would increase as well, effectively reducing Naruto's lifespan even if outer damage cannot be seen. The most damage of course would be a direct result of KT4, which burns off the body even as it tries to repair it.
To say it all, jinchuuriki might have different kinds of abilities and powers that help them survive longer in a conflict, they age faster than normal humans and thus their overall life expectancy is lower.
Now, as for our neighbourhood genetic engineer Kyuubi, genetic splicing of any magnitude may actually kill the host due to tissue rejection, so he/she/whatever would refrain from doing so. Plus for a bijuu of his calibre, why would he care for such a weak container when he can usurp his host's consciousness and gain control of his body?
QUOTE (The Dream Cat @ "A Dream Of A Thousand Cats")
"Many, many seasons ago, cats truly ruled the world.
We were larger then, and the whole world was created for our pleasure. We roamed as we would, taking what we wanted.
In those times, humans were tiny creatures, no larger than we are now.
And humans would groom us and feed us and pet us."