I followed with interest the FML discussion about a month ago on "how long
do ferrets live." Like many ferret owners, I was rather alarmed when I first
discovered that the average lifespan for a ferret is about 5-7 years.  (I
raise rabbits ... Angoras for their wool ... and my bunnies live longer than
that.) My first pair of ferrets, Willie (a blind albino male found in a
dumpster) and Mattie (a young sable female adopted from a Southern Oregon
Humane Society), bore out this fact.  At about six years of age both came
down with what I now know was adrenal cancer ... within days of each other
it seemed ... another puzzling coincidence which has made me wonder whether
a virus or other biological agent "triggers" the illness ... but that is
another story.  Both ferrets were euthanized about a year later when their
symptoms became so bad that it was pure agony to watch them struggle from
day to day.  I now understand a lot more about this cancer... and hopefully,
if I ever have to go through the ordeal again (knock on wood), I will be
able to better assist the little guys.
 
Anyway, getting back to aging ... I remember reading a number of
commentaries on why ferrets have such short lifespans.  Several of them
discussed the high metabolism rate of ferrets, and that this high
rate-of-living sorta wears them out early.  This week, I read with interest
an article in the January 1998 issue of the Smithsonian, entitled "Solving
the Aging Puzzle." It addressed the issue of why living things age at
different rates.  One of the hypothesis thrown out was the high metabolism
one.  Apparently, hummingbirds can have a heartbeat rate of 1200 beats or
more per minute and yet can survive in the wild for up to 14 years ...
double that of the average ferret.  Opossums, on the other hand, age at "a
pathetically rapid rate" and seldom live longer than a few years.  The
porcupine, only slightly larger and similar in metabolism to the opossum,
"can easily live to be 20." The gerontologist profiled in the article,
Steven Austad, hypothesized the following.  To predators, the slow-moving,
easy-to-spot opossums are lunch on four feet.  He "suspects that most
opossums have an inherited trait that causes them to age rapidly starting at
2 or 3." In the wild, an opossum would seldom survive long enough to be
affected by this inherited trait to age quickly.  Therefore, this "death"
trait remains in the gene pool since there is no evolutionary pressure to
remove it.  Porcupines, on the other hand, have quills to ward off enemies
and thus survive longer (hummingbirds have wings to evade danger).
Therefore, a porcupine carrying a gene that causes early death has fewer
offspring than its longer-lived buddies do; consequently, its "death" gene
is gradually crowded out of the gene pool.  Steven Austad surmises that "the
longest-lived animals tend to have some special protection from accidental
death." If this is the case then I wonder what predisposes the ferret to
accidental death at an early age, thereby propagating an "early aging" gene
within their gene pool ... if indeed ferrets do harbor such a gene.  Could
it be their natural curiosity?  My ferrets, I know, will actively search out
and explore places I wouldn't dream of exposing a gloved hand to.  Could it
be their inclination to "stand their ground" and confront danger head-on,
rather than to run and hide and perhaps survive longer (like a rabbit)?
Could it be illnesses, such as their predisposition to adrenal cancer, that
kills off those that survive danger?  Or is an illness, such as adrenal
cancer, itself some sort of "early death" trait?
 
I don't have any answers, but I wonder about what causes what and yes, I
very much wish that the little devils would hang around a whole lot longer
than they genetically do.
 
Theresa ... caretaker of Elly and Rudy (both rambunctious 4 year olds)
[Posted in FML issue 2195]