Bob C: Ferret Domestication: Where
 
Where Was The Ferret Domesticated?
 
When reviewing the "laws" governing animal domestication in an effort to
select a region where an animal could have been domesticated, one "rule"
seems paramount above all the others.  Until the modern era granted us
the ability to safely and easily transport animals from one part of the
world to another, this rule was immutable: the domestic animal was always
domesticated in an area that included the ancestor (or progenitor)
species.  In other words, domestic turkeys were domesticated in areas of
North America containing wild turkeys, guinea pigs were domesticated in
areas of South America having wild cavies, house cats domesticated in an
area having wild cats, and pigs in an area having wild boar.  You would
never find that horses were domesticated in North America, pigs in South
America, housecats in Australia, or chickens in the British Isles.  In
fact, excluding those animals domesticated in an era of modern mass
transportation, no one has ever demonstrated that an animal has ever been
domesticated in an area outside that where the progenitor originally
lived.  Thus, the ancient distribution of polecats is not only extremely
important in determining the ancestor of the ferret, but where it was
domesticated as well.  On the surface, this sounds easy, but in fact,
with polecats it is extremely difficult.
 
Most domesticated species resulted from of the domestication of a
particular sub-species, or sub-group, of the progenitor.  Ernst Mayr
considers these subspecies to be "incipient species"; that is, while
they are currently a part of the speciesthat because of some type of
isolation preventing normal gene flow, they are moving towards becoming
their own species.  With this view, any subspecies has the potential for
becoming a new species.  For our purposes, it has additional value
because subspecies have a slightly different gene distribution compared
to the remainder of the species, which allows fairly accurate genetic
identification.  So, if you can show a link between a subspecies and a
domesticated animal, then you can narrow the region of domestication to
a particular area inhabited by the subspecies.
 
This has been done with many different domesticated animals.  For
example, there are many subspecies of wild cats, but genetics,
archaeology, and morphology show the domestic house cat is a product of
the domestication of the North African subspecies of wild cat.  If we
knew which sub-species of polecat was domesticated to make the ferret,
then we would know approximately where that domestication took place.
Unfortunately, there is a slight problem with polecats in this regard.
 
The problem with the polecats can be best illustrated with a look at the
North American elk, Cervus elaphus.  In parts of North America, these elk
(also called wapiti, American elk, Roosevelt elk, Canadian elk, or even
New World red deer) are very large, even as large as Old World moose.
The record sizes of Roosevelt elk approach those of smaller horses,
which make them huge compared to many red deer found in Europe.  These
differences are not considered large enough to warrant separating the
groups into different species (although they were once, and there is
still some controversy about combining them), but it goes without saying
that the species has a great deal of variation, which is recognized by
the large number of subspecies.  This large degree of variation makes
the elk, Cervus elaphus, quite different when compared to the polecats.
 
Polecats, in contrast, have a very limited degree of variation, either
genetically or morphologically.  The European polecat, Mustela putorius,
is so similar throughout its range that currently there are NO recognized
subspecies, and it has been described by several expert geneticists as "a
species of limited genetic variability." This has some profound
implications.  In a general sense, genetic variability increases over
time as chance survivable mutations add up, so the older a species, the
more variability it displays.  A general lack of genetic variability
could mean the species is very new, that the species has a lower mutative
rate than other species, the species inhabits a homogenous environment,
or that the species is suffering from a founder's effect and the current
population evolved from a limited number of individuals.  Regardless of
the reason, it means European polecats from northeastern Europe look
pretty much like those from southwestern Europe.  And that's the rub.
 
With most domesticated species, you can compare skins, skulls, protein
electrophoresis, DNA, and mDNA studies, and pinpoint a likely geographic
location where the progenitor probably flourished.  That's been done to
isolate the progenitor of the housecat, as I've said, to a limited region
of Egypt.  The same techniques have also been used in an attempt to
ascertain the subgroup of polecats that were domesticated into the ferret
withshall we sayless than convincing results.  This forces us to put
aside the genetic studies (at least the ones done so far; future
techniques or methodology may be more convincing), and turn back to the
older techniques of looking at the history and prehistory of the polecat.
[Posted in FML issue 4768]