Gosh, I've been busy the last week and haven't done much mail, and forgot to
send this post to follow the previous one. I'm quite bummed because my car
well not be fixed until Tues at the earliest, and maybe into mid-week. So I
am stuck here in Mid-missouri over the long weekend.
As explained in my skunk post, the only real difference offered by the skunk
paper is that skunks split off the general mustelid line much earlier than
thought before, and the authors believe enough differences exist to grant
skunks their own family name, Mephitidae. (Ok, there *is* more to the
paper, but let leave it at that for now. Cool, I said 'skunks' four times
in a single sentence). I also mentioned it has little or no real bearing on
ferrets and polecats, except for those illiterate public officals who think
polecats ARE skunks, which might actually account for most (Major concession
to several friends who disagreed with my saying it was relatively
unimportant. OK, PUBLIC OFFICALS....can you say "duh?")
Some of the questions sent to me (and some are still trickling in) asked why
so many animals looked similar, but may not be related, and conversely, why
some animals are closely related, but look quite different. That's one of
the million dollar questions, and also the one most students hate to answer
in essay form. In essence, ferrets look very similar to polecats, because
they were domesticated from them. Polecats look similar to weasels, because
weasels are their closest non-polecat relatives (Technically, ferrets and
polecats ARE weasels, which is why they are called _Mustela_). Weasels look
like otters, which look like martens which look like badgers which look like
skunks and so on and so on. People as far back as Aristotle and before have
noticed this, but the true realization wasn't realized until about 150 years
ago when people started looking at animals from all over the planet, and
bringing them home and said, "Great Scott! All wild mustelids look
basically the same!"
When a ferret lays on its back, I am instantly reminded of a sea otter.
When they play, I think of mink or river otters. When they climb and jump,
I think of martens and fishers. If you look at them all at the same time,
you can kind of see the same traits shared by all, its just that in some
certain traits are more pronouced than in others. Take a ferret's long
neck. Its longer than a skunks, but maybe not quite as long (in proportion)
as a weasel's. But all mustelids have sort of long necks. And short legs.
And huge noses and flat, almost triangular heads. And stinky butts. This
is precisely the kind of stuff Lineaus was looking at when he came up with
the binominal classification system we have all come to cherish, saving
Latin and Greek from the dust heap and Jeopardy trivia.
The problem is, just because things look the same, it doesn't mean they come
from the same thing, or the species are even related. So long short slender
predators was invented at least thrice (Mustelids, Marsupials and Viverrids
[Mongeese]), flight was invented at least four times (Bats, Birds, Insects;
Reptiles), and maybe in the process of a fifth time with flying squirrels.
Swimming, who knows, but whales lost their legs at a different time than
seals who lost them at a different time than walrus. One can argue that a
trait is homologous, that is, it is shared, like placental mammals having
breasts, or if it is analogous, or not shared, like butterfly and bird
wings. The only way you really know is with history; the oldest horses have
five toes, then four, then three, and now one. So we *know* the horse' hoof
is homologous to our middle finger, because we have the fossils that
demonstrate it. (Does that mean when the Lone Ranger is astride Silver and
reared back, the horse is flipping off the viewer?)
Much of *how* an animal looks is determined by the kind of job it does to
earn its living, so animals that swim start to have the same body shape
because the same environmental forces influence both, thus a dolphin looks
like a tuna, and a ferret like a mongoose. So just because a binterong
looks like a badger, it doesn't mean they are related, they just live
similarly. And just because a river otter only superficially looks like a
ferret, it doesn't mean they are NOT closely related. DNA allows us to view
the history of the organism without having to find all the various fossil
"links" and not get fooled by similar or dissimilar morphologies. But, like
fossils, DNA can only show part of the picture, and it takes a fool to bet
heavily with only one card showing.
Look for my final stinky skunk comments in the next post.
Bob C and the 21 Missouri Carpet Sharks
[Posted in FML issue 2050]
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