Science Talk

Budikka666 · Guest

In _Seed_ magazine's (www.seedmagazine.com/) August edition, PZ Myers
of www.scienceblogs.com/pharyngula has an article on cervical
vertebrae. No, get your mind out of the gutter, it has nothing to do
with the cervix. It has to do with the neck (although both words
derive from an old English word for neck)
http://tinyurl.com/2ppmp3

This same question is also tackled here:
http://8e.devbio.com/article.php?ch=11&id=115

PZ tells us that the rule for mammals is seven cervical vertebrae, no
more, no less:
"Plesiosaurs, those aquatic reptiles of the Mesozoic, are
impressive: Some species had about 40 cervical vertebrae. Modern birds
also have representatives with numerous cervical vertebrae, up to 25
in swans. Diplodocids, the characteristic long-necked herbivorous
dinosaurs, had 12 to 13.
"Giraffes have seven.
"Even stranger, imagine any short-necked mammal-a dolphin, a
mole, a cow, a human being-and you get exactly the same answer:
Typically, they all have just seven vertebrae, no matter how many
millimeters or how many meters long their neck might be. (There are
some obscure exceptions: Manatees and two-toed sloths have six
cervical vertebrae, and three-toed sloths have nine. Otherwise, seven
is the rule for mammals.)"

I recall reading somewhere that giraffes actually have one more
cervical vertebra, but most sources cite seven. I also read that
while technically they do have seven, one of the thoracic vertebrae
has adopted a "cervical persona" so that whilst they do only have
seven vertebrae technically speaking, the uppermost thoracic vertebra
takes on the role of the lowermost cervical vertebra. I think I'll
have to email PZ and ask him about that.

Anyway, he adds, "The number of thoracic vertebrae in mammals ranges
between nine and 23, but almost always the number of cervical
vertebrae is seven."

So why is this rule so strictly enforced, and why only in mammals?
And yes, it is strict. Sometimes the seventh cervical vertebra has
ribs, thereby defining it as a thoracic vertebra, but this is rare:
"Evolutionary development biologist, Frietson Galis and others
examined fetuses that had been spontaneously aborted, or medically
aborted due to detected fetal abnormalities, and discovered that an
astonishing 55 percent of them had ribs on the seventh vertebra."

So this is an abortion issue. You get those ribs creeping up and your
life expectancy creeps down. "Children with cervical ribs have been
found to have a 120-fold greater chance of developing certain cancers
over children with seven normal cervical vertebrae.
"It's highly unlikely that any benefit from an incremental change
in the number of neck bones could compensate for the associated 80
percent mortality rate before one year of age"

Is this a design? Why would a perfect, intelligent, benevolent god
who had all eternity in which to work, and infinite resources upon
which to call make such a blunder in design whereby having those ribs
creep up by just one vertebra is effectively a death sentence?

Clearly the designer doesn't care about abortion or he would have
designed this a lot better. On the other hand, perhaps he's really
just a lousy designer?

Or you could simply dispense with the fiction of intelligent design
and come to the rational realization that there's no design, only
undirected, unintelligent nature following the laws of physics, and in
turn the laws of chemistry, which are not at all random.

Budikka