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 But when we went vertical, what happened? Anybody?
 Everything sank down to the bottom, ventured a girl on the front row.
 Exactly, I said.  And that increases the pressure on the lower abdominal
wall. So it s more prone to tear. Same thing with hemorrhoids. The lower end
of the large intestine gets more pressure now than it did in our four-footed
ancestors, so it s more susceptible to blowouts, too, which is basically what
hemorrhoids are. I heard more exclamations of disgust.  Varicose veins how
many of you have seen varicose veins? A lot of hands went up.  Now that we re
upright, the heart has a lot more work to do. It has to pump blood with enough
force to push it from the bottom of your feet all the way up to the top of
your head, a distance of five or six feet, or even more. That s a lot tougher
than pumping it three feet uphill, which is about how tall we are when we re
on all fours. It s interesting, I said.  To try to compensate for the
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circulatory problem we created when we stood up, we ve evolved this complex
system of tiny flaplike valves in our veins, whose job is to keep the blood
from flowing back downhill in the pause between heartbeats. But as we get
older, those little valves tend to leak a bit, so blood pools in the legs, and
the extra pressure makes the veins swell up and sometimes burst.
An especially tall young woman she was one of the star players on the Lady
Vols basketball team raised her hand. I pointed to her.  Yes?
 So do other mammals dogs and lions and whales not have those little valves in
their veins?
No one had ever asked that before. I had never asked it myself.  To be
honest, I said,  I don t know. I ll find out before our next class. Good
question. She beamed; it was considered a coup to stump me.
 Okay, now let s talk briefly about the pelvis and the spine, I said.  Some
of you women will doubtless have babies at some point. The good news is,
obstetric medicine is getting better all the time.
 What s the bad news? a female voice called out.
 The bad news is, babies heads are getting bigger and bigger, I said.
 Ouch, man, the same voice said.  C-section, here I come.
 Lots of women are having cesareans these days, I agreed.  Purely as elective
surgery, not because there s any medical complication that calls for it. And
frankly, skittish as I am about the idea of having my belly sliced open, if I
were a woman, I might consider it, too.
 If you were a woman, Dr. Brockton, called out a guy who had emerged as the
class clown,  I don t think pregnancy would need to be high on your list of
concerns. Much laughter ensued, including my own.
 Okay, last dumb-design feature, I said, opening the box I had brought with
me.  There are others, but we ll stop with this. I reached into the box and
fished out an articulated pelvic girdle, the bones held together with red
dental wax. The pubic bones arced together in the front; in back, the
sacrum the fused assemblage of the last five vertebrae angled between the hip
bones.  Notice the shape of the sacrum, I said.  As you get down to the end
of the spine, the vertebrae get smaller and smaller. So it s shaped like a
triangle, a wedge. Now, what do you use to split firewood?
 Um, an ax? offered someone.
 Well, yes, but I was thinking of a wedge. When you apply pressure to a wedge,
it tends to force things apart, doesn t it? You see where the hip bone, or the
ilium, joins the sacrum here on each side? That joint is called the sacroiliac
joint. When you put pressure on this wedge, the sacrum with the weight of your
entire upper body it pushes down, and it tends to force these hip bones apart,
and strain that sacroiliac joint. That s a common cause of lower-back pain in
people my age and older.
I looked directly at the intelligent-design proponent in the third row.  So
you see, I said,  there are all sorts of structural features in the human
body that suggest slow, imperfect evolution, rather than instantaneous,
intelligent design.
He raised his hand, his face showing a mixture of regret and defiance.  But
think about the eyeball, and the brain, and the heart. Those are complicated
and amazing structures. The eyeball is a marvel of optical engineering. The
brain is more sophisticated and powerful than any computer on earth. The heart
makes any man-made pump look flimsy and crude. I nodded, trying to
acknowledge that we shared an admiration for those organs.  Besides, he
challenged,  what s wrong with teaching both theories? Isn t that what
education is all about? Let both sides of the controversy make their case, and
let people make up their own minds?
 There is no controversy, I thundered.  Evolution is no more controversial
than the Copernican theory of the solar system, or the  theory that the Earth
is round. Just because a few people make an opposing claim, loudly and often,
that doesn t make the issue a legitimate scientific controversy. There is
nothing scientifically testable or provable about creation theory. Hard-core
creationists claim the fossil record fossilized evidence showing that animals
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and plants evolved over many millions of years was created right alongside
Adam and Eve. That s hocus-pocus, a fictional geologic backstory, conjured up
out of nothingness:  Fossilized remains just look millions of years old  you
said as much yourself not thirty minutes ago  because God made them look
millions of years old. Logically, you can t argue with that. It s perfectly
circular reasoning, the ultimate  because God said so. Only it s not really
God who s saying so. It s people claiming to speak for God. Well, maybe God
spoke to me this morning as I was reading the paper, and told me to tell
everyone that Charles Darwin was right, and that anybody who says otherwise
just isn t paying good attention.
 Don t get me wrong, I said.  I m not dismissing the possibility of some
higher principle or higher power operating in the universe, something that s [ Pobierz całość w formacie PDF ]