Today, we watch creatures evolving around us. The
University of Houston's College of Engineering
presents this series about the machines that make
our civilization run, and the people whose
ingenuity created them.
Wherever we aim at a
species point-blank, for whatever reason, we drive
its evolution, often in the opposite direction from
what we ourselves desire.
So says Jonathan Weiner in his new book, The
Beak of the Finch. Weiner's chapter
"The Resistance Movement" talks about the way we can
watch evolution in action as we try to eliminate
species. Bugs, germs -- even elephants -- are
unwilling to be eliminated. And few things
are as resilient as viruses.
First Weiner runs through a catalogue of evolving
micro-organisms. He tells how you barely had to
whisper the word "penicillin" over pneumonia to
kill the disease in 1941. Fifty years later, a
thousand times greater dose might not eliminate it.
Pneumonia bacteria have steadily evolved to resist
penicillin.
The reason that AIDS is such a plague is that the
AIDS virus is remarkably adept at evolving. Weiner
writes,
Individual letters in the [DNA] sequence change.
Clusters of letters change, whole chunks of DNA
disappear while other chunks insert themselves in
new places along the strand. A human body with AIDS
is like an entire Galápagos
archipelago...
AIDS not only mutates constantly. It also has a
biological diversity that gives it means for
evolving in any direction that'll protect its
survival.
So what about larger creatures? Since poachers go
after elephants with large tusks, those tusks
threaten elephant survival. Today, one in ten of
all young female African elephants has no tusks at
all. Those females are pretty safe from hunters.
As the slaughter goes on, we find half the
surviving older females with no tusks.
They're the ones who keep reproducing. Long-tusked
males were once the only ones with harems. Now
we're finding tuskless males with harems. The
survival of the fittest is rapidly creating a breed
of elephants that's of no more use to hunters
who've been exterminating them.
An old axiom says that fishermen keep the big ones
and throw the little ones back into the sea.
Fishermen's nets are designed to do that -- to let
the little ones slip through. Now, as the fishing
industry grows, species of cod, salmon, and red
snapper are getting smaller and smaller.
We humans mutate as well. Once we'd become
technological creatures, some two million years
ago, our brains began growing. Brains hadn't been
so important to our survival, but now they were.
Indeed, human survival depends upon our ability to
adapt to viral and bacteriological attack. Diseases
like Ebola, which kill us quickly, are like good
elephant hunters. They have a hard time keeping a
foothold. It's diseases that let us survive for
quite a while that're more dangerous -- sickle cell
anemia and AIDS.
And we're back to Weiner's remark that aiming
point-blank at a species drives its survival. It's
a neat paradox, one we'd better understand before
we try to wipe out any of the pests that dog our
lives.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
