Today, we realize that life is instability. 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.
You're an alien observer on
Mars. You have the same instruments we have on
Earth. You want to know if there's any form of life
in the solar system. Scientist James Lovelock asks
how you'd decide.
First, you'd turn your telescope from planet to
planet. Most are drab. Just one has a lovely blue and white
luminosity. That's Earth. It's very pretty, but
is it life-bearing?
Next you'd use spectroscopic chemical analysis. And
you'd find something very strange. Only one planet
has any oxygen to speak of in its atmosphere.
That's Earth, and it has 21 percent.
Is oxygen needed to support life? We need it, but
other life forms might not. So you still don't
know. But wait: That oxygen will burn anything in
sight. Combustion has gone to completion on every
other planet. That means they're all as stable as
the ashes in last night's fireplace.
Only Earth stays volatile and unstable. Only Earth
rides the knife edge of chemical balance.
Oxygen-generating processes go on, all the time.
Fires and animal metabolism use up oxygen, all the
time. Violate that balance just a little -- let the
oxygen in air rise to 25 percent -- and plant life
would become so much kindling wood. Let it drop
just a little, and we'd all suffocate.
And there, says Lovelock, is what defines life.
Every living thing uses corrective feedback to
sustain the equilibrium of its own unstable self.
Indeed, he says, Earth not only shows life-likeness
in its component parts. Earth as a whole is a
lifelike organism. Lovelock even gives that
organism a name. He calls it Gaia.
So feedback control of instability is the hallmark
of life. That's what would tip our hand to the
observer on Mars. Life is self-control, and
self-control is freedom. We find analogies
everywhere. For example:
We've craved the freedom to fly as long as we've
had to walk this Earth. First we tried to imitate
the birds with flapping wings. We failed. Then we
tried to create stable powered gliders. We failed
Finally the Wright Brothers saw what no one else
had seen. They invented an unstable airplane that
could be controlled and corrected at every instant.
And that's just how birds fly.
It's what we also do every moment. We correct
ourselves from each instant to the next. We chance
error and fix it in mid-flight. Then we're alive.
Earth constantly makes and corrects errors while
She sustains the life that comprises Her. And
that's what we have to do if we mean to be wholly
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
Lovelock, J.E., Gaia: A New Look at Life on
Earth. Oxford: Oxford University Press, 1987
(an updated reprinting of a 1979 book.)
Joseph, L.E., Gaia: The Growth of an
Idea. New York: St. Martin's Press, 1990.
Beyond Lovelock's arguments, I'm grateful for
several conversations with people who helped me
shape this idea. They are Judy Myers, Janet Allen,
Farrokh Mistree, Karen Hall, and Donald Hall. For
more on Gaia, see Episode 699.
The Engines of Our Ingenuity is
Copyright © 1988-1997 by John H.
From The Art of Flying,
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