[Mb-civic] On Evolution

[ean at sbcglobal.net]

http://www.nytimes.com/2006/01/01/opinion/01judson.html?ex=1136782800
&en=6e3a676f53fb66af&ei=5070

Why I'm Happy I Evolved

By OLIVIA JUDSON

New York Times Op Ed
January 1, 2006

IF chimpanzees observed New Year's Day, they would have
much to reflect on. In 2005, they joined humans,
chickens and mosquitoes, as well as less famous
occupants of the planet, on an exclusive but growing
list: organisms whose complete genomes have been
sequenced.

What would they make of this news, I wonder? Perhaps
they would resent the genetic evidence that they are
related to us. Or perhaps they would, as I do, revel in
being part of the immensity of nature and a product of
evolution, the same process that gave rise to
dinosaurs, bread molds and myriad organisms too wacky
to invent.

Organisms like the sea slug Elysia chlorotica. This
animal not only looks like a leaf, but it also acts
like one, making energy from the sun. Its secret? When
it eats algae, it extracts the chloroplasts, the tiny
entities that plants and algae use to manufacture
energy from sunlight, and shunts them into special
cells beneath its skin. The chloroplasts continue to
function; the slug thus becomes able to live on a diet
composed only of sunbeams.

Still more fabulous is the bacterium Brocadia
anammoxidans. It blithely makes a substance that to
most organisms is a lethal poison - namely, hydrazine.
That's rocket fuel.

And then there's the wasp Cotesia congregata. She
injects her eggs into the bodies of caterpillars. As
she does so, she also injects a virus that disables the
caterpillar's immune system and prevents it from
attacking the eggs. When the eggs hatch, the larvae eat
the caterpillar alive.

It's hard not to have an insatiable interest in
organisms like these, to be enthralled by the
strangeness, the complexity, the breathtaking variety
of nature.

Just think: the Indus River dolphin doesn't sleep as
you or I do, or indeed as most mammals, for several
hours at once. Instead, it takes microsleeps, naps that
last for a few seconds, like a driver dozing at the
wheel.

Or consider this: a few days after its conception, a
pig embryo has become a filament that is about a yard
long.

Or: the single-celled parasite that causes malaria is
descended from algae. We know this because it carries
within itself the remnants of a chloroplast.

It's not that I have a fetish for obscure facts. It's
that small facts add up to big pictures. For although
Mother Nature's infinite variety seems incomprehensible
at first, it is not. The forces of nature are not
random; often, they are strongly predictable.

For example, if you were to discover a new species and
you told me that the male is much bigger than the
female, I would tell you what the mating system is
likely to be: males fight each other for access to
females. Or if you discover that the male's testicles
make up a large part of his weight, I can tell you that
the females in his species consort with several males
at a time.

Suppose you find that a particular bacterium lives
exclusively in the gullets of leeches and helps them
digest blood. Then I can tell you how that bacterium's
genome is likely to differ from those of its free-
living cousins; among other changes, the genome will be
smaller, and it will have lost sets of genes that are
helpful for living free but useless for living inside
another being.

Because a cell is a kind of factory that produces
proteins, and because proteins can have a variety of
components, some of which are cheaper to synthesize
than others, you might expect that proteins that are
mass produced are made from cheaper components than
proteins that are constructed only occasionally. And
you'd be right.

The patterns are everywhere. Mammals that feed on ants
and termites have typically evolved long, thin noses
and long, sticky tongues. A virus that is generally
passed from mother to child will tend to make its host
less sick than one that readily jumps from one host to
another via a cough or a sneeze.

When I was in school, I learned none of this. Biology
was a subject that seemed as exciting as a clump of
cotton wool. It was a dreary exercise in the
memorization and regurgitation of apparently
unconnected facts. Only later did I learn about
evolution and how it transforms biology from that mass
of cotton wool into a magnificent tapestry, a tapestry
we can contemplate and begin to understand.

Some people want to think of humans as the product of a
special creation, separate from other living things. I
am not among them; I am glad it is not so. I am proud
to be part of the riot of nature, to know that the same
forces that produced me also produced bees, giant ferns
and microbes that live at the bottom of the sea.

For me, the knowledge that we evolved is a source of
solace and hope. I find it a relief that plagues and
cancers and wasp larvae that eat caterpillars alive are
the result of the impartial - and comprehensible -
forces of evolution rather than the caprices of a
deity.

More than that, I find that in viewing ourselves as one
species out of hundreds of millions, we become more
remarkable, not less so. No other animal that I have
heard of can live so peaceably in such close quarters
with so many individuals that are unrelated. No other
animal routinely bothers to help the sick and the
dying, or tries to save those hurt in an earthquake or
flood.

Which is not to say that we are all we might wish to
be. But in putting ourselves into our place in nature,
in comparing ourselves with other species, we have a
real hope of reaching a better understanding, and
appreciation, of ourselves.

-----------------------------------------------------
Olivia Judson is an evolutionary biologist at Imperial
College in London.

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