From: Wade T. Smith (email@example.com)
Date: Tue 17 Jun 2003 - 22:15:31 GMT
Evolution was, and is, a great notion
By Chet Raymo, 6/17/2003
What was the greatest scientific idea of all time? The answer, I think,
is clear: Evolution by natural selection, conceived more or less
simultaneously by Charles Darwin and Alfred Russel Wallace in the
mid-19th century. It was their genius to imagine a way diverse
organisms could arise from simple ancestors by purely natural process.
As Darwin and Wallace clearly understood, if three conditions apply --
replication, variation (mutation), and competition for limited
resources -- evolution is not just a possibility, it is a logical
What was not understood in their time was the genetic basis for
replication and mutation, so their premises were based on a certain
amount of speculation. Today, all three conditions for evolution are
well understood and amply confirmed.
Nevertheless, a conceptual difficulty remains, as it did for Darwin.
How can certain complex structures with multiple interacting
components, such as the human eye, arise from any conceivable
combination of random, single-function mutations of an organism's genes?
Opponents of Darwinian evolution call this the problem of ''irreducible
complexity.'' The chance that a combination of random mutations might
produce something as complex as the human eye is vanishingly small,
they say. Complexity requires a designer. Evolution may occur, but it
will go nowhere unless an intelligent outside agency intervenes at key
points in the process.
The argument is not new. As long ago as 1800, the English theologian
William Paley used the example of a man walking on a heath who finds a
pocket watch among the pebbles. The man might consider the pebbles to
be a product of natural causes, Paley stated, but he would never
believe the watch to be other than the product of intelligent design.
Until recently, there was no way for evolutionists to persuasively
answer this objection. It was clear that organisms might find ways to
combine simpler, independently-evolved functions to perform complex
operations, but the fossil record is too spotty to demonstrate the
supposed intermediate steps toward complexity.
Enter the high-speed digital computer.
It is now possible to create artificial organisms -- self-replicating
computer programs -- that meet the three requirements for evolution:
replication, random mutation, and competition. These artificial
organisms go through thousands of generations in minutes or hours of
computer time, and every step of the process can be observed. They
evolve surprisingly complex structures.
In the May 8 issue of Nature, an interdisciplinary group of researchers
at Michigan State University and the California Institute of Technology
describe one such experiment.
They created a simple, self-replicating, computer-viruslike ancestral
''organism,'' subject to random mutations of its program. The organism's descendants compete in cyberspace for the ''energy'' necessary to execute instructions. They are rewarded according to their evolved ability to perform logical operations that were not part of the original program.
As in nature, some mutations were beneficial, some were neutral, and
many were deleterious. Nevertheless, remarkable logical complexity
emerged. An ancestor that could only make copies evolved descendants
able to perform multiple logic functions requiring the coordinated
execution of many program instructions.
As these computer experiments continue -- and this is not the first --
the insights of Darwin and Wallace become ever more compelling.
For example, Stanford University's John Kosa and colleagues have
programmed a powerful computer to use replication, mutation and
competition to digitally evolve useful electronic circuits, including
many devices for which patents had been previously granted to human
inventors. They anticipate that a patent might soon be granted for an
invention that is entirely their computer's own.
Opponents of Darwinian evolution might object that these evolutionary
computer programs are themselves products of human intelligent design.
Yes, but so what? They still demonstrate that complex organisms can
arise from simple ancestors by purely natural process.
Replication, variation, and competition can indeed produce
unanticipated complexity. In fact, one rather fears the time when
malicious hackers let loose into cyberspace destructive viruslike
artificial organisms that employ Darwinian principles to evolve ever
more resourceful ways of eluding our efforts to control them.
Chet Raymo teaches at Stonehill College. His most recent book is ''The
Path: A One-Mile Walk Through the Universe.''
This story ran on page C2 of the Boston Globe on 6/17/2003. © Copyright
2003 Globe Newspaper Company.
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