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A concept known as "intelligent design"
(ID) has been used as an argument against Darwinism
from the publication of On the Origin of Species
in 1859 right up to the present day. Quite simply,
ID states that living organisms must be the product
of careful and conscious design, so perfectly
formed that they cannot be explained by the random
workings of evolution alone. Modern ID theorists
contend that this is a new and novel scientific
alternative to evolution.
ID, however, has been rejected by the modern
scientific community for the same reasons that
it failed in the 19th century. When closely examined,
the living world is filled with evidence that
complex organisms not only could have evolved
through evolution's trial-and-error mechanism,
but must have done so, because their structure,
their physiology, and even their genetic makeup
are all inconsistent with the demands of intelligent
design.
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 Kenneth
Miller is a cell biologist and professor of biology
at Brown University and coauthor of widely used
high school and college biology textbooks. He has
also written Finding Darwin's God: A Scientist's
Search for Common Ground Between God and Evolution
(1999). He served as an advisor to the PBS Evolution
series and is featured in the first show, "Darwin's
Dangerous Idea." |
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This essay has been adapted from the article
"Life's Grand Design," which appeared
in Technology Review: MIT's Magazine of Innovation
in February/March 1994. (Boldface added.)
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The
human eye is
an organ of great
complexity, both in
structure and function. |
The case for evolution does not depend, even for a minute,
upon a claim that living organisms are not complex or
intricate. One case in point is a structure often cited
as a perfect example of intelligent design: the human
eye. |
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The eye, like a top-of-the-line modern camera, contains
a self-adjusting aperture, an automatic focus system,
and an inner surface that minimizes the scattering of
stray light. But the sensitivity range of the eye, which
gives us excellent vision in both sunlight and moonlight,
far surpasses that of any film. Its neural circuitry
enables the eye to automatically enhance contrast. And
its color-analysis system enables it to quickly adjust
to lighting conditions (incandescent, fluorescent, or
sunlight) that would require a photographer to change
filters and films.
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The proponents of intelligent design assert that the combination
of nerves, sensory cells, muscles, and lens tissue in
the eye could only have been "designed" from
scratch. After all, how could evolution, acting on
one gene at a time, start with a sightless organism and
produce an eye with so many independent parts, such
as a retina, which would itself be useless without a lens,
or a lens, which would be useless without a retina? |
Cross-section of a
human eye |
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In
a Darwinian world, the exquisite adaptations and specializations
of living organisms are the products of natural selection,
a process whereby the genetic variations -- such as size,
shape, and coloration -- that give individuals the best
chance to survive and reproduce are passed on to subsequent
generations. |
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