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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.

                            <td class=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."

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.)

abstract drawing of human eye
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.

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.


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? diagram of eye showing lense, retina and blood vessels
Cross-section of a
human eye
  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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