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| Our Evolutionary Inheritance | |
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To understand the origin
of the theory of intelligent design, we must go back to 1802 and English
theologian William Paley's famous analogy of the watchmaker. In Paley's words,
if you are walking along a beach and you find a watch in the sand, you immediately
infer that the watch is the product not of a natural process, but rather of the
skill and expertise of a watchmaker.
Until 1859, this argument had the
majority of people convinced that nature in all its complexity must indeed have
been created by some kind of a god. But that year, Darwin published The Origin
of Species. This book brought together so many observations supporting the
principle of natural selection as the main engine of evolution that it persuaded
the scientific community. | | |
| CREATIONIST ATTACKS ON EVOLUTION |
| “Intelligent design"
is the most recent and sophisticated form of creationism.
 | The
adherents of intelligent design don't believe in an Earth that is only 10 000
years old, nor in the other literal interpretations of the Bible. But they do
assert that science should be open to certain supernatural explanations for the
existence of life, and they would like to see this option taught in the schools. |
One of the main arguments offered in favour of
intelligent design is that of “irreducible complexity”. Something
is said to be irreducibly complex when the slightest component cannot be removed
from it without its immediately ceasing to function.
| The mousetrap is an oft-cited example
of an irreducibly complex object. If you take away even the tiniest part of a
mousetrap, it stops working. This irreducible complexity of the mousetrap is taken
as proof that it is the product of an intelligent design, that of the engineer
who drew up the plans for it. | |  |
In contrast, living organisms that are the product
of evolution were formed without any pre-established plan, from the “primordial
molecular soup" , through nothing more than the interaction of chance
with the various elementary forces of physics.
But the advocates of intelligent
design, such as Michael Behe, refuse to accept this construct of evolution. They
say that a living being, and in particular its cellular machinery, is too complex
to have been manufactured by natural selection. In fact, they consider it a case
of irreducible complexity and hence believe that we must admit the existence of
an “"intelligent designer"”somewhere who designed this living
machinery.
Like conventional creationists, however, the advocates of
intelligent design seem either not to know or deliberately to ignore certain basic
facts of biology, in particular the high degree of redundancy among the genes
involved in identical or similar functions. Far from being an example of waste,
this redundancy allows mutations to create genetic variability without compromising
the overall functioning of the organism. Moreover, many studies have shown how
some proteins that originally evolved to perform one function can undergo “exaptations”
that enable them to fulfil another.
These observations alone cast serious
doubt on the supposed irreducible complexity of life. Modifying or removing one
element from the structure of life, far from making it collapse, instead produces
the diversity that can potentially enable it to grow still more complex. 
The
fact that there are many molecular mechanisms that we do not understand and cannot
yet explain by an evolutionary process in no way invalidates the theory of evolution.
It may highlight the limitations of our current knowledge, but it certainly does
not constitute a proof of irreducible complexity or, as a corollary, an omniscient
creator.
The human eye is a complex structure
if there ever was one. Believers in intelligent design often cite it as an example
of an irreducibly complex organ. But biologists are now familiar with several
examples of intermediate forms of the eye, and also have much evidence
that this special structure has evolved independently several times since
life began. For example, the eye of an octopus shows much similarity to the human
eye, even though the octopus comes from a completely different genetic line and
its eye has much more limited capabilities. Thus, in response to the classic creationist
taunt, “"What good is half an eye? , the best comeback is... It's better
than no eye at all". | |
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