Life's complexity defies demand for a designer
08/05/2002
By TOM SIEGFRIED / The Dallas Morning News
Life is complicated, and explaining it is more complicated still or so it would seem. Even some religious approaches employ elaborate rationales to explain life's complexity.
Among the most famous of such religious explanations came from William Paley, the English theologian who deduced God's existence by comparing life to a timepiece.
If you find a watch on the ground, he wrote in 1802, you can see that it's nothing like a rock. The watch's parts are clearly "put together for a purpose," adjusted to produce "motion so regulated as to point out the hour of the day."
The inevitable inference, Paley concluded, was "the watch must have a maker ... who comprehended its construction, and designed its use." And so life, full of features with obvious purposes, must also have been designed by some intelligent agent. "Design," Paley wrote, "must have a designer."
Even today, Paley's argument survives among advocates of "intelligent design" as the source of life's diversity and complexity. But Charles Darwin, who admired Paley's philosophy, reached a different conclusion. Natural selection of the fittest organisms, working without design, could also craft features serving useful purposes for living organisms. Modern science embraced Darwin's solution, as summarized by the British biologist Richard Dawkins: "The analogy between ... watch and living organism is false. ... The only watchmaker in nature is the blind force of physics."
But can the simple laws of physics really produce devices of such complexity? Surely a watch could not assemble itself from random molecules of metal and plastic. How could nature on its own hope to produce something really complicated, like a human brain?
The answer, says physicist Stephen Wolfram, is that making a brain is easy. Crafting a timepiece is hard. You need a designer, he says, not to produce complexity, but to ensure simplicity.
A watch, after all, exhibits nothing like the complexity of life, Dr. Wolfram points out in his recent book, A New Kind of Science. Keeping time requires, above all else, absolutely regular motion to guarantee near-perfect predictability. Complexity introduces deviations from regular motion, rendering a clock worthless. Nature, left to its own devices, produces complexity with wild abandon.
Dr. Wolfram's conclusions stem from thousands of experiments with simple computer programs. He finds that very simple programs (analogous to the simple laws of physics) generate vast complexity with no "design" at all. So all the complexity in nature, including life, could have appeared naturally through the operation of simple rules or laws.
"One of the most striking features of the natural world is that across a vast range of physical, biological and other systems we are continually confronted with what seems to be immense complexity," Dr. Wolfram writes. "Throughout most of history it has been taken almost for granted that such complexity being so vastly greater than in the works of humans could only be the work of a supernatural being. But my discovery that many very simple programs produce great complexity immediately suggests a rather different explanation."
If natural processes merely act like simple computer programs and Dr. Wolfram believes that they do then complexity should appear automatically, with no purpose behind it. Human artifacts, such as watches or other devices designed for particular purposes, do not exhibit similar complexity precisely because they are designed for a specific purpose.
"The reason that such complexity is not usually seen in human artifacts is just that in building these we tend to use programs that are specially chosen to give only behavior simple enough for us to be able to see that it will achieve the purposes we want," Dr. Wolfram points out.
Complexity, in other words, is natural, requiring no design. Purpose requires simplicity, and simplicity demands design.
Dr. Wolfram, therefore, concludes that the complexity of life arises from the natural operation of some simple computer programs underlying the laws of nature. In fact, he believes, most of life's complexity stems from this source, rather than from Darwin's natural selection.
Of course, most biologists won't buy that part of Dr. Wolfram's program. But his insight nevertheless offers a new context for understanding life's complexity. There is no doubt that genetic "programs" of some sort operate within organisms to guide their development and daily life. Maybe Darwinian natural selection chose some simple programs over others early in life's history.
In any event, Paley's original inference was rooted in an intuition that Dr. Wolfram's findings have shown to be erroneous.
"The intuition that if it's complex it had to have a complex process of design ... is a false premise," says Terrence Sejnowski, a neuroscientist familiar with Dr. Wolfram's work. Simple rules can produce vast complexity without any purposeful design at all. Design, in fact such as that of a watch is a hallmark not of the complexity found in life, but of the simplicity found in trinkets and tools.
Comparing evolution with watchmaking is therefore a doubly false analogy. There is no design or purpose underlying life's complexity, and there is no true complexity in a designed and purposeful watch.
"Nature may not be a blind watchmaker," says Dr. Sejnowski. "But maybe nature is a blind programmer."
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Tom Siegfried |
Tom Siegfried is a science editor for The Dallas Morning News. |