Intelligent design happens naturally

Originally published 14 May 2002

What a jum­ble! I’m sit­ting in a doc­tor’s exam­in­ing room wait­ing for a check­up. On the wall is a poster chart of the human diges­tive sys­tem. The first thing I’m remind­ed of is my sock and under­wear draw­er. Every­thing thrown in a heap, all twisty and turny. No two socks that match. A long sock balled up with a short one and a pair of skivvies.

The draw­er of a slob who can’t be bothered.

When you think about it, it’s a won­der how any­thing makes it from one end of the diges­tive tract to the oth­er. An engi­neer might sort it out. Roll that small intes­tine up into a nice neat coil. Straight­en out those kinks in the large intes­tine. Can you imag­ine the exhaust sys­tem of your car in such a tangle?

The human ear is anoth­er body part that could use the atten­tions of a good engi­neer. It seems aston­ish­ing­ly com­plex com­pared to a the tiny lit­tle micro­phone that lets my lap­top com­put­er respond to sound. Ham­mer, anvil, and stir­rup: Where did those crazy lit­tle mech­a­nisms come from? Five sep­a­rate mem­branes. And three fleshy loops that seem, on the face of it, superfluous.

OK, admit­ted­ly the ear has a goofy Rube Gold­berg inge­nu­ity about it, but does it real­ly need to be so com­pli­cat­ed? It’s no sur­prise that my doc­tor does­n’t have a clue why I have ring­ing in my ear, or how to fix it.

And while we are at it, what about the human male’s use of the same penile pas­sage for both repro­duc­tion and excre­tion. In prim­i­tive ani­mals the use of one duct for both func­tions can be explained as a mat­ter of effi­cien­cy, but in the high­er ani­mals the asso­ci­a­tion of the two sys­tems can lead to prob­lems. An enlarged prostate, for exam­ple, press­es against the blad­der, caus­ing uri­nary prob­lems as well as repro­duc­tive malfunction.

In the course of evo­lu­tion, this dual use of a sin­gle duct has been mod­i­fied in females, with the shared pas­sage being grad­u­al­ly short­ened. In most female mam­mals, urine from the ure­thra pass­es only through the final part of the vagi­na. In human females and their clos­est rel­a­tives among the apes, the uri­nary ori­fice has moved com­plete­ly out­side the vagina.

In his book, The Pony Fish’s Glow, evo­lu­tion­ist George Williams draws atten­tion to anoth­er wacky fea­ture of the male repro­duc­tive-excre­to­ry sys­tem — the absurd­ly long tubes that car­ry semen from the testes to the adja­cent penis, which make an unnec­es­sary round trip up into the body, then back down again.

Accord­ing to Williams, in the course of ani­mal evo­lu­tion, the tes­ti­cles descend­ed from deep inside the body to the scro­tal sac behind the penis, pre­sum­ably to pro­vide cool­ing for the sperm. As the tes­ti­cles moved toward the groin, the tubes con­nect­ing them to the penis should have log­i­cal­ly short­ened. But the pip­ing got hung up around the ureters con­nect­ing the kid­neys to the blad­der, like a gar­den­er’s hose that gets caught around a tree.

The testes-penis con­nec­tion makes no sense at all from a design point of view, but it is read­i­ly explained by evo­lu­tion­ary biology.

I guess the point I’m try­ing to make is that much of the human body is an engi­neer’s night­mare, show­ing lit­tle in the way of intel­li­gent design: which is just what you’d expect if our bod­ies evolved by a process of incre­men­tal changes act­ed upon by nat­ur­al selec­tion. The thing about evo­lu­tion is this: Inevitably it moves toward ever­more fine­ly adapt­ed organ­isms, but the end is not fore­or­dained and the jour­ney is some­thing of a drunk­en stagger.

Now, before you accuse me of toss­ing an Intel­li­gent Design­er out of the pic­ture, con­sid­er this: For all of the improve­ments an engi­neer might sug­gest for the human body, the body is still a thing that no engi­neer could hope to equal. Fab­u­lous­ly resilient. Capa­ble of stun­ning feats of endurance. Exquis­ite­ly attuned to the envi­ron­ment. Agile, dis­ease-repelling, self-repair­ing, pur­pose­ful, cunning.

Evo­lu­tion by nat­ur­al selec­tion, for all of its jer­ry-rigged solu­tions, for all its failed exper­i­ments and blind alleys, is a won­der­ful­ly effi­cient way to pop­u­late a uni­verse with diverse and inter­est­ing crea­tures. If I were an Intel­li­gent Design­er, and I had a hun­dred bil­lion galax­ies (at least) to fill with won­ders, I can think of no way more effi­cient to do it than by genet­ic vari­a­tions and nat­ur­al selec­tion of self-repro­duc­ing organisms.

In fact, engi­neers are increas­ing­ly using exact­ly this strat­e­gy to solve com­plex prob­lems of design. Start with a pro­to­type and a func­tion­al envi­ron­ment, make ran­dom changes, rein­force the ones that work, elim­i­nate the ones that fail. Do all of this in mul­ti­ple gen­er­a­tions on a high-speed com­put­er. Let the com­put­er find the best adapt­ed design. What you end up with may not be what you would have designed in the tra­di­tion­al way, but it’s usu­al­ly better.

You want intel­li­gent design? Try evolution.