“Incredible” is not “impossible”

Originally published 18 May 2008

Let’s get this straight once and for all: Evo­lu­tion by nat­ur­al selec­tion is not a the­o­ry. It is a fact! Sci­en­tists are not slav­ish­ly attached to Dar­win­ism because of some anti-reli­gious prej­u­dice or desire to evade God’s moral law, as the fun­da­men­tal­ist preach­ers insist, but because it is a log­i­cal necessity.

Hear me out.

Con­sid­er any sys­tem, bio­log­i­cal or arti­fi­cial, that pos­sess­es three properties:

1. Enti­ties repro­duce from one gen­er­a­tion to the next with inher­it­ed char­ac­ter­is­tics (e.g., phys­i­cal, behav­ioral, or mathematical).
2. Vari­a­tions of inher­it­ed char­ac­ter­is­tics some­times occur (by muta­tion, sex­u­al mix­ing, etc.).
3. Vari­a­tions are act­ed on by some kind of selec­tion (dif­fer­en­tial sur­vival, sex­u­al pref­er­ence, com­put­er algo­rithm, etc.).

If these three con­di­tions pre­vail, evo­lu­tion is not just pos­si­ble, it is inevitable. Any­one who doubts that the three con­di­tions apply to liv­ing organ­isms has not been pay­ing atten­tion or is will­ful­ly igno­rant. Dar­win­ian evo­lu­tion is a log­i­cal neces­si­ty for life on Earth.

Whether evo­lu­tion by vari­a­tion and nat­ur­al selec­tion is suf­fi­cient to explain the full com­plex­i­ty of life on Earth remains an open ques­tion. Advo­cates of intel­li­gent design think not, but they have yet to offer a sin­gle exam­ple of a bio­log­i­cal fea­ture that can­not in prin­ci­ple be account­ed for by nat­ur­al selec­tion. Until they do, we need not take their reli­gious­ly-moti­vat­ed cri­tique seriously.

One respect­ed sci­en­tist who believes some­thing beside nat­ur­al selec­tion is at work is Stu­art Kauff­man of the Uni­ver­si­ty of Cal­gary. His sem­i­nal 1993 book The Ori­gins of Order ques­tioned the pre­vail­ing opin­ion that nat­ur­al selec­tion is suf­fi­cient to explain “the over­whelm­ing and beau­ti­ful order which graces the liv­ing world.”

Kauff­man set out to show that sources of self-orga­ni­za­tion exist through­out the nat­ur­al world: The six-point­ed snowflake and spher­i­cal rain­drop are sim­ple exam­ples. In high­ly orga­nized sys­tems, such as bio­log­i­cal organ­isms, these nat­ur­al sources of order dri­ve nature towards ever more com­plex forms, he maintains.

“None can doubt Dar­win’s main idea,” Kauff­man writes. “If we are to con­sid­er the impli­ca­tions of spon­ta­neous order, we must cer­tain­ly do so in the con­text of nat­ur­al selec­tion, since biol­o­gy with­out it is unthink­able.” But Dar­win is not enough, he insists.

Life has not been cob­bled togeth­er by nat­ur­al selec­tion act­ing on ran­dom muta­tions, he says. We are not Rube Gold­berg machines slapped togeth­er piece by piece by evo­lu­tion. Rather, life is “a nat­ur­al expres­sion of the stun­ning self-orga­ni­za­tion that abounds in very com­plex reg­u­la­to­ry networks…Order, vast and gen­er­a­tive, aris­es naturally.”

In oth­er words, we are more than the sum of our chem­i­cal parts. Life is an emer­gent phe­nom­e­non that arose when chem­i­cal sys­tems on the ear­ly Earth increased beyond a “thresh­old of com­plex­i­ty.” The sub­se­quent his­to­ry of life unfolds at least part­ly as a con­se­quence of complexity.

Kauff­man and his like-mind­ed col­leagues use pow­er­ful com­put­ers to explore how com­plex inter­con­nect­ed sys­tems behave. They have demon­strat­ed how com­plex arrays of sim­ple ele­ments can cat­alyze their own self-orga­ni­za­tion, and these com­put­er sim­u­la­tions show intrigu­ing par­al­lels with the real-world his­to­ry of life. If we can dis­cov­er the laws of self-orga­ni­za­tion, says Kauff­man, we will under­stand how our bod­ies devel­oped from a sin­gle fer­til­ized egg, and how our species emerged over bil­lions of years from pre­bi­ot­ic chemicals.

He writes: “Almost 140 years after Dar­win’s sem­i­nal book, we do not under­stand the pow­ers and lim­i­ta­tions of nat­ur­al selec­tion, we do not know what kinds of com­plex sys­tems can be assem­bled by an evo­lu­tion­ary process, and we do not even begin to under­stand how selec­tion and self-orga­ni­za­tion work togeth­er to cre­ate the splen­dor of a sum­mer after­noon in an Alpine mead­ow flood­ed with flow­ers, insects, worms, soil, oth­er ani­mals, and humans, mak­ing our worlds together.”

Well, yes indeed. But fif­teen years have passed since the pub­li­ca­tion of The Ori­gins of Order and Kauff­man and col­leagues have yet to artic­u­late the pre­sumed laws of self-orga­ni­za­tion or sup­port their neces­si­ty with empir­i­cal data. Frol­ick­ing in an alpine mead­ow is not enough. Mean­while, the Dar­win­ian par­a­digm con­tin­ues to be the most fruit­ful tem­plate for bio­log­i­cal research and march­es from suc­cess to suc­cess. Ran­dom muta­tion and nat­ur­al selec­tion have even been used to design elec­tron­ic cir­cuits, includ­ing devices for which patents had been pre­vi­ous­ly grant­ed to human inventors.

Per­haps there is more going in the world of liv­ing crea­tures than the Dar­win­ian par­a­digm sup­pos­es. I’m rather inclined to this view myself. But my intu­ition, or the intu­ition of some­one as bright as Stu­art Kauff­man, does not con­sti­tute proof. Evo­lu­tion by nat­ur­al selec­tion is a nec­es­sary char­ac­ter­is­tic of life as we under­stand it today. Whether it is a suf­fi­cient to explain the full­ness of life remains to be seen. Those who think not have yet to make their case.