Repost­ed from the old TfK because it’s fun.

In KU’s intro­duc­to­ry biol­o­gy lab about evo­lu­tion, the stu­dents are asked (not my phrasing):

In the ver­te­brate ani­mal clade, jaws have evolved from car­ti­lage-like rods asso­ci­at­ed with gills. In jaw­less ances­tral ver­te­brates, as well as extant jaw­less species such as hag­fish and lam­preys, the func­tion of these skele­tal rods was/is to sup­port the gills. Jaws func­tion to grasp and chew, their suc­cess is notable, as jaws are still present in most extant ver­te­brates. If an engi­neer were put to the task of design­ing “jaws,” would the out­come be the same as the evo­lu­tion­ary out­come we observe in jawed ver­te­brates? Explain your reasoning.

I usu­al­ly men­tion that the rep­tile jaw con­sists of three bones on each side, while the mam­malian jaw has only one bone on each side. The oth­er two bones migrat­ed into the inner ear. We have fos­sils with an artic­u­la­tion on the third bone and anoth­er on the first, a per­fect tran­si­tion. “If you designed a jaw,” I ask con­fused stu­dents, “would you start by mak­ing real­ly good gills, then take the parts of that to build a jaw, then take some parts of that away and use them to build a microphone?”

They usu­al­ly say that they would­n’t. The point is that even if the end result were iden­ti­cal to jaws we see now, the process that leads to the final prod­uct is very dif­fer­ent. An engi­neer has a goal and works toward it. Evo­lu­tion can see maybe half a step ahead, and real­ly can only look back­ward. What­ev­er works, sticks, what­ev­er does­n’t work, dies out. The exist­ing struc­tures we see are depen­dent on his­tor­i­cal contingency.

For real­ly con­fused stu­dents, I draw on a point Stephen Jay Gould made in Eight Lit­tle Pig­gies (in the essay by the same name), that the num­ber of fin­gers we have is entire­ly con­tin­gent on his­to­ry. While one can try to con­struct an expla­na­tion for the supe­ri­or­i­ty of 5 fin­gers, pale­on­to­log­i­cal his­to­ry shows that there were poten­tial ances­tors of the tetra­pod clade (which we are part of) which had as many as eight rays per fin. If they had suc­ceed­ed, 8 fin­gers would be the norm, and the Simp­sons would look very odd with only 4. As Gould says of his­tor­i­cal con­tin­gency: “Oth­er con­fig­u­ra­tions would have worked and might have evolved, but they didn’t–and five works well enough.”

In the essay, Gould is build­ing on a point he made most force­ful­ly in an essay he wrote with Richard Lewon­tin, “The Span­drels of San Mar­cos and the Pan­gloss­ian Par­a­digm: A Cri­tique of the Adap­ta­tion­ist Pro­gram.” The point was that biol­o­gists were too quick to insist that every fea­ture was adap­tive and a result of nat­ur­al selec­tion. Span­drels are tri­an­gu­lar struc­tures pro­duced when two round arch­es meet. They are nec­es­sary byprod­ucts of join­ing round­ed and flat sur­faces. Nonethe­less, in many church­es they are rich­ly dec­o­rat­ed and the entire artis­tic vision for a space can be shaped by the span­drels. One might, Gould points out, be lead to think that the span­drels are there in order to be used for paint­ings, and not that they are nec­es­sary by-prod­ucts nice­ly dressed up. The world­view he crit­i­cizes treats any­thing, whether span­drels or five fin­gers, as the prod­uct of intense selec­tion, a per­fect solu­tion to the prob­lems it faces.

an old argu­ment holds that five [dig­its] might be an opti­mal con­fig­u­ra­tion for weight-bearing–a cen­tral axis cen­tered on dig­it three, with ade­quate and sym­met­ri­cal but­tress­ing on each side (one or three toes might not pro­vide enough lat­er­al sup­port against wob­bling, while sev­en toes might be super­flu­ous and inter­fere with loco­mo­tion). On this argu­ment, tetrapods have five toes because sup­port and loco­mo­tion demand (or at least strong­ly encour­age) this con­fig­u­ra­tion as optimal.

Gould com­pared this approach to that of Voltaire’s Doc­tor Pan­gloss, the court meta­physi­cian in Can­dide: or Opti­mism.

Mas­ter Pan­gloss taught the meta­physi­co-the­ol­o­go-cos­molonigol­o­gy. He could prove to admi­ra­tion that there is no effect with­out a cause; and, that in this best of all pos­si­ble worlds, the Baron’s cas­tle was the most mag­nif­i­cent of all cas­tles, and My Lady the best of all pos­si­ble baronesses.

“It is demon­stra­ble,” said he, “that things can­not be oth­er­wise than as they are; for as all things have been cre­at­ed for some end, they must nec­es­sar­i­ly be cre­at­ed for the best end. Observe, for instance, the nose is formed for spec­ta­cles, there­fore we wear spec­ta­cles. The legs are vis­i­bly designed for stock­ings, accord­ing­ly we wear stock­ings. Stones were made to be hewn and to con­struct cas­tles, there­fore My Lord has a mag­nif­i­cent cas­tle; for the great­est baron in the province ought to be the best lodged. Swine were intend­ed to be eat­en, there­fore we eat pork all the year round: and they, who assert that every­thing is right, do not express them­selves cor­rect­ly; they should say that every­thing is best.”

Lat­er, when the good Doc­tor has con­tract­ed syphilis, he says:

it was a thing unavoid­able, a nec­es­sary ingre­di­ent in the best of worlds; for if Colum­bus had not caught in an island in Amer­i­ca this dis­ease, which con­t­a­m­i­nates the source of gen­er­a­tion, and fre­quent­ly impedes prop­a­ga­tion itself, and is evi­dent­ly opposed to the great end of nature, we should have had nei­ther choco­late nor cochineal.

I raise this for two rea­sons. The same spir­it that moved Gould and Lewon­tin to decry this approach to the analy­sis of bio­log­i­cal sys­tems also moved peo­ple to crack down on “just-so sto­ries,” but to be clear about how a giv­en hypoth­e­sis about a struc­ture might be test­ed. The Index of Cre­ation­ist Claims explains more. Cre­ation­ists like to toss that word around now, but it was biol­o­gists who saw the prob­lem and have fixed it.

Fur­ther­more, mod­ern cre­ation­ism often takes on exact­ly this approach. The clas­sic exam­ple is Priv­i­leged Plan­et, the book and movie which the Dis­cov­ery Insti­tute has been push­ing as a case for Design in the Uni­verse. The book is, so far as I’ve been able to deter­mine, an extend­ed Pan­gloss­ian dia­tribe. Our moon is the best of all pos­si­ble moons because its posi­tion is just-so. Our solar sys­tem, our plan­et, our galaxy, the galax­ies around us, our atmos­phere, our eyes, our moun­tains, our orbit, our sun, all is for the best in this best of all pos­si­ble worlds.

The same approach creeps into cre­ation­ism in its ter­res­tri­al focus. We know Noah was able to fit all those ani­mals onto the ark because it was just-so. The rain­bow is evi­dence enough. The earth is 6,000 years old because that’s what you get when you add up all the gen­er­a­tions in the Bible, and all the avail­able sci­en­tif­ic evi­dence says oth­er­wise because things can­not be oth­er­wise than they are. The fla­gel­lum is a per­fect out­board motor, it can­not be oth­er­wise than as it is, for as it has been cre­at­ed for some end, it must nec­es­sar­i­ly be cre­at­ed for the best end (the rear end of a bac­teri­um). Humans, who sure­ly did not descend from pri­mates, can­not be oth­er than we are. And so forth. Of course, Dem­b­s­ki insists that intel­li­gent design need not be opti­mal design, but that’s a dodge. Con­sid­er the end of his essay from Feb­ru­ary, 2000:

This is a fall­en world. The good that God ini­tial­ly intend­ed is no longer ful­ly in evi­dence. Much has been per­vert­ed. Dys­tele­ol­o­gy, the per­ver­sion of design in nature, is a real­i­ty. It is evi­dent all around us. But how do we explain it? The sci­en­tif­ic nat­u­ral­ist explains dys­tele­ol­o­gy by claim­ing that the design in nature is only appar­ent, that it arose through muta­tion and nat­ur­al selec­tion (or some oth­er nat­ur­al mech­a­nism), and that imper­fec­tion, cru­el­ty, and waste are ful­ly to be expect­ed from such mech­a­nisms. But such mech­a­nisms can­not explain the com­plex, infor­ma­tion-rich struc­tures in nature that sig­nal actu­al and not mere­ly appar­ent design–that is, intel­li­gent design.

The design in nature is actu­al. More often than we would like, that design has got­ten per­vert­ed. But the per­ver­sion of design–dysteleology–is not explained by deny­ing design, but by accept­ing it and meet­ing the prob­lem of evil head on. The prob­lem of evil is a the­o­log­i­cal prob­lem. To force a res­o­lu­tion of the prob­lem by reduc­ing all design to appar­ent design is an eva­sion. It avoids both the sci­en­tif­ic chal­lenge posed by spec­i­fied com­plex­i­ty, and it avoids the hard work of faith, whose job is to dis­cern God’s hand in cre­ation despite the occlu­sions of evil.

The good that who ini­tial­ly intend­ed? I thought we did­n’t know who the Design­er is? Anyway.

The sci­en­tist does­n’t try to “explain dys­tele­ol­o­gy.” The sci­en­tist rec­og­nizes that issues of tele­ol­o­gy are for the­olo­gians to han­dle, and focus­es on the process­es which lead to a giv­en outcome.

IDol­a­tors want tele­ol­o­gy. They want 4.55 bil­lion years 6000 years 4.55 b 6000 his­to­ry to be inevitably lead­ing to them, right now. They want to live in a world where every­thing is best. Or at least could be, with­out those sci­en­tif­ic nat­u­ral­ists muck­ing things up.

Voltaire con­cludes his tale of Opti­mism with this passage:

In the neigh­bor­hood lived a famous dervish who passed for the best philoso­pher in Turkey; they went to con­sult him: Pan­gloss, who was their spokesman, addressed him thus:

“Mas­ter, we come to entreat you to tell us why so strange an ani­mal as man has been formed?”

“Why do you trou­ble your head about it?” said the dervish; “is it any busi­ness of yours?”

“But, Rev­erend Father,” said Can­dide, “there is a hor­ri­ble deal of evil on the earth.”

“What sig­ni­fies it,” said the dervish, “whether there is evil or good? When His High­ness sends a ship to Egypt does he trou­ble his head whether the rats in the ves­sel are at their ease or not?”

“What must then be done?” said Pangloss.

“Be silent,” answered the dervish.

“I flat­tered myself,” replied Pan­gloss, “to have rea­soned a lit­tle with you on the caus­es and effects, on the best of pos­si­ble worlds, the ori­gin of evil, the nature of the soul, and a pre-estab­lished harmony.”

At these words the dervish shut the door in their faces.

Adieu to the Pan­gloss­ian cre­ation­ists. There are more inter­est­ing ques­tions in the world than why low­er back pain is the most com­mon form of chron­ic pain. The human back is ver­ti­cal, all our ances­tors have hor­i­zon­tal ver­te­bral columns. How­ev­er opti­mal the curve of our spine, it is not how an engi­neer would build a ver­ti­cal sup­port. It’s exact­ly what you’d get if you took a lemur, stood it on two legs and did­n’t give it the good sense to lift with the knees, not with the back.

Inci­den­tal­ly, knees aren’t so well designed. Bipedal­ism is nov­el with­in mam­mals, and we haven’t worked all the kinks out. One could spec­u­late on the great ben­e­fits this brings to ortho­pe­dic sur­geons, but I’ll close the door on that ques­tion for now.