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Was Darwin Wrong?

DAVID QuAMMEN

E about life's volution work the by origin of natural Ch:ule> of adaptation. :.election, Darwin, lhe complexity. is ccnlral :o theory. concept and It's diversity a theory or the among Eanh's living creatures. If you arc skeptical by nature. unfamiliar will> the terminology of :,cience. and unaware of 1hc overwhelming evidence, you might even he tempted to <ay Ih at it's "just" a lheory. ln the >a me sense, relalivity as described by Albert Einslcin is 'just" :t theory. The notion that Earth orbits around the suo rather than vice versa, uflered by Copernicus in 1543, is a theory. Continental drifl is a 1hcory. The exi<~cncc.

suucrure. and dynamics or atoms? Aromic theory. C\'en elec tricity i> n theoretical con<truct. involving electrOns. which arc tiny units of charged mass that no one has ever seen. Each of these theories is an explanntion that bas been confinnNI tO such a degree. by observation and experiment. that knowledgeabk cxpen.< ~pi it a< fact. That's wbat scienth.ts mean when they talk about a theory: not a dreamy and unreliable speculation, but

an explanatory swtement that fits the evidence. They embrace

such an explanalion coniidcntly but provision~tlly-[aking it as 1heir best available view of reality, ar least umil M>Llle severely conflicting do1a "'some bener explanation mizht come alonr,.

Other people too. not just scriptural literalistS. remain UJlper suaclecl about evolutton. According to n Gallup pull drawn from more than a thousand telephone imerviews conducted in February 2001. no less th:m 45 percent of rcsponuiog U.S.

aduJts nj!TOOd that .. GOO created human bciogs preuy much in their present foml at one time within the last 10.000 years or so." Evolution. by their lights, played no role in shaping us.

Only 37 percent of the polled Amedcans were satislicd witll

allowing room for both God ~nd D~1rwln-that is, divine iuiLia

tive 10 get things staned. evolution a' lh~ creative means. (This

view. according to more than one papal pronounccmcnr, i.s com patible with Roman Catholic dogma.) Still fewer Americans, only 12 percent, believed that human> evolved from other life forms without any involvement of a god.

The most stanling thing about these poll numbers is not that so many Americans reject c'olutioo. but that the sU>tistical breakdown basn't changed much in two decades. Gallup inter viewet·s posed exactly the same choices in 1982. 1993, 1997,

and 1999. The creutionisr conviction-that God alone.. :.nd not

evolution. produced humans-bas never drawu les,; thun 44 per

little wall sockets, measure a y~;tr by the lenj!th of Earth's orbit. most.

Tbe rest of us gener.1lly agree. We plug our television, IntO und in many Olher ways Jiveou1'lives based on tJlc trusted rculily

of those theories.

Evolu!ionary lheory, tllough. is a bil <liffereot. It'• such a dangerously wonderful and far-reaching view of life tb;u -;(>me people lind it unacceptable. despite the vast body of supporting evidence. As applied to our own species, llo11w sapiens, it c:u1 seem more threatening stilL Many fundamentalist ChristiMs and ultra<>rthodox Jews take alarm at the thought that human descent from earlier primate' contradicts a strict reading of lhe Book of Gcnc.,is. Their discomfort is paralleled by Islamic cre atjonists such as Harun Yahy~ author of a recent volume ti1lc::d

Tire E•·olution Deceil, who points to tlle six-day creation story in ~ Koran as literal truth and calls the theory of evolution "nodling but a deception imposed on us by 1hc domina10<> ofthc world system." The late Sriln Prnbhupada. of the Hare Krishna movement, explained that God created "the 8.400,000 species of life frorn the very bcgilllling;· in order to establish multiple tiers of reincarnation for risin;; souls. Although souls ascend. !he ~·pecies 1hemselves don't change. he in•i>ted. di<mi<.,ing

"Datwin•s nonsensical theory:·

cent. In other word~, nc~ly half the American populnce prefers

to believe that Charle< Dm·,•in was "rong where it mattered ism c~n only be part of the answer. The American public cer·

Why W\: there .so many antievolutionist.s? ScripturnJ tiferal

ulinly iJICludes a large <cgment of <eripiUr.!lliterali,t<o-but not tltnr latj;c. not 44 percent Crearioni<t pro<elytizen. atld political activis~'· working hard to interfere with the teaching of evolu

tionary hiology in public school~. ~re another part. Honest <.:on

fusion and ignorance, among millions or aduJt Americans, must be \till anotber. Many people have never taken a biology course that dealt witll C\'Oiution nor read a hook in which the theo<y wa> lucidly explained. Sure. we ·,e all heard of Charlc> Darwin.

and ()fa vague. ~umber notion about ~truggle and survival that

sonlCtimcs goes by thcc:Hchall bbcl "Darwinism." 13ullhe main

sources ofinfom1arion rrum which mw.t Americans have drawn Lheir awa.rcm. ". SS or this subj«t. il 'CC:m~. arc h3ph:tzard qne...; at best: cultural osmo,is. newspaper and magazine rercreoces. half-baked nature documemaries on the tube, and hearsay.

Evolution is both u beautiful concept and an impo1an1 one. more crucial nowadays to human welfare. to medical 'cicncc. and to our understanding of tllc "orld than ever before. It's also deeply persuasive--a theory you c•m t.'lke ro the bank. Tbe

essential points are ~l ightly more cc.unp1icatcd than most people

aS<ome, but not so complicated that they can't be c(lmprchended

by any attenthre person. Furthcnnorc, the supporting evidence i~

abund::ml~ various, ever increasing, solidly interconnected, and easily available in museums, popular books, textbooks, and a mouncainous accumulation of peer-1·evicwcd scieotilic studies. No one needs to, and no one should. accept evolution merely as a matte!' of faith.

Two big ideas. not just one, are at issue: the evolution of all species, as a historical phenomenon, and natuml selection. as the main mechanism causing that phenomenon. The first is a question of what happened. TI1c second is a question of how. The idea that all species are descended from common ru1cestors had been suggested by other thinkers, including Jean-Baptiste Lamarck, long before Druwin t)Ublisbed The Origin (!( Species in 1859. Wbat made Darwin's book so remarkable when it

appeared, and so inllucntial in lhc long run, was lhm it offered a rational explanation of bow evolution must oectlr. The same insight came indcpcndc.ntly to Alfred Russel Wallace, a young naturalist doing field work in the Malay Archipelago during the late 1850s. In historical annals, if not in the popular awareness,

Wallace and Darwin ~h~trc the kudos for having discovered nat

ural selection.

The gisl o f the conce-pt is that small, nmdom, hcrit~tblc differ ences among individuals resu_lt in different chances of survival and rcproductio~succ.;cs~ for some, dc(tlh withoul uffsprl1.1g for others-and that thi::: muural cull ing leacts to s ignific.ant changes in sh~1pe, size, streng1h, :mnamcnt, color, hiochcrnis

try, and behavior muong the descend~nls. Excess p<>pulatinn growth drives the compelitive struggle. Becau~e Jess ~uccessfu I

competitors produce fewer surviving offspring, the useless or ucgative vru~ations tend to disappear. whereas the useful varia· tions tend to be perpetuated and gradually magnified throughout a population.

So much for one part of the evolutionary pl'(}(.'eSS. known as

anagenesis, during which a single species is transformed. But

there~s a lso a second part. known as speciation. Genetic changes somcLimcs accumulate within au isolatc:d segment or a species. but not d)rough.out tbe whole, as that isolated population adapl.s to its local conditions. Gradually it goes its own w~1y, seizing a new ecological niche. At a certain point it becomes iJTcvcrsibly

distind-that is, so different that its members can't interbreed with the rest. Two species now exist where formerly there was one. Darwin called that splining-and-specializing phenomenon the "principle of divergence.'' It was an importam part of his theory, explaining the overall diversity of life as well as the adaptation of individual species.

This thrilling and radical assemblage of concepts came from an unlikely source. Ch~1rh.::s O;.lf'\viu was shy (Uld ructkulous. <• wealthy landowner with close friends among t.hc Anglican clergy. He had a gentle, unassuJning manner, a strong ne-ed for p1ivacy, and <.)n excrnordinary comrniuncnt lO imcllcclUa1 honesty. As

an undergraduate at Cambridge, he b.ad studied halfheartedly toward becoming a c.;lcrgyu1om himself, befote he <.Jiscovered his reaJ vocation as a scientist. Later, having c~tabl ishcd u good but conventional reputation in natural history, he spent 22 years secre-tly gathering evidence and pondering argumcnts- tx>th

for ;md against his theory-because he dido 't wru1t to flame out in a burst of unpersuasive notoriety. He may have delayed,

too, bec.ause of h.is anxiety about announcing a theory that

seemed to challenge conventional religious beliefs-in particu lar, the Christian bclicls of his wife, Emma. Darwin himself quietly renounced Christianity during bis middle age, and later

descrjbed himself as an agnostic. He continued to beJievc in a distant, impersonal deiry of some $<ln., a greater entity that had set the universe and its laws into motion, but nOt in a personal God who had chosen humanity as a specially favored species.

Darwin avoided Jlaunting his lack of' religious faith, at least

partly in deference to Emma. And she prayed for his soul.

In l M5Y he tinally delivered his revolutionary book. Although

it was hefty and substantive at 490 pages, he considereU Tlu: Ori.r:in l.~f Species just a quick-and-dirty ;labstrac.;t'" of the huge volume he bad bc..---eu workit1g: on until interrupted by an alann.i.ng event. (fn fact, he'd wanted LO tit.lc iL An Abstract(~( an Essay

on the OJighr of Spl•cie.'>' and Varieties Through Nmural Sdt•c·

tion, but his publisher found Lhat insufficiently catchy.) The aJanning event was his receiving a leuer and an enclosed manu script ftom Alftcd Wallace, whom he knew only as a distant pen

pal. Wa11ace•s m~muscript :o;ketchcd out the ~unc great idea evolution hy natur~l selection-that O;lrwin considered his mvn. Wallace had s<:ribblcxl this paper m1<.l (unaware o l' IJarwin 's own evolutionary thinking, which ~o far had been kept private) mailed it tv h im from ~he r\:hJJ;;~y A1·chipelagv. a lo,lg wilh a requesL for re.lction ;md help. Darwin was holTified. After hv< .. dcc.ades of

painstaking cll'ort, now he'd be scooped. Or maybe nol quite. lie

forw~1rdL"d \VaJiacc•s paper toward puhlicalion, though rnanag ing nlso to assert hi~ own p rior c lttim by releasing t\VO excC1TJIS

from his unpublished work. '!'hen he dashed off the Origin. bis "abstract" on the subject. Unlike Wallace. who was younger and less meticulous, Darwin reco&rnized the impurtancc of provic.J

ing an edifice of supporting e\•idence and logic.

T he evidence~ ns he pre.-.:cntcd iL. most ly fell wilhin rour cate

gories: bivgcography, paleontology, emb•yology, and morpho!·

gy. Biogeography is I he swdy or the gcographicaJ di:)tributjou
f living creatures-that is. which species inhabit which parts
f the planet and why. Paleontology investigates extinct life- forms. a.<; n:ve;ded in the fossil record. Embryology examines the revealing stages of developm~nt (echoing earlier stages of evolutionary history) that embryos pass through before birth
r hatching: at a stretch, embryology also concerns the imma· ture forms of animals that metamorphose, such as the larvae
f itlSects. Morphology is the science of anatomical shape and design. Darwin devoted s izable sectio ns of The Origin of Species co these categories.

Biogeography, for instance, offered a great pageant of peculiar

facls aud paucrus. Anyone \VbO co.osiders the biogeog.rapbjcal data, Darwin wrote, must be Strock by the mystet"ioos cluster

ing pattern among what he called "closely allied" specics-th:H is, similru· creatures sharing roughly the same body p.lan. Such closely allied species tend to be found on the same continent (several spccic.s of zebras in Atiica} or within the same group of oceanic islru.1ds (dozens of species of honeycreepe"' in Hawaii,

13 species of Galapagos finch). despite their species-by-species

prcfctences for different habitats, food sources. or conditions of climate. Adjoetnt areas of South America, Darwin noted, nrc occupied by two similar spccic.s of large. flightlc.,s birds (the rheas. Rhefl tuncrimna and P1erocnemia pe!lnaUt), not by ostriches a.~ in Africa or emus as in Australia. South America also bas agouti\ and viscacbas (snull rodents) in terrestrial habi as Darwin tat<. plu.< coypu~ and capybaras in the well:mds. not wrote-bare;, and rabbit~ in terrc;trial habitats or beavers and m11s~T.lts in t.hc wetlands. During his own youthful visit to tbe Galiipagos, aboard the survey ship Beagle. Darwin himself had dbcovercd three very similar forms of mockingbird, each on a dill'etent island. Why should "closely allied" <pecic.s inhabit neighboring patches of habitat? And why should ;,tmitar habitat on different continents be occupied by species thnt aren't so c losely a ll ied? "We sec in thc.sc facts some deep oz·g~lnic hond. pz·cvniling throughout !\p~tcc and time:· Darwin wrote. "This bond. on my theory. is simply inheritance." Similar species occur nc:uby in <pocc bccau~ they have descended from common allCC!.tors. Paleontology reveals a similar clu;tering panem in the dimension of Lime. The venicul column of geologic Mnll;l, laid down by scdimcmary procC->>es over the eons, lightly peppered with fossils. represent~.; a langiblc r~.X:OI'll.'!-bOWiJlg which .species lived when. Le.~t; ancient layers of rock lie; a1op more ancient ones (ext-ept where geologic force' have lipped or • huffied them). and lil.cwbc: with the anim.tl IUld plii.Ot fos.'il ' that the strata CQntain. Whut Darwin noticccJ about this rc~.:ord j, that closely allied species tend to be found adjacent to one onolher in successive SU"Jla. One species endures for millions or years and then make.~ it~ last appearance in, say, the middle Eocene epocb: just above. a •iouilar but not identical specie' replaces it In North America. for example. a '"'guely horselike creature known as 1/ymrmhtn'tmJ was ~uccccdcd by OrollitJfJUS. then £pi1Jippus. then Mcsohippu.)·, which in tum were succ~d~.!d by a varieLy of horsey American crincr.-.. Some of them even gal· lopct.l acrw:-. the Bcdug land bridge into Asi~ [hen onwunlto Europe and Africa. Ay five million years ago they had nearly all dbappeare<l. lea' in!' behind Vit~olupplls, wbicb was SOJ<:<.'<:cded by Equus. the m"'lem genus ofhor<e. Not all these fo;sillinks had been uncart.l1ed in Darwi n's Uny. but he captured the essence o l' the matter ;myway. Again, were ~uch sequences ju~l t;Oin cideutal'/ No. Uatwi.J.J argued. Clo:.ely allied species <uccccd one anotber in time. a;, ""eU as living nearby in space. because they're related through evolutionary descent. Embryology 100 involved paltcm> that couldn ·, be explained by coincidence. Why docs the embo·yo or a mammal pass Lhrough stages resembling ~rages or the embryo o f a repli le'! Why is one of the larvrt.l forms of a barnacle:. before metamorphosis, M> ;imilar to the larv:U fonn of a 'hrimp? Why do the larv:oe of moths. flies. and beetles resemble one :wotber mott th.,n any of lhem resemble thctr respecti\-e adulh? Because, Darwin wrote. "tbc embryo is the unimal in its less modified stmc" and that stale "reveal' the strucLure of its progenitor." M01pbology. his founh categot')' of evidence, wa~ dle "very <oul" of natural history. according tO Darwin. Even today it's on display in tloe loyout and organit.otion of any 1.00. Here :ore the monkeys, there arc the big caL<. and in that building are the alligators ami <'nl<:odilcs. llirds in the aviary, fi>h in the

Article 2. Was Darwin Wrong?

aquarium. Living creatures can be easily soned into a hierar chy uf cutegories notjust species but genera, families, orders, who le kingdoms-based 0 11 which anatomical characte rs they ;,hare and which they don't.

All vcrtebr:ue animal< have backbone;. Among venebr:ues. birds ha\'C feather... whereas reptiles ha• c: ..:ales. Mammals have fur and mammary glands. D()( feathers or ;calc;,. Among mam mals. some have pnuches in which they nurxe their tiny young. Among these species, the marsupials, some have huge rear legs and 'tnJng tails by which ~1cy go hopping across miles of arid outback.: we <:<4lthem kangaroos. Bring in modem microscopic and molecular evidence. and you can rrnce the similaritie.~ still further back. All ptanh and fungi, as well a, animal>. have nuclei within their cells. AU living organisms contain DNA and RNA (ex.cept so me viru~c.:, wilh RNA on ly), two related form,-. of informatioo~oding molccuJcs.

groups of <imil:~r specie> nested within broader grouping<, and all descending from a single sourcc bn't naturally present among other col lections of items. Yuu won't find anything equivalent if you t.ry to c~ucgorizc rocks. or musicaJ instrumcnl~. or jewelry. Why nor! Because rock types and styles of jewelry don't reflect unhro~cn descent from common ance..~rors. Biological diversity doc~. The number of ~hared characteristics between any one ~ies and another indicates how recently 1hose two ~iC" have diverged from a ~hnrcd lineage.

Tha1 insight gave new meaning to the tnsk of wxonornic c las·

which had been founded in it> modem form back si flcation, in 1735 by the Swedish nat.W".tl.i.St Carolu~ Llnnaeu<. Linnaeu< showed how species could be systematically classified, 3CCOrd ing to tl1eir shared similarities, but he worked from creatinnist

Such a pattern of tiered resemblances

assumptions that ofTcn."(l no material cxplanatio11 for the nested p:Htern he found . ln the early and middle 19th century, morpholo

gist~ ~uch a~ George.-. Cuvier and Eaienne Geoffroy Saint-Hilaire

in Froncc :\nd Richard Owen io England improved clasl\ifica . tion with their metieulou< 'htdie.< of internal >S weU a.s external anatomies.. and tried 10 make sense or wh:n lhe ultimate SOtltee or these patterned similarities cou.ld be. Not even Owen. a con temporary and onetime friend of Darwin's (lat~r in Life they had a birtcr fal ling out). took the full step to an evolutionary v ision before The Origin r>fSperies wa.' published. Owen made a major mntribution. though, by advancing tbeconcept ofbomnloguc,,_ thai ;,, ;uperficially dill'erent but fundamentally similar ,..,rsions of a ;ingle organ or t.mit. shared by dissimilar species.

Fnr i nsl~wce. the fi\•e·digil skeletal ~true lUre of the vertebnuc hand appears nol just in humans and :.1pc.\ :md raccoon!) and l>et1N but a lso. variow:.ly modified. in curs and bats and ro•·.. poi\Cs and lizards and tunics.. The paired "")ncs of our lower kg, the tibia and the: libula. arc also rcp...,.,nted by bomologou.s

bone~ in other mammoh and in reptiles. anc.l e~-en in the long

xtin(t hirrl-o·eptilc Arf'lweopreryx. What's the reason behind such V(lried rccun·cnce of a le w basic designs? Darwin. with a uod to Owen's "mosr interesting work," supplied the answer: common de.o;cent, a.~ shaped by natural selection, modifying the inh<-ritcd basics for different circumstances.
1. .. tigial charactcrhtic~ an: slill anmhcr funn of morpholo~i
cal evidence, illuminaling to contemplate bccau~e rhey show

lhnt the living world is fuU of small, tolemblc imperfections. Why do male mammals (including human males) have nipples'! Why do some soakes (ootably boa consuictor<) corry the rudi· mcnt• of a pel vi• :and tiny legs buried inside their sleek profilc1.'1 Why do ccruin species of flightless beetle• have wing•. se:tled beneath wing cover.. that never open? Darwin rn•<cd all these questions. and aru.wered them. in Th• Origin of Sp.cin Ves ti,brial structures st3nd as remnants or the evolutionary hi~tory

of a lineage.

Today the same four branches of biological science from

which 0~1nVi11 drew-biogeography, paJCOntOfQgy, ClllbryoJ

ogy, morphology-embtace no ever growing body of suppott· ing data. In addition to those categories we now have others: population ~cnetics. hiochcmistry. molccul~tr hiology. and, rnos1 recen1 ly. the whiz-bang field of machine-driven gc.nc.tic ,;equcncing known a.< genomics. Tbese new forms of knowledge O\'etlap one another seamlessly and inter.<cct with the older forms, strengthening the whole edifice. contributing funher to the ccruinty lh:lt Darwin W:lS right. He wa• right ah<>ut evolution. that is. He wasn' t right about ~vuyrili11g. Being a restless explainer. Darwin Oooted 3 num· her of theoretical notion> during his long working life, some of which were mistAken and illusory. He wo.~;:, wrollg ~\bout what cau~~ vari:u ion within a species. He was wrong :.bout n f:unou."' geologic myMcry. lhe parallel shelves along a Scoui'h valley called Glen Roy. Most notably, his theory of inheritance-which he labeled pwlgcnc.,is and chetished despite its poor I'CCCplion amonl( his biologist colleagues-rumed out to be dead wmng. Fonunntcly J'o1' Darwin, the con·ectness or his most famou.' good idea stood indepcndenl nf thai particular bad idea. Evo lution by n:uura) sc)ccliOD n:presented l)ai'Win :n hi~ bc~twhich is IU ~ay. scientjfic observation and careful thinking al it< be\1. Douglas f'utuyma i• a highly respected evolution:lt)' biolo g.u"t. :lUiflOr or ICAIINV~ a." well as influential research p;.pcr":>. Hi< office, at the Univcl'l>ity of Michigan. is a long narrow room in the naturul ;cicnc:e,o, building, well stocked with journal~ and h<>o"-'. including volumes about the conllicl between creation ism ~uuJ evolution. I arrived CaJT);ng a well-thumbed copy vr his own book un that Mlbject. Scie11ct 011 Trio/: Tire Cau for E~·oiHiion. Killing time in the <..-onidor before our 8J)poimmcnt~ I noticed" blue llycr on a departmental buUetin boa,·d, seeming oddly placed (ht:r¢ ~mjd rhe announcements or carcc1· opportu· nit ics {Qr gr:.idualc students. ··creation vs. evolution." it S3id ...A seric..< (I)' messages challenging popular 1hough1 wilh DiblicaJ truth and -,cicntHic evidences.'· A traveling lecturer from \OOme· thing these """""$"' cu.lled the :1t Origins a local ReseMch Baptist chureh. Association Beside wnulc.J the lecturer'< (leliv~r photo wa~ o drawing of a din~ur. ~-Froe pi7.7..a following tbe .,,·ening ,.crvicc.'' s:ud 3 >mall line at the bottom. Dino'-'!urs. biblical lruth, and piu.a: something for everybody. In n:spon:.c to my questions about evidence, Dr. l'uruyma moved quickly through the traditional categories-p:llcontology. biogeogt:1phy-<~nd lalkcd mostly about modem ACnetics. He pulled out hi10 he:~.vily marked copy of the journal Nmun• for February 15,200 I, n historic issue, fa t wilh articles reponing nnd an~lly t.ing rhe re~ult!" of the Human Genome I •rojcct . Bc~idc: it he

slapped down a more re<".Cill is~ue of Nutu~. rhi~ one devoted ro the sequenced genome of the house mouse. Ml4s museu/ItS. The headline of the lead editorial announced: "HUMAN BIOLOGY

BY PROXY:· The lll()USC genome eff011, according to Nature's editors, had revealed "aboul 30.000 genes. with 99% having

direct counterpan.~ in human'\.~·

The resemblance between our 30,000 human genes and those 30.000 mousy counterpartS. l'utuyma explained, repre sents another form of homology. like the resemblance between a live-fingered hand and a live-toed paw. Such genetic homol·

ugy i~ what gives •ncaning to biomcc.JicoJ 1'csc.;1rch using mice and other ani mals, including chimpanzees, which (to their sad misfortune) are our closcsl living relatives.

No U..\-pcCt or biomedical r'C.\.Carch SCCrll\ more urgent today

than the s1udy of microbial disca.cs. And the dynamics of those microbes within human bodie". within human populations. can

only be understood in terms of e'•olution.

Nightmarish illnesses caused by microbes include both the infectious son (AIDS. Ebola. SARS) that spread directly from person to person and the son (malaria. We:;t Nile fever) deli•-ered to us by biting insect\ or ocher intcnnediarics. The

capacity for quick change :tmong <.l~aM:·causing microbes is what makes them so dangeroua. co large numbers of people and :so difticuh and cxpc:nsivt: lQ trent. They leap from wildlife or Jon1e:o:;tic animals into humans. adnpting co new circumstances

as they go. TI1eir inherent variability allow~ them to lind new

ways of evading aJld dcfcnrinn htumm immune systems. By

natural selection they acquite rcsiswnce to d rugs Lhat should kill them. They evolve. There's no bcllcr or ITlOrc immcdime evidence suppon:ing the Darwiniun Lhcory than this proces.~ of forced t.ransformatiou among our inimical germs.

Take the common bacterium Stopltylorocc-us auT?us. which

lurl;s in hospitals and eau""' .erious infections. especially among surgery patients. Penicillin. becoming available in 1943, pro•·ed almost mirnculou.sly cfl'ecli•e in fighting sl:lphylococ· cus infections. Its deploymenl m•rk•'<l a new pbase in the old war between humans 3nd disease nucrobes. a pbase in which

humans invent new killer dn1gs and microbes flnd new \'-"ilYS to be unlcillablc. The ~uprerne po1ency of penicillin didn'l la>t long. The first re.,istant strains of Slaphylococcu.< aureus were reported in 1947. A newer slaph-killing drug, methicillin. came into use during the 1960s. but n1cthicilli n-resistaut strains appeared soon, aod by the 198(],; 1hosc s~·nins were widesprea~. Vancomycin became Lhc next great wc.~pon against staph, ami the tirst vanoomycin-rcsistM I strain emerged in 2002. The.«:

antibiotic·rcs:istant SlrJins represent r.n evolutionary series, not

much different in principle from the fo~il .-,.eries tracing horse e\'Olution from Hyrticmheriwn to Eq11uJ. They make evolution a very prnctic.1l problem by adding cxpcnM:. as "eU as misery and danger. to the challenge of coping with >tapll.

1be biologist Stephen P:llnmhi h~s colculaled lhe cost of treating penicillin-n.-sistant and melhicillin-re.sistant staph infections. just in tbe United States. 3130 billion dollars a year. "Antibiotics exert a powerful evolutionary foree." he wrote la~t

year. ..d riving inf~ctious bacrcrin ro evolve powerfuJ defenses against all but tlte mosl reccnLiy iovcnt..:d OJ·ugs:· A~ reflected in tbelr DNA, which uses the same gcnc1ic code lhund in humans :md horses and hagfish and honeysuckle. bacteria are pan of the continuum of life. all shaped ;ond diversified by evolutionary

fO I'CCS.

quickly. some ~lowly. Amo1lg 1he fa."ttcst i~ HIV. bc..~ause its

Even viru~Cf; belong 10 that continuun1. Some viruses cvoJve

method or replicating itself involves a high rate of mutation. and !hose murarions allow the viru.> 10 assume new fomt>. Aflcr just a few years of infeclion and drug trca11nem, each HJV

p~ttien1 canie~ a unique vel':-oion of Lhe vinas. lsololiOn within one infected person. plus differing conditions and the struggle to survive. forc;e, each version or HIY to evolve independently. It's nOibing but a speeded up and microscopic ""'"' of wbat Darwin saw in the Galapagos-except that each human body is m1 island. and the newly evolved l'onns aren '1 so channing as tlocbes or mockingbirds. Umle.rstanding bow quickly lilY acquires resist anile to anti vita) drugs, such as AZT. bas been crucial 10 improving trcal mcnl by way of multiple drug cocktails. ~This approach has reduced deoth.< due 10 IUY by severalfold since 1996." a~-eording to Palurnbi. •·and jt has grcmly slowed Lhc cvolutioo of chis disease within p:.lticnts." Insects and weeds acquire rcsislance to our insecticides and herbicides through the same process. As we human.< try lo poison them. C\'Oiution by Mtur.tl selection transfonns the population of a mosqujto or thisrlc into :• new son of creature. le-.s ''tolnerablc to thai particular poison. So we invent tutother poison, then nnother. lt's a futileefl'<>o1. Even DDT, wi1 h it> fero cious and lcmg-lasling effects throu~hout ecosystems. produced re.._ist;rnt bou~ nics within a decade of its discO\·cry iu 1939. By 1990 more than 500 species (includmg 114 kinds of mos quitoes) bad ~uired resis~ance to nt least one pesticide. Based on these undesired resuhs, Stephen Pnlumbi has comrnenled glumly, ''humans 111ay be lhe wol'ld 's Uomina•lf evolutionary force.'• Among mosl lorm~ of living creature.~. evolution proc.ccd.s ;.lowly-100 slowly to be observed by a single scientist within a research tifetimc. But science functions by inference. not just by direct observntion, and the inferenlial w ns of evidence such as paleontology ;mel hiogcogl'aphy arc no less cogent si on ply because 1hcy'rc indirect. Still , skeptic.< of evolmionary lhcory :lJ;k: Can we~ evolution in acrion1 Can it be observed io the wild? Can it be measured in the labor.ttory? 111¢ answer i' yes. Peter nnd Ro.emary Gr.tnt. two British hom researchers who have spent d~"Cadcs where Charle.\ Darwin spent weeks, htovc CUI>tured a glimpse of evolution with their long-tenn studies of bc:lk size among Galapagos finches. William R. Rice and George W. Suit achieved something simi lar in their lab. thn>ugh an experiment io,•olving 35 generations of lhc fruit fly Drosophila mrltmoflu>ler. Richard E. l.cn,ki and his colleagues at Michigan Stale Urtiversity have done it too, tracking 20.000 generation' of evolution in the bac1crium Escherichia l'(j/i, Such tield sLudics and lab experiments docu ment anages\e~i~LhaL is. ~low evolutionary chang..: withi n a >ingle. unsplit lineage. \\r,th patience il can be seen, like thc nw,-ement of n minute band on a clock. Speciation, when a lineage splitS into IWO specie>. i> the other major phase of evolutionary change, mak.inA possible the

Artic le 2 . Was Da rwin Wrong? divergence between lineages about whicb D<trwin wrote. It's

rarer untl more elusive even than anagcncsi~. Many individual mutations must accu111ulalc (in mosl ce~ses. a.nyway. with cer

tain excepdOilS ~Lmong planL~) bcJOre two popt•lations beconle itrevocabldy sepamted. The process is spread :ocros.< 1hou..and.' of generations. yet it may finish abruptly-like a door going slam!-when the last critical changes occur. Therefore it's much harder to witness. Dcspile !he difficu hies, Rice and Sail S<.~m to have rect>rdcd n speciation event, or very nearly so, in their cx1cndcd cxperimem on f111i1 fl ies. Frorn u small stock or ma1ed female.' thcy eventually produced IWO di\linct fly populalion> ad;tpted 10 different hnbit01 condilioo<. which tbe researcher..

judged "incipient species:·

Afterrnyvisit with Douglas f utuymn inAnnArtmr, hpent two hours llt the university llluseum there with Philip D. Gingerich. a paleontologist well-known for his work on the ancesuy of whal~. As we talkec.l. Gingerich guided me through an exhibit

f ancieol ce1aceon' on the museum'< scx:ond fl()()(. Amid weird <keletal $hap<-"' that seemed almost chimerical (some hangin~
vcrhe~d. some in gla~' cases) he pointed out significnnt rca· tuo·cn and described Ih e progre.<s of thinking alx>ul whale evolu- lion. A burly man with a hmad open face and the gentle manner
f a o;c<>ulnlaster. Ginecrich combines intcllccrual pas<ion and solid expertise wilh one odler trait that's ,aJunble in a scienli>t: a willingnes.' to :~!mil when he's wrong.
- Since the late 1970, Gingerich ha.~ collecled fossil >pcci-
rncns of early whnlcs f1·on1 remote digs in l}gypt and PakisU.u1. WOI';king Wilh Pakisutni colleague~. he discovered Pukicrtus. u terre~Lrial mammal duting rrom 50 million years ago. who:-.ccar bones rcOect its membership in the whllle lineage bul whose skull looks almost doglike. A former student of Gingerich's,

Hans Thcwissen. fuund a slightly more recent form with

webbed feet. legs suitabl&: for either walkin~

or swinuning, and

a lon~ tOOthy snout. ·n,cwissen called it Ambulocews 1w twa.\,

ur the ''walking·tuld-swimming whulc.'' Qjn_gerich and his tcum rumed up sever.:tl more. induding Rodhoa:ws bn/(}(-h

i.~ltlllt'IIJis, which was fully :a se-a creature. its legs more like

Oippc". ib nostrils shined backward on the snout, h:llfway to the blowhole position on a modern whale. The sc<1ucnce

all alOll£. Gingerich tuld me, he leaned Inward believing thm whale.• had descended from ~ group or carnivorous Eocene mammals known a< mcsonychids. wi1h check teem useful for

of known forms w~1s becoming more :md more complete. And chewing meat and bone. Just a bit more evidence, he lhoughl.

would confirm that rcltotionsbip. Ry the end of the 1990s mo'r palconlologists agreed.

Meanwhile. molecular biologiSis 1\(ld explored the same que>tion and arri"cd lll a different an~wer. No. the match to those Eocene camh'Orc;. might be clO<;e. but not close enough. DNA hybridization nnd nther t<!Sb >uggestcd that whale' had dc<eended from aniodactyls (that i>. even-toed hert>i\'orcs, 'uch a.~ nnlclopus and hippos). not from mc<.~ l -cating mesonychi<.Js.

In the ycar2000 Gin~;crich chose a new field site in Puki>lan. where one of hi' \ tutlellls found a single piece of fossil that chang•-d the prevailing view in paleontology. ll was half of a pulley-shaped anklebone. known 3$ an nw:ogalu>. belonging to

another new species or whale.

A Pakistani colleague found the fragment's other half. When Gingerich fi lled the two pieces together, he had a moment of humbling recognition: The molecular biologistS were right.

Here wa.~ al) a1lklebone, from a four .. fcgged whale daring back 47million years, !hat closely resembled the homologus ani<Je bone in an artiodactyl. Suddenly he realized how closely whales

are relat~d lO antelopes.

This is how science is supposed to work. Ideas come and go. bur the finest survive. Downstairs in bis office Phil Gingerich opened a specimen drawer. showing me some of !he actual fossils from which the display skeletons upstairs were modeled. He put a smaU lump of petrified bone, no longer than a lug nut, into my hand. It was the famous astragalus, from the species he had even. .

tually named Aniocer.us clavis. It felt solid and heavy as truth.

Seeing roe 10 the door, Gingerich volunteered something

pc.;rsonal: ul grew up in a COilservatjve ChlU'Ch iJl lhe Ntidwest

and was uot taughl <l.Oydling about e\•oJutiorl. The ~ubjecr wa.s

clearly skirted. That helps me undcrstanu the people wbo are skeptical about it. Because I come from that tradition myself." He share.~ the same skeptical instinct. Tell him that there's an

ancesual conn<:CLion bel ween land animals and whale.~~ and

his reaction is: Fine. maybe. But show me the intermediate stages. Like Charles Darwin, the onetime divinity student, who joined that round-the-world voyage aboard d1e Beagle instead of becoming a counny parson, and whose grand view of life on Earth was shaped by attention to small facts, Phil Gingerich is a reverant empiricist. He ·s not satisfied until he sees solid data. That's wb.at excites him so much about pulling shale fossils out of the b'TOund. In 30 years he has seen enough to be satisfied. For tUm. Gingerich said, it's ·'a spiritual experience." '"fhe evidence is there;• he added. "lt's buried in the rocks

of ages."