A Short History of Nearly Everything-第71章

按键盘上方向键 ← 或 → 可快速上下翻页，按键盘上的 Enter 键可回到本书目录页，按键盘上方向键 ↑ 可回到本页顶部！
————未阅读完？加入书签已便下次继续阅读！


has　described　them　as　“soft…bodiedoddities。”

there　is　still　very　little　agreement　about　what　these　things　were　or　how　they　lived。　theyhad；　as　far　as　can　be　told；　no　mouth　or　anus　with　which　to　take　in　and　discharge　digestivematerials；　and　no　internal　organs　with　which　to　process　them　along　the　way。　“in　life；”　forteysays；　“most　of　them　probably　simply　lay　upon　the　surface　of　the　sandy　sediment；　like　soft；structureless　and　inanimate　flatfish。”　at　their　liveliest；　they　were　no　more　plex　thanjellyfish。　all　the　ediacaran　creatures　were　diploblastic；　meaning　they　were　built　from　twolayers　of　tissue。　with　the　exception　of　jellyfish；　all　animals　today　are　triploblastic。

some　experts　think　they　weren’t　animals　at　all；　but　more　like　plants　or　fungi。　thedistinctions　between　plant　and　animal　are　not　always　clear　even　now。　the　modern　spongespends　its　life　fixed　to　a　single　spot　and　has　no　eyes　or　brain　or　beating　heart；　and　yet　is　ananimal。　“when　we　go　back　to　the　precambrian　the　differences　between　plants　and　animalswere　probably　even　less　clear；”　says　fortey。　“there　isn’t　any　rule　that　says　you　have　to　bedemonstrably　one　or　the　other。”

nor　is　it　agreed　that　the　ediacaran　organisms　are　in　any　way　ancestral　to　anything　alivetoday　（except　possibly　some　jellyfish）。　many　authorities　see　them　as　a　kind　of　failedexperiment；　a　stab　at　plexity　that　didn’t　take；　possibly　because　the　sluggish　ediacaranorganisms　were　devoured　or　outpeted　by　the　lither　and　more　sophisticated　animals　of　thecambrian　period。

“there　is　nothing　closely　similar　alive　today；”　fortey　has　written。　“they　are　difficult　tointerpret　as　any　kind　of　ancestors　of　what　was　to　follow。”

the　feeling　was　that　ultimately　they　weren’t　terribly　important　to　the　development　of　lifeon　earth。　many　authorities　believe　that　there　was　a　mass　extermination　at　the　precambrian–cambrian　boundary　and　that　all　the　ediacaran　creatures　（except　the　uncertain　jellyfish）　failedto　move　on　to　the　next　phase。　the　real　business　of　plex　life；　in　other　words；　started　withthe　cambrian　explosion。　that’s　how　gould　saw　it　in　any　case。

as　for　the　revisions　of　the　burgess　shale　fossils；　almost　at　once　people　began　to　questionthe　interpretations　and；　in　particular；　gould’s　interpretation　of　the　interpretations。　“from　thefirst　there　were　a　number　of　scientists　who　doubted　the　account　that　steve　gould　hadpresented；　however　much　they　admired　the　manner　of　its　delivery；”　fortey　wrote　in　life。　thatis　putting　it　mildly。

“if　only　stephen　gould　could　think　as　clearly　as　he　writes！”　barked　the　oxford　academicrichard　dawkins　in　the　opening　line　of　a　review　（in　the　london　sunday　telegraph）　ofwonderful　life。　dawkins　acknowledged　that　the　book　was　“unputdownable”　and　a　“literarytour…de…force；”　but　accused　gould　of　engaging　in　a　“grandiloquent　and　near…disingenuous”

misrepresentation　of　the　facts　by　suggesting　that　the　burgess　revisions　had　stunned　thepaleontological　munity。　“the　view　that　he　is　attacking—that　evolution　marchesinexorably　toward　a　pinnacle　such　as　man—has　not　been　believed　for　50　years；”　dawkinsfumed。

and　yet　that　was　exactly　the　conclusion　to　which　many　general　reviewers　were　drawn。

one；　writing　in　the　new　york　times　book　review；　cheerfully　suggested　that　as　a　result　ofgould’s　book　scientists　“have　been　throwing　out　some　preconceptions　that　they　had　notexamined　for　generations。　they　are；　reluctantly　or　enthusiastically；　accepting　the　idea　thathumans　are　as　much　an　accident　of　nature　as　a　product　of　orderly　development。”

but　the　real　heat　directed　at　gould　arose　from　the　belief　that　many　of　his　conclusions　weresimply　mistaken　or　carelessly　inflated。　writing　in　the　journal　evolution；　dawkins　attackedgould’s　assertions　that　“evolution　in　the　cambrian　was　a　different　kind　of　process　fromtoday”　and　expressed　exasperation　at　gould’s　repeated　suggestions　that　“the　cambrian　was　aperiod　of　evolutionary　‘experiment；’　evolutionary　‘trial　and　error；’　evolutionary　‘false　starts。’　。

。　。　it　was　the　fertile　time　when　all　the　great　‘fundamental　body　plans’　were　invented。

nowadays；　evolution　just　tinkers　with　old　body　plans。　back　in　the　cambrian；　new　phyla　andnew　classes　arose。　nowadays　we　only　get　new　species！”

noting　how　often　this　idea—that　there　are　no　new　body　plans—is　picked　up；　dawkins　says：

“it　is　as　though　a　gardener　looked　at　an　oak　tree　and　remarked；　wonderingly：　‘isn’t　it　strangethat　no　major　new　boughs　have　appeared　on　this　tree　for　many　years？　these　days；　all　the　newgrowth　appears　to　be　at　the　twig　level。’　”

“it　was　a　strange　time；”　fortey　says　now；　“especially　when　you　reflected　that　this　was　allabout　something　that　happened　five　hundred　million　years　ago；　but　feelings　really　did　runquite　high。　i　joked　in　one　of　my　books　that　i　felt　as　if　i　ought　to　put　a　safety　helmet　on　beforewriting　about　the　cambrian　period；　but　it　did　actually　feel　a　bit　like　that。”

strangest　of　all　was　the　response　of　one　of　the　heroes　of　wonderful　life；　simon　conwaymorris；　who　startled　many　in　the　paleontological　munity　by　rounding　abruptly　on　gouldin　a　book　of　his　own；　the　crucible　of　creation。　the　book　treated　gould　“with　contempt；　evenloathing；”　in　fortey’s　words。　“i　have　never　encountered　such　spleen　in　a　book　by　aprofessional；”　fortey　wrote　later。　“the　casual　reader　of　the　crucible　of　creation；　unaware　ofthe　history；　would　never　gather　that　the　author’s　views　had　once　been　close　to　（if　not　actuallyshared　with）　gould’s。”

when　i　asked　fortey　about　it；　he　said：　“well；　it　was　very　strange；　quite　shocking　really；because　gould’s　portrayal　of　him　had　been　so　flattering。　i　could　only　assume　that　simon　wasembarrassed。　you　know；　science　changes　but　books　are　permanent；　and　i　suppose　he　regrettedbeing　so　irremediably　associated　with　views　that　he　no　longer　altogether　held。　there　was　allthat　stuff　about　‘oh　fuck；　another　phylum’　and　i　expect　he　regretted　being　famous　for　that。”

what　happened　was　that　the　early　cambrian　fossils　began　to　undergo　a　period　of　criticalreappraisal。　fortey　and　derek　briggs—one　of　the　other　principals　in　gould’s　book—used　amethod　known　as　cladistics　to　pare　the　various　burgess　fossils。　in　simple　terms；　cladisticsconsists　of　organizing　organisms　on　the　basis　of　shared　features。　fortey　gives　as　an　examplethe　idea　of　paring　a　shrew　and　an　elephant。　if　you　considered　the　elephant’s　large　size　andstriking　trunk　you　might　conclude　that　it　could　have　little　in　mon　with　a　tiny；　sniffingshrew。　but　if　you　pared　both　of　them　with　a　lizard；　you　would　see　that　the　elephant　andshrew　were　in　fact　built　to　much　the　same　plan。　in　essence；　what　fortey　is　saying　is　thatgould　saw　elephants　and　shrews　where　they　saw　mammals。　the　burgess　creatures；　theybelieved；　weren’t　as　strange　and　various　as　they　appeared　at　first　sight。　“they　were　often　nostranger　than　trilobites；”　fortey　says　now。　“it　is　just　that　we　have　had　a　century　or　so　to　getused　to　trilobites。　familiarity；　you　know；　breeds　familiarity。”

this　wasn’t；　i　should　note；　because　of　sloppiness　or　inattention。　interpreting　the　forms　andrelationships　of　ancient　animals　on　the　basis　of　often　distorted　and　fragmentary　evidence　isclearly　a　tricky　business。　edward　o。　wilson　has　noted　that　if　you　took　selected　species　ofmodern　insects　and　presented　them　as　burgess…style　fossils　nobody　would　ever　guess　that　theywere　all　from　the　same　phylum；　so　different　are　their　body　plans。　also　instrumental　in　helpingrevisions　were　the　discoveries　of　two　further　early　cambrian　sites；　one　in　greenland　and　onein　china；　plus　more　scattered　finds；　which　between　them　yielded　many　additional　and　oftenbetter　specimens。

the　upshot　is　that　the　burgess　fossils　were　found　to　be　not　so　different　after　all。

hallucigenia；　it　turned　out；　had　been　reconstructed　upside　down。　its　stilt…like　legs　wereactually　spikes　along　its　back。　peytoia；　the　weird　creature　that　looked　like　a　pineapple　slice；was　found　to　be　not　a　distinct　creature　but　merely　part　of　a　larger　animal　called　anomalocaris。

many　of　the　burgess　specimens　have　now　been　assigned　to　living　phyla—just　where　walcottput　them　in　the　first　place。　hallucigenia　and　some　others　are　thought　to　be　related　toonychophora；　a　group　of　caterpillar…like　animals。　others　have　been　reclassified　as　precursorsof　the　modern　annelids。　in　fact；　says　fortey；　“there　are　relatively　few　cambrian　designs　thatare　wholly　novel。　more　often　they　turn　out　to　be　just　interesting　elaborations　of　well…established　designs。”　as　he　wrote　in　his　book　life：　“none　was　as　strange　as　a　present　daybarnacle；　nor　as　grotesque　as　a　queen　termite。”

so　the　burgess　shale　specimens　weren’t　so　spectacular　after　all。　this　made　them；　as　forteyhas　written；　“no　less　interesting；　or　odd；　just　more　explicable。”　their　weird　body　plans　werejust　a　kind　of　youthful　exuberance—the　evolutionary　equivalent；　as　it　were；　of　spiked　hair　andtongue　studs。　eventually　the　forms　settled　into　a　staid　and　stable　middle　age。

but　that　still　left　the　enduring　question　of　where　all　these　animals　had　e　from—howthey　had　suddenly　appeared　from　out　of　nowhere。

alas；　it　turns　out　the　cambrian　explosion　may　not　have　been　quite　so　explosive　as　all　that。

the　cambrian　animals；　it　is　now　thought；　we