万物简史英文版_比尔·布莱森-第66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！


e　soon　after。

clearly　it　helped　to　be　at　home　in　water。　the　kt　impact　wiped　out　almost　90　percent　ofland…based　species　but　only　10　percent　of　those　living　in　fresh　water。　water　obviously　offeredprotection　against　heat　and　flame；　but　also　presumably　provided　more　sustenance　in　the　leanperiod　that　followed。　all　the　land…based　animals　that　survived　had　a　habit　of　retreating　to　asafer　environment　during　times　of　danger鈥攊nto　water　or　underground鈥攅ither　of　whichwould　have　provided　considerable　shelter　against　the　ravages　without。　animals　thatscavenged　for　a　living　would　also　have　enjoyed　an　advantage。　lizards　were；　and　are；　largelyimpervious　to　the　bacteria　in　rotting　carcasses。　indeed；　often　they　are　positively　drawn　to　it；and　for　a　long　while　there　were　clearly　a　lot　of　putrid　carcasses　about。

it　is　often　wrongly　stated　that　only　small　animals　survived　the　kt　event。　in　fact；　among　thesurvivors　were　crocodiles；　which　were　not　just　large　but　three　times　larger　than　they　are　today。

but　on　the　whole；　it　is　true；　most　of　the　survivors　were　small　and　furtive。　indeed；　with　theworld　dark　and　hostile；　it　was　a　perfect　time　to　be　small；　warm…blooded；　nocturnal；　flexible　indiet；　and　cautious　by　nature鈥攖he　very　qualities　that　distinguished　our　mammalian　forebears。

had　our　evolution　been　more　advanced；　we　would　probably　have　been　wiped　out。　instead；mammals　found　themselves　in　a　world　to　which　they　were　as　well　suited　as　anything　alive。

however；　it　wasn鈥檛　as　if　mammals　swarmed　forward　to　fill　every　niche。　鈥渆volution　mayabhor　a　vacuum；鈥潯�wrote　the　paleobiologist　steven　m。　stanley；　鈥渂ut　it　often　takes　a　long　timeto　fill　it。鈥潯�for　perhaps　as　many　as　ten　million　years　mammals　remained　cautiously　small。　inthe　early　tertiary；　if　you　were　the　size　of　a　bobcat　you　could　be　king。

but　once　they　got　going；　mammals　expanded　prodigiously鈥攕ometimes　to　an　almostpreposterous　degree。　for　a　time；　there　were　guinea　pigs　the　size　of　rhinos　and　rhinos　the　sizeof　a　two…story　house。　wherever　there　was　a　vacancy　in　the　predatory　chain；　mammals　rose（often　literally）　to　fill　it。　early　members　of　the　raccoon　family　migrated　to　south　america；discovered　a　vacancy；　and　evolved　into　creatures　the　size　and　ferocity　of　bears。　birds；　too；prospered　disproportionately。　for　millions　of　years；　a　gigantic；　flightless；　carnivorous　birdcalled　titanis　was　possibly　the　most　ferocious　creature　in　north　america。　certainly　it　was　themost　daunting　bird　that　ever　lived。　it　stood　ten　feet　high；　weighed　over　eight　hundred　pounds；and　had　a　beak　that　could　tear　the　head　off　pretty　much　anything　that　irked　it。　its　familysurvived　in　formidable　fashion　for　fifty　million　years；　yet　until　a　skeleton　was　discovered　inflorida　in　1963；　we　had　no　idea　that　it　had　ever　existed。

which　brings　us　to　another　reason　for　our　uncertainty　about　extinctions：　the　paltriness　ofthe　fossil　record。　we　have　touched　already　on　the　unlikelihood　of　any　set　of　bones　beingfossilized；　but　the　record　is　actually　worse　than　you　might　think。　consider　dinosaurs。

museums　give　the　impression　that　we　have　a　global　abundance　of　dinosaur　fossils。　in　fact；overwhelmingly　museum　displays　are　artificial。　the　giant　diplodocus　that　dominates　theentrance　hall　of　the　natural　history　museum　in　london　and　has　delighted　and　informedgenerations　of　visitors　is　made　of　plaster鈥攂uilt　in　1903　in　pittsburgh　and　presented　to　themuseum　by　andrew　carnegie。　the　entrance　hall　of　the　american　museum　of　natural　historyin　new　york　is　dominated　by　an　even　grander　tableau：　a　skeleton　of　a　large　barosaurusdefending　her　baby　from　attack　by　a　darting　and　toothy　allosaurus。　it　is　a　wonderfullyimpressive　display鈥攖he　barosaurus　rises　perhaps　thirty　feet　toward　the　high　ceiling鈥攂ut　alsoentirely　fake。　every　one　of　the　several　hundred　bones　in　the　display　is　a　cast。　visit　almost　anylarge　natural　history　museum　in　the　world鈥攊n　paris；　vienna；　frankfurt；　buenos　aires；mexico　city鈥攁nd　what　will　greet　you　are　antique　models；　not　ancient　bones。

the　fact　is；　we　don鈥檛　really　know　a　great　deal　about　the　dinosaurs。　for　the　whole　of　the　ageof　dinosaurs；　fewer　than　a　thousand　species　have　been　identified　（almost　half　of　them　knownfrom　a　single　specimen）；　which　is　about　a　quarter　of　the　number　of　mammal　species　alivenow。　dinosaurs；　bear　in　mind；　ruled　the　earth　for　roughly　three　times　as　long　as　mammalshave；　so　either　dinosaurs　were　remarkably　unproductive　of　species　or　we　have　barelyscratched　the　surface　（to　use　an　irresistibly　apt　clich茅）。

for　millions　of　years　through　the　age　of　dinosaurs　not　a　single　fossil　has　yet　been　found。

even　for　the　period　of　the　late　cretaceous鈥攖he　most　studied　prehistoric　period　there　is；thanks　to　our　long　interest　in　dinosaurs　and　their　extinction鈥攕ome　three　quarters　of　allspecies　that　lived　may　yet　be　undiscovered。　animals　bulkier　than　the　diplodocus　or　moreforbidding　than　tyrannosaurus　may　have　roamed　the　earth　in　the　thousands；　and　we　maynever　know　it。　until　very　recently　everything　known　about　the　dinosaurs　of　this　period　camefrom　only　about　three　hundred　specimens　representing　just　sixteen　species。　the　scantiness　ofthe　record　led　to　the　widespread　belief　that　dinosaurs　were　on　their　way　out　already　when　thekt　impact　occurred。

in　the　late　1980s　a　paleontologist　from　the　milwaukee　public　museum；　peter　sheehan；decided　to　conduct　an　experiment。　using　two　hundred　volunteers；　he　made　a　painstakingcensus　of　a　well…defined；　but　also　well…picked…over；　area　of　the　famous　hell　creek　formationin　montana。　sifting　meticulously；　the　volunteers　collected　every　last　tooth　and　vertebra　andchip　of　bone鈥攅verything　that　had　been　overlooked　by　previous　diggers。　the　work　took　threeyears。　when　finished　they　found　that　they　had　more　than　tripled　the　global　total　of　dinosaurfossils　from　the　late　cretaceous。　the　survey　established　that　dinosaurs　remained　numerousright　up　to　the　time　of　the　kt　impact。　鈥渢here　is　no　reason　to　believe　that　the　dinosaurs　weredying　out　gradually　during　the　last　three　million　years　of　the　cretaceous；鈥潯�sheehan　reported。

we　are　so　used　to　the　notion　of　our　own　inevitability　as　life鈥檚　dominant　species　that　it　ishard　to　grasp　that　we　are　here　only　because　of　timely　extraterrestrial　bangs　and　other　randomflukes。　the　one　thing　we　have　in　mon　with　all　other　living　things　is　that　for　nearly　fourbillion　years　our　ancestors　have　managed　to　slip　through　a　series　of　closing　doors　every　timewe　needed　them　to。　stephen　jay　gould　expressed　it　succinctly　in　a　well…known　line：　鈥渉umansare　here　today　because　our　particular　line　never　fractured鈥攏ever　once　at　any　of　the　billionpoints　that　could　have　erased　us　from　history。鈥�

we　started　this　chapter　with　three　points：　life　wants　to　be；　life　doesn鈥檛　always　want　to　bemuch；　life　from　time　to　time　goes　extinct。　to　this　we　may　add　a　fourth：　life　goes　on。　andoften；　as　we　shall　see；　it　goes　on　in　ways　that　are　decidedly　amazing。

ww锛枫��



23　　　　THE　RICHNESS　OF　BEING

灏�*璇�**t*xt**澶�*鍫�
here　and　there　in　the　natural　history　museum　in　london；　built　into　recesses　along　theunderlit　corridors　or　standing　between　glass　cases　of　minerals　and　ostrich　eggs　and　a　centuryor　so　of　other　productive　clutter；　are　secret　doors鈥攁t　least　secret　in　the　sense　that　there　isnothing　about　them　to　attract　the　visitor鈥檚　notice。　occasionally　you　might　see　someone　withthe　distracted　manner　and　interestingly　willful　hair　that　mark　the　scholar　emerge　from　one　ofthe　doors　and　hasten　down　a　corridor；　probably　to　disappear　through　another　door　a　littlefurther　on；　but　this　is　a　relatively　rare　event。　for　the　most　part　the　doors　stay　shut；　giving　nohint　that　beyond　them　exists　another鈥攁　parallel鈥攏atural　history　museum　as　vast　as；　and　inmany　ways　more　wonderful　than；　the　one　the　public　knows　and　adores。

the　natural　history　museum　contains　some　seventy　million　objects　from　every　realm　oflife　and　every　corner　of　the　planet；　with　another　hundred　thousand　or　so　added　to　thecollection　each　year；　but　it　is　really　only　behind　the　scenes　that　you　get　a　sense　of　what　atreasure　house　this　is。　in　cupboards　and　cabinets　and　long　rooms　full　of　close…packed　shelvesare　kept　tens　of　thousands　of　pickled　animals　in　bottles；　millions　of　insects　pinned　to　squaresof　card；　drawers　of　shiny　mollusks；　bones　of　dinosaurs；　skulls　of　early　humans；　endlessfolders　of　neatly　pressed　plants。　it　is　a　little　like　wandering　through　darwin鈥檚　brain。　the　spiritroom　alone　holds　fifteen　miles　of　shelving　containing　jar　upon　jar　of　animals　preserved　inmethylated　spirit。

back　here　are　specimens　collected　by　joseph　banks　in　australia；　alexander　von　humboldtin　amazonia；　darwin　on　the　beagle　voyage；　and　much　else　that　is　either　very　rare　orhistorically　important　or　both。　many　people　would　love　to　get　their　hands　on　these　things。　afew　actually　have。　in　1954　the　museum　acquired　an　outstanding　ornithological　collection　fromthe　estate　of　a　devoted　collector　named　richard　meinertzhagen；　author　of　birds　of　arabia；among　other　scholarly　works。　meinertzhagen　had　been　a　faithful　attendee　of　the　museum　foryears；　ing　almost　daily　to　take　notes　for　the　production　of　his　books　and　monographs。

when　the　crates　arrived；　the　curators　excitedly　jimmied　them　open　to　see　what　they　had　beenleft　and　were　surprised；　to　put　it　mildly；　to　discover　that　a　very　large　number　of　specimensbore　the　museum鈥檚　own　labels。　mr。　meinertzhagen；　it　turned　out；　had　been　helping　himself　totheir　collections　for　years。　it　also　explained　his　habit　of　wearing　a　large　overcoat　even　duringwarm　weather。

a　few　years　later　a　charming　old　regular　in　the　mollusks　department鈥斺�渜uite　a　distinguishedgentleman；鈥潯�i　was　told鈥攚as　caught　inserting　valued　seashells　into　the　hollow　legs　of　hiszimmer　frame。

鈥渋　don鈥檛　suppose　there鈥檚　anything　in　here　that　somebody　somewhere　doesn鈥檛　covet；鈥�

richard　fortey　said　with　a　thoughtful　air　as　he　gave　me　a　tour　of　the　beguiling　world　that　isthe　behind…the…scenes　part　of　the　museum。　we　wandered　through　a　confusion　of　departmentswhere　people　sat　at　large　tables　doing　intent；　investigative　things　with　arthropods　and　palmfronds　and　boxes　of　yellowed　bones。　everywhere　there　was　an　air　of　unhurried　thoroughness；of　people　being　engaged　in　a　gigantic　endeavor　that　could　never　be　pleted　and　mustn鈥檛　berushed。　in　1967；　i　had　read；　the　museum　issued　its　report　on　the　john　murray　expedition；　anindian　ocean　survey；　forty…four　years　after　the　expedition　had　concluded。　this　is　a　worldwhere　things　move　at　their　own　pace；　including　a　tiny　lift　fortey　and　i　shared　with　a　scholarlylooking　elderly　man　with　whom　fortey　chatted　genially　and　familiarly　as　we　proceededupwards　at　about　the　rate　that　sediments　are　laid　down。

when　the　man　departed；　fortey　said　to　me：　鈥渢hat　was　a　very　nice　chap　named　normanwho鈥檚　spent　forty…two　years　studying　one　species　of　plant；　st。　john鈥檚　wort。　he　retired　in　1989；but　he　still　es　in　every　week。鈥�

鈥渉ow　do　you　spend　forty…two　years　on　one　species　of　plant？鈥潯�i　asked。

鈥渋t鈥檚　remarkable；　isn鈥檛　it？鈥潯�fortey　agreed。　he　thought　for　a　moment。　鈥渉e鈥檚　very　thoroughapparently。鈥潯�the　lift　door　opened　to　reveal　a　bricked…over　opening。　fortey　lookedconfounded。　鈥渢hat鈥檚　very　strange；鈥潯�he　said。　鈥渢hat　used　to　be　botany　back　there。鈥潯�he　puncheda　button　for　another　flo