the.lost.world-第43节

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imals　have　changed　dramatically；　but　the　animals　have　remained　almost　the　same。　Not　exactly　the　same；　but　almost。　In　other　words；　it　appears　they　haven't　responded　to　their　environment。〃
　　　　〃Maybe　they're　still　well　adapted；〃　Arby　said。
　　　　〃Maybe。　Or　maybe　there's　something　else　going　on　that　we　don't　understand。〃
　　　　〃　Like　what？〃
　　　　〃Like　other　rules　that　influence　the　oute。〃
　　　　Thorne　said；　〃Are　you　saying　evolution　is　directed？〃
　　　　〃No；〃　Malcolm　said。　〃That's　Creationism　and　it's　wrong。　Just　plain　wrong。　But　I　am　saying　that　natural　selection　acting　on　genes　is　probably　not　the　whole　story。　It's　too　simple。　Other　forces　are　also　at　work。　The　hemoglobin　molecule　is　a　protein　that　is　folded　like　a　sandwich　around　a　central　iron　atom　that　binds　oxygen。　Hemoglobin　expands　and　contracts　when　it　takes　on　and　gives　up　oxygen…like　a　tiny　molecular　lung。　Now；　we　know　the　sequence　of　amino　acids　that　make　up　hemoglobin。　But　we　don't　know　how　to　fold　it。　Fortunately；　we　don't　need　to　know　that；　because　if　you　make　the　molecule；　it　folds　all　by　itself。　It　organizes　itself。　And　it　turns　out；　again　and　again；　that　living　things　seem　to　have　a　self…organizing　quality。　Proteins　fold。　Enzymes　interact。　Cells　arrange　themselves　to　form　organs　and　the　organs　arrange　themselves　to　form　a　coherent　individual。　Individuals　organize　themselves　to　make　a　population。　And　populations　organize　themselves　to　make　a　coherent　biosphere。　From　plexity　theory；　we're　starting　to　have　a　sense　of　how　this　self…organization　may　happen；　and　what　it　means。　And　it　implies　a　major　change　in　how　we　view　evolution。〃
　　　　〃But；〃　Arby　said；　〃in　the　end；　evolution　still　must　be　the　result　of　the　environment　acting　on　genes。〃
　　　　〃I　don't　think　it's　enough；　Arb；〃　Malcolm　said。　〃I　think　more　is　involved　…　I　think　there　has　to　be　more；　even　to　explain　how　our　own　species　arose。〃

〃About　three　million　years　ago；〃　Malcolm　said；　〃some　African　apes　that　had　been　living　in　trees　came　down　to　the　ground。　There　was　nothing　special　about　these　apes。　Their　brains　were　small　and　they　weren't　especially　smart。　They　didn't　have　claws　or　sharp　teeth　for　weapons。　They　weren't　particularly　strong；　or　fast。　They　were　certainly　no　match　for　a　leopard。　But　because　they　were　short；　they　started　standing　upright　on　their　hind　legs；　to　see　over　the　tall　African　grass。　That's　how　it　began。　just　some　ordinary　apes；　looking　out　over　the　grass。
　　　　〃As　time　went　on；　the　apes　stood　upright　more　and　more　of　the　time。　That　left　their　hands　free　to　do　things。　Like　all　apes；　they　were　tool…users。　Chimps；　for　example；　use　twigs　to　fish　for　termites。　That　sort　of　thing。　As　time　went　on；　our　ape　ancestors　developed　more　plex　tools。　That　stimulated　their　brains　to　grow　in　size　and　plexity。　It　began　a　spiral：　more　plex　tools　provoked　more　plex　brains　which　provoked　more　plex　tools。　And　our　brains　literally　exploded；　in　evolutionary　terms。　Our　brains　more　than　doubled　in　size　in　about　a　million　years。　And　that　caused　problems　for　us。〃
　　　　〃Like　what？〃
　　　　〃Like　getting　born；　for　one　thing。　Big　brains　can't　pass　through　the　birth　canal　…　which　means　that　both　mother　and　child　die　in　childbirth。　That's　no　good。　What's　the　evolutionary　response？　To　make　human　infants　born　very　early　in　development；　when　their　brains　are　still　small　enough　to　pass　through　the　pelvis。　It's　the　marsupial　solution　…　most　of　the　growth　occurs　outside　the　mother's　body。　A　human　child's　brain　doubles　during　the　first　year　of　life。　That's　a　good　solution　to　the　problem　of　birth；　but　it　creates　other　problems。　It　means　that　human　children　will　be　helpless　long　after　birth。　The　infants　of　many　mammals　can　walk　minutes　after　they're　born。　Others　walk　in　a　few　days；　or　weeks。　But　human　infants　can't　walk　for　a　full　year。　They　can't　feed　themselves　for　even　longer。　So　one　price　of　big　brains　was　that　our　ancestors　had　to　evolve　new；　stable　social　organizations　to　permit　long…term　child　care；　lasting　many　years；　These　big…brained；　totally　helpless　children　changed　society。　But　that's　not　the　most　important　consequence。〃
　　　　〃No？〃
　　　　〃No。　Being　born　in　an　immature　state　means　that　human　infants　have　unformed　brains。　They　don't　arrive　with　a　lot　of　built…in；　instinctive　behavior。　Instinctively；　a　newborn　infant　can　suck　and　grasp；　but　that's　about　all。　plex　human　behavior　is　not　instinctive　at　all。　So　human　societies　had　to　develop　education　to　train　the　brains　of　their　children。　To　teach　them　how　to　act。　Every　human　society　expends　tremendous　time　and　energy　teaching　its　children　the　right　way　to　behave。　You　look　at　a　simpler　society；　in　the　rain　forest　somewhere；　and　you　find　that　every　child　is　born　into　a　network　of　adults　responsible　for　helping　to　raise　the　child。　Not　only　parents；　but　aunts　and　uncles　and　grandparents　and　tribal　elders。　Some　teach　the　child　to　hunt　or　gather　food　or　weave；　some　teach　them　about　sex　or　war。　But　the　responsibilities　are　clearly　defined；　and　if　a　child　does　not　have；　say；　a　mother's　brother's　sister　to　do　a　specific　teaching　job；　the　people　get　together　and　appoint　a　substitute。　Because　raising　children　is；　in　a　sense；　the　reason　the　society　exists　in　the　first　place。　It's　the　most　important　thing　that　happens；　and　it's　the　culmination　of　all　the　tools　and　language　and　social　structure　that　has　evolved。　And　eventually；　a　few　million　years　later；　we　have　kids　using　puters。
　　　　〃Now；　if　this　picture　makes　sense；　where　does　natural　selection　act？　Does　it　act　on　the　body；　enlarging　the　brain？　Does　it　act　on　the　developmental　sequence；　pushing　the　kids　out　early？　Does　it　act　on　social　behavior；　provoking　cooperation　and　child…caring？　Or　does　it　act　everywhere　all　at　once　…　on　bodies；　on　development；　and　on　social　behavior？〃
　　　　〃Everywhere　at　once；〃　Arby　said。
　　　　〃I　think　so；〃　Malcolm　said。　〃But　there　may　also　be　parts　of　this　story　that　happen　automatically；　the　result　of　self…organization。　For　example；　infants　of　all　species　have　a　characteristic　appearance。　Big　eyes；　big　heads；　small　faces；　uncoordinated　movements。　That's　true　of　kids　and　puppies　and　baby　birds。　And　it　seems　to　provoke　adults　of　all　species　to　act　tenderly　toward　them。　In　a　sense；　you　might　say　infant　appearance　seems　to　self…organize　adult　behavior。　And　in　our　case；　a　good　thing；　too。〃
　　　　Thorne　said；　〃What　does　that　have　to　do　with　dinosaur　extinction？〃
　　　　〃Self…organizing　principles　can　act　for　better　or　worse。　Just　as　self…organization　can　coordinate　change；　it　can　also　lead　a　population　into　decline；　and　cause　it　to　lose　its　edge。　On　this　island；　my　hope　is　we'll　see　self…organizing　adaptations　in　the　behavior　of　real　dinosaurs　…　and　it'll　tell　us　why　they　became　extinct。　In　fact；　I'm　pretty　sure　we　already　know　why　the　dinosaurs　became　extinct。〃
　　　　The　radio　clicked。　〃Bravo；〃　Levine　said；　over　the　inter。　〃I　couldn't　have　put　it　better　myself。　But　perhaps　you　better　see　what　is　happening　out　here。　The　parasaurs　are　doing　something　very　interesting；　Ian。〃
　　　　〃What's　that？〃
　　　　〃e　and　look。〃
　　　　〃Kids；〃　Malcolm　said；　〃you　stay　here　and　watch　the　monitors。〃　He　pressed　the　radio　button。　〃Richard？　We're　on　our　way。〃

Parasaurs

Richard　Levine　gripped　the　railing　of　the　high　hide；　and　watched　tensely。　Directly　ahead；　ing　into　view　over　a　low　rise；　he　saw　the　magnificent　head　of　a　Parasaurolophus　walkeri。　The　duck…billed　hadrosaur's　skull　was　three　feet　long；　but　it　was　made　larger　by　a　long　horned　crest　that　extended　backward　high　in　the　air。
　　　　As　the　animal　approached；　Levine　could　see　the　green　mottling　on　the　head。　He　saw　the　long　powerful　neck；　the　heavy　body　with　its　light　green　underbelly。　The　parasaurolophus　was　twelve　feet　tall；　and　roughly　the　size　of　a　large　elephant。　Its　head　was　almost　as　high　as　the　floor　of　the　high　hide。　The　animal　moved　steadily　toward　him；　its　footsteps　thumping　on　the　ground。　Moments　later；　he　saw　a　second　head　appear　over　the　rise…then　a　third；　and　a　fourth。　The　animals　trumpeted；　and　walked　in　single　file　directly　toward　him。
　　　　Within　moments；　the　lead　animal　was　abreast　of　the　hide。　Levine　held　his　breath　as　it　passed。　The　animal　stared　at　him；　its　large　brown　eye　rolling　to　watch　him。　It　licked　its　lips　with　a　dark…purple　tongue。　The　hide　shook　with　its　footsteps。　And　then　it　had　passed；　continuing　on　toward　the　jungle　behind。　Soon　after；　the　second　animal　passed。
　　　　The　third　animal　brushed　against　the　structure；　rocking　it　slightly。　But　the　dinosaur　did　not　seem　to　notice；　it　continued　steadily　on。　So　did　the　others。　One　by　one；　they　disappeared；　into　the　dense　foliage　behind　the　high　hide。　The　earth　ceased　to　vibrate。　It　was　then　that　he　saw　the　game　trail；　running　past　the　high　hide　and　into　the　jungle。
　　　　Levine　sighed。
　　　　His　body　relaxed　slowly。　He　picked　up　his　binoculars　and　took　a　deep　breath；　calming　himself　His　panic　faded。　He　began　to　feel　better。
　　　　And　then　he　thought：　What　are　they　doing？　Where　are　they　going？　Because；　as　he　considered　it；　the　behavior　of　the　parasaurs　seemed　extremely　strange。　They　had　been　in　a　defensive　cluster　while　they　fed；　but　in　movement　they　had　shifted　to　single　file　which　broke　the　usual　clumped　herd　pattern；　and　made　every　animal　vulnerable　to　predation。　Yet　the　behavior　was　clearly　organized。　Moving　in　single　file　must