the.lost.world-第39部分

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　　　　He　was　standing　in　the　high　hide　with　Thorne；　Eddie；　Malcolm；　and　the　kids；　looking　down　on　the　valley　floor　below。　Everyone　was　sweating　inside　the　little　observation　hut；　the　midday　air　was　still　and　hot。　Around　them；　the　grassy　meadow　was　deserted；　most　of　the　dinosaurs　had　moved　beneath　the　trees；　into　the　cool　of　the　shade。
　　　　The　exception　was　the　herd　of　apatosaurs；　which　had　left　the　trees　to　return　to　the　river；　where　they　were　now　drinking　once　again。　The　huge　animals　clustered　fairly　tightly　around　the　water's　edge。　In　the　same　vicinity；　but　more　spread　out；　were　the　high…crested　parasaurolophasaurs；　these　somewhat　smaller　dinosaurs　positioned　themselves　near　the　apatosaur　herd。
　　　　Thorne　wiped　sweat　out　of　his　eyes　and　said；　〃Why；　exactly；　are　you　pleased？〃
　　　　〃Because　of　what　we're　seeing　here；〃　Malcolm　said。　He　glanced　at　his　watch；　and　wrote　an　entry　in　his　notebook。　〃We're　getting　the　data　that　I　hoped　for。　It's　very　exciting。〃
　　　　Thorne　yawned；　sleepy　in　the　heat。　〃'Why　is　it　exciting？　The　dinosaurs　are　drinking。　What's　the　big　deal？〃
　　　　〃Drinking　again；〃　Levine　corrected　him。　〃For　the　second　time　in　an　hour。　At　midday。　Such　fluid　intake　is　highly　suggestive　of　the　thermoregulatory　strategies　these　large　creatures　employ。〃
　　　　〃You　mean　they　drink　a　lot　to　stay　cool；〃　Thorne　said；　always　impatient　with　jargon。
　　　　〃Yes。　Clearly　they　do。　Drink　a　lot。　But　in　my　view；　their　return　to　the　river　may　have　another　significance　entirely。〃
　　　　〃Which　is？〃
　　　　〃e；　e；〃　Levine　said；　pointing。　〃Look　at　the　herds。　Look　how　they　are　arranged　spatially。　We　are　seeing　something　that　no　one　has　witnessed　before；　or　even　suspected；　for　dinosaurs。　We're　seeing　nothing　less　than　inter…species　symbiosis。〃
　　　　〃We　are？〃
　　　　Yes；〃　Levine　said。　〃The　apatosaurs　and　the　parasaurs　are　together。　I　saw　them　together　yesterday；　too。　I'll　bet　that　they're　always　together；　when　they're　out　on　the　open　plain。　Undoubtedly　you　are　wondering　why。〃
　　　　〃Undoubtedly；〃　Thorne　said。
　　　　〃The　reason；〃　Levine　said；　〃is　that　the　apatosaurs　are　very　strong　but　weak…sighted；　whereas　the　parasaurs　are　smaller；　but　have　very　sharp　vision。　So　the　two　species　stay　together　because　they　provide　a　mutual　defense。　just　the　way　zebras　and　baboons　stay　together　on　the　African　plain。　Zebras　have　a　good　sense　of　smell；　and　baboons　have　good　eyesight。　Together　they're　more　effective　against　predators　than　either　is　alone。〃
　　　　〃And　you　think　this　is　true　of　the　dinosaurs　because。。。〃
　　　　〃It's　rather　obvious；〃　Levine　said。　〃Just　look　at　the　behavior。　When　the　two　herds　were　alone；　each　clustered　tightly　among　themselves。　But　when　they're　together；　the　parasaurs　spread　out；　abandoning　their　former　herd　arrangement；　to　form　an　outer　ring　around　the　apatosaurs。　Just　as　you　see　them　now。　That　can　only　mean　that　individual　paras　are　going　to　be　protected　by　the　apatosaur　herd。　And　vice　versa。　It　can　only　be　a　mutual　predator　defense。〃
　　　　As　they　watched；　one　of　the　parasaurs　lifted　its　head；　and　stared　across　the　river。　It　honked　mournfully；　a　long　musical　sound。　All　the　other　parasaurs　looked　up　and　stared；　too。　The　apatosaurs　continued　to　drink　at　the　river；　although　one　or　two　adults　raised　their　long　necks。
　　　　In　the　midday　heat；　insects　buzzed　around　them；　Thorne　said；　〃So　where　are　the　predators？〃
　　　　〃Right　there；〃　Malcolm　said；　pointing　toward　a　stand　of　trees　on　the　other　side　of　the　river；　not　far　from　the　water。
　　　　Thorne　looked；　and　saw　nothing。
　　　　〃Don't　you　see　them？〃
　　　　〃No。〃
　　　　〃Keep　looking。　They're　small；　lizard…like　animals。　Dark　brown。　Raptors；〃　he　said。
　　　　Thorne　shrugged。　He　still　saw　nothing。　Standing　beside　him；　Levine　began　to　eat　a　power　bar。　Preoccupied　with　holding　the　binoculars；　he　dropped　the　wrapper　on　the　floor　of　the　hide。　Bits　of　paper　fluttered　to　the　ground　below。
　　　　〃How　are　those　things？〃　Arby　said。
　　　　〃Okay。　A　little　sugary。〃
　　　　〃Got　any　more？〃　he　said。　
　　　　Levine　rummaged　in　his　pockets　and　gave　him　one。　Arby　broke　it　in　half；　and　gave　half　to　Kelly。　He　began　to　unwrap　his　half；　carefully　folding　the　paper；　putting　it　neatly　in　his　pocket。
　　　　〃You　realize　this　is　all　highly　significant；〃　Malcolm　said。　〃For　the　question　of　extinction。　Already　it's　obvious　that　the　extinction　of　the　dinosaurs　is　a　far　more　plex　problem　than　anyone　has　recognized。〃
　　　　〃It　is？〃　Arby　said。
　　　　〃Well；　consider；〃　Malcolm　said。　〃All　extinction　theories　are　based　on　the　fossil　record。　But　the　fossil　record　doesn't　show　the　sort　of　behavior　we're　seeing　here。　It　doesn't　record　the　plexity　of　groups　interacting。〃
　　　　〃Because　fossils　are　just　bones；〃　Arby　said。
　　　　〃Right。　And　bones　are　not　behavior。　When　you　think　about　it；　the　fossil　record　is　like　a　series　of　photographs：　frozen　moments　from　what　is　really　a　moving；　ongoing　reality。　Looking　at　the　fossil　record　is　like　thumbing　through　a　family　photo　album。　You　know　that　the　album　isn't　plete。　You　know　life　happens　between　the　pictures。　But　you　don't　have　any　record　of　what　happens　in　between；　you　only　have　the　pictures。　So　you　study　them；　and　study　them。　And　pretty　soon；　you　begin　to　think　of　the　album　not　as　a　series　of　moments；　but　as　reality　itself。　And　you　begin　to　explain　everything　in　terms　of　the　album；　and　you　forget　the　underlying　reality。
　　　　〃And　the　tendency；〃　Malcolm　said；　〃has　been　to　think　in　terms　of　physical　events。　To　assume　that　some　external　physical　event　caused　the　extinctions。　A　meteor　hits　the　earth；　and　changes　the　weather。　Or　volcanoes　erupt；　and　change　the　weather。　Or　a　meteor　causes　the　volcanoes　to　erupt　and　change　the　weather。　Or　vegetation　changes；　and　species　starve　and　bee　extinct。　Or　a　new　disease　arises；　and　species　bee　extinct。　Or　a　new　plant　arises；　and　poisons　all　the　dinosaurs。　In　every　case；　what　is　imagined　is　some　external　event。　But　what　nobody　imagines　is　that　the　animals　themselves　might　have　changed…not　in　their　bones；　but　their　behavior。　Yet　when　you　look　at　animals　like　these；　and　see　how　intricately　their　behavior　is　interrelated；　you　realize　that　a　change　in　group　behavior　could　easily　lead　to　extinction。〃
　　　　〃But　why　would　group　behavior　change？〃　Thorne　said。　〃If　there　wasn't　some　external　catastrophe　to　force　it；　why　should　the　behaviour　change？〃
　　　　〃Actually；〃　Malcolm　said；　〃behavior　is　always　changing；　all　the　time。　Our　planet　is　a　dynamic；　active　environment。　Weather　is　changing。　The　land　is　changing。　Continents　drift。　Oceans　rise　and　fall。　Mountains　thrust　up　and　erode　away。　All　the　organisms　on　the　planet　are　constantly　adapting　to　those　changes。　The　best　organisms　are　the　ones　that　can　adapt　most　rapidly。　That's　why　it's　hard　to　see　how　a　catastrophe　that　produces　a　large　change　could　cause　extinction；　since　so　much　change　is　occurring　all　the　time；　anyway。〃
　　　　〃In　that　case；〃　Thorne　said；　〃what　causes　extinction？〃
　　　　〃Certainly　not　rapid　change　alone；〃　Malcolm　said。　〃The　facts　tell　us　that　clearly。〃
　　　　〃What　facts？〃
　　　　〃After　every　major　environmental　change；　a　wave　of　extinctions　as　usually　followed…but　not　right　away。　Extinctions　only　occur　thousands；　or　millions　of　years　later。　Take　the　last　glaciation　in　North　America。　The　glaciers　descended；　the　climate　changed　severely；　but　animals　didn't　die。　Only　after　the　glaciers　receded；　when　you'd　think　things　would　go　back　to　normal；　did　lots　of　species　bee　extinct。　That's　when　giraffes　and　tigers　and　mammoths　vanished　on　this　continent。　And　that's　the　usual　pattern。　It's　almost　as　if　species　are　weakened　by　the　major　change；　but　die　off　later。　It's　a　well…recognized　phenomenon。〃
　　　　〃It's　called　Softening　Up　the　Beachhead；〃　Levine　said。　〃And　what's　the　explanation　for　it？〃
　　　　Levine　was　silent。
　　　　〃There　is　none〃　Malcolm　said。　〃It's　a　paleontological　mystery。　But　I　believe　that　plexity　theory　has　a　lot　to　tell　us　about　it。　Because　if　the　notion　of　life　at　the　edge　of　chaos　is　true；　then　major　change　pushes　animals　closer　to　the　edge。　It　destabilizes　all　sorts　of　behavior。　And　when　the　environment　goes　back　to　normal；　it's　not　really　a　return　to　normal。　In　evolutionary　terms；　it's　another　big　change；　and　it's　just　too　much　to　keep　up　with。　I　believe　that　new　behavior　in　populations　can　emerge　in　unexpected　ways；　and　I　think　I　know　why　the　dinosaurs　…　〃
　　　　〃What's　that？〃　Thorne　said。
　　　　Thorne　was　looking　at　the　trees；　and　saw　a　single　dinosaur　hop　out　into　view。　It　was　rather　slender；　agile　on　its　hind　legs；　balancing　with　a　stiff　tail。　It　was　six　feet　tall；　green…brown　with　dark…red　stripes；　like　a　tiger。
　　　　〃That；〃　Malcolm　said；　〃is　a　velociraptor。〃
　　　　Thorne　turned　to　Levine。　〃That's　what　chased　you　up　in　the　tree？　It　looks　ugly。〃
　　　　〃Efficient；〃　Levine　said。　〃Those　animals　are　brilliantly　constructed　killing　machines。　Arguably　the　most　efficient　predators　in　the　history　of　the　planet。　The　one　that　just　stepped　out　will　be　the　alpha　animal。　It　leads　the　pack。〃
　　　　Thorne　saw　other　movement　beneath　the　trees。　〃There's　more。〃
　　　　〃Oh　yes；〃　Levine　said。　〃This　particular　pack　is　very　large。〃　He　picked　up　binoculars；　and　peered　through　them。　〃I'd　like　to　locate　their　nest；　he　said。　〃I　haven't　been　able　to　find　it　anywhere　on　the　island。　Of　course　they're　secretive；　but　even　so。。。〃
　　　　The　parasaurs　were　all　crying　loudly；　moving　clo