the.lost.world-第42部分

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　　　　He　shrugged。　The　troubling　idea　hung　in　the　back　of　his　mind；　but　he　couldn't　get　to　it。　He　'ust　couldn't　get　it。

Reluctantly；　Levine　turned　his　attention　to　the　parasaur　herd；　browsing　by　the　river；　alongside　the　apatosaurs。　He　listened　as　the　parasaurs　made　their　distinctive；　low　trumpeting　sounds。　Levine　noticed　that　most　often　the　parasaurs　made　a　sound　of　short　duration；　a　kind　of　rumbling　honk。　Sometimes；　several　animals　made　this　sound　at　once；　or　very　nearly　overlapping；　so　it　seemed　to　be　an　audible　way　of　indicating　to　the　herd　where　all　the　members　were。　Then　there　was　a　much　longer；　more　dramatic　trumpeting　call。　This　sound　was　made　infrequently；　and　only　by　the　two　largest　animals　in　the　herd；　which　raised　their　heads　and　trumpeted　loud　and　long。　But　what　did　the　sound　mean？
　　　　Standing　there　in　the　hot　sun；　Levine　decided　to　perform　a　little　experiment。　He　cupped　his　hands　around　his　mouth；　and　imitated　the　parasaur's　trumpeting　cry。　It　wasn't　a　very　good　imitation；　but　immediately　the　lead　parasaur　looked　up；　turning　its　head　this　way　and　that。　And　it　gave　a　low　cry；　answering　Levine。
　　　　Levine　gave　a　second　call。
　　　　Again；　the　parasaur　answered。　　　　
　　　　Levine　was　pleased　by　this　response；　and　made　an　entry　in　his　notebook。　But　when　he　looked　up　again；　he　was　surprised　to　see　that　the　parasaur　herd　was　drifting　away　from　the　apatosaurs。　They　collected　together；　formed　a　single　line；　and　began　to　walk　directly　toward　the　high　hide。
　　　　Levine　started　to　sweat。
　　　　What　had　he　done？　In　some　bizarre　corner　of　his　mind；　he　wondered　if　he　had　imitated　a　mating　cry。　That　was　all　he　needed；　to　attract　a　randy　dinosaur。　Who　knew　how　these　animals　behaved　in　mating？　With　growing　anxiety；　he　watched　them　march　forward。　Probably；　he　should　call　Malcolm；　and　ask　his　advice。　But　as　he　thought　about　it；　he　realized　that　by　imitating　that　cry　he　had　interfered　with　the　environment；　introduced　a　new　variable。　He　had　done　exactly　what　he　had　told　Thorne　he　did　not　intend　to　do。　It　was　thoughtless；　of　course。　And　surely　not　very　important　in　the　scheme　of　things。　But　Malcolm　was　certain　to　give　him　hell　about　it。
　　　　Levine　lowered　his　binoculars　and　stared。　A　deep　trumpeting　sound　reverberated　through　the　air；　so　loud　it　hurt　his　ears。　The　ground　began　to　shake；　making　the　high　hide　sway　back　and　forth　precariously。
　　　　My　God；　he　thought。　They're　ing　right　for　me。　He　bent　over；　and　with　fumbling　fingers；　searched　his　backpack　for　the　radio。

Problems　of　Evolution

In　the　trailer；　Thorne　took　the　rehydrated　meals　out　of　the　microwave；　and　passed　the　plates　around　the　little　table。　Everyone　unwrapped　them；　and　began　to　cat。　Malcolm　poked　his　fork　into　the　food。　〃What　is　this　stuff？〃
　　　　〃Herb…baked　chicken　breast；〃　Thorne　said。
　　　　Malcolm　took　a　bite；　and　shook　his　head。　〃Isn't　technology　wonderful？〃　he　said。　〃They　manage　to　make　it　taste　just　like　cardboard。〃
　　　　Malcolm　looked　at　the　two　kids　seated　opposite　him；　who　were　eating　energetically。　Kelly　glanced　up　at　him；　and　gestured　with　her　fork　at　the　books　strapped　into　a　shelf　beside　the　table。　〃One　thing　I　don't　understand。〃
　　　　〃Only　one？〃　Malcolm　said。
　　　　〃All　this　business　about　evolution；〃　she　said。　〃Darwin　wrote　his　book　a　long　time　ago；　right？〃
　　　　〃Darwin　published　the　Origin　of　Species　in　1859；〃　Malcolm　said。
　　　　〃And　by　now；　everybody　believes　it；　isn't　that　right？〃
　　　　〃I　think　it's　fair　to　say　that　every　scientist　in　the　world　agrees　that　evolution　is　a　feature　of　life　on　earth；〃　Malcolm　said。　〃And　that　we　are　descended　from　animal　ancestors。　Yes。〃
　　　　〃Okay；〃　Kelly　said。　〃So；　what's　the　big　deal　now？〃
　　　　Malcolm　smiled。　〃The　big　deal；〃　he　said；　〃is　that　everybody　agrees　evolution　occurs；　but　nobody　understands　how　it　works。　There　are　big　problems　with　the　theory。　And　more　and　more　scientists　are　admitting　it。〃

Malcolm　pushed　his　plate　away。　〃You　have　to　track　the　theory；〃　he　said；　〃over　a　couple　of　hundred　years。　Start　with　Baron　Georges　Cuvier：　the　most　famous　anatomist　in　the　world　in　his　day；　living　in　the　intellectual　center　of　the　world；　Paris。　Around　1800；　people　began　digging　up　old　bones；　and　Cuvier　realized　that　they　belonged　to　animals　no　longer　found　on　earth。　That　was　a　problem；　because　back　in　1800；　everybody　believed　that　all　the　animal　species　ever　created　were　still　alive。　The　idea　seemed　reasonable　because　the　earth　was　thought　to　be　only　a　few　thousand　years　old。　And　because　God；　who　had　created　all　the　animals；　would　never　let　any　of　his　creations　bee　extinct。　So　extinction　was　agreed　to　be　impossible。　Cuvier　agonized　over　these　dug…up　bones；　but　he　finally　concluded　that　God　or　no　God；　many　animals　had　bee　extinct　…　as　a　result；　he　thought；　of　worldwide　catastrophes；　like　Noah's　flood。〃
　　　　〃Okay。。。〃
　　　　〃So　Cuvier　reluctantly　came　to　believe　in　extinction；〃　Malcolm　said；　〃but　he　never　accepted　evolution。　In　Cuvier's　mind；　evolution　didn't　occur。　Some　animals　died　and　some　survived；　but　none　evolved。　In　his　view；　animals　didn't　change。　Then　along　came　Darwin；　who　said　that　animals　did　evolve；　and　that　the　dug…up　bones　were　actually　the　extinct　predecessors　of　living　animals。　The　implications　of　Darwin's　idea　upset　lots　of　people。　They　didn't　like　to　think　of　God's　creations　changing；　and　they　didn't　like　to　think　of　monkeys　in　their　family　trees。　It　was　embarrassing　and　offensive。　The　debate　was　fierce。　But　Darwin　amassed　a　tremendous　amount　of　factual　data　…　he　had　made　an　overwhelming　case。　So　gradually　his　idea　of　evolution　was　accepted　by　scientists；　and　by　the　world　at　large。　But　the　question　remained：　how　does　evolution　happen？　For　that；　Darwin　didn't　have　a　good　answer。〃
　　　　〃　Natural　selection；〃　Arby　said。
　　　　〃Yes；　that　was　Darwin's　explanation。　The　environment　exerts　pressure　which　favors　certain　animals；　and　they　breed　more　often　in　subsequent　generations；　and　that's　how　evolution　occurs。　But　as　many　people　realized；　natural　selection　isn't　really　an　explanation。　It's　just　a　definition：　if　an　animal　succeeds；　it　must　have　been　selected　for。　But　what　in　the　animal　is　favored？　And　how　does　natural　selection　actually　operate？　Darwin　had　no　idea。　And　neither　did　anybody　else　for　another　fifty　years。〃
　　　　〃But　it's　genes；〃　Kelly　said。
　　　　〃Okay；〃　Malcolm　said。　〃Fine。　We　e　to　the　twentieth　century。　Mendel's　work　with　plants　is　rediscovered。　Fischer　and　Wright　do　population　studies。　Pretty　soon　we　know　genes　control　heredity…whatever　genes　are。　Remember；　through　the　first　half　of　the　century；　all　during　World　War　I　and　World　War　II；　nobody　had　any　idea　what　a　gene　was。　After　Watson　and　Crick　in　1953；　we　knew　that　genes　were　nucleotides　arranged　in　a　double　helix。　Great。　And　we　knew　about　mutation。　So　by　the　late　twentieth　century；　we　have　a　theory　of　natural　selection　which　says　that　mutations　arise　spontaneously　in　genes；　that　the　environment　favors　the　mutations　that　are　beneficial；　and　out　of　this　selection　process　evolution　occurs。　It's　simple　and　straightforward。　God　is　not　at　work。　No　higher　organizing　principle　involved。　In　the　end；　evolution　is　just　the　result　of　a　bunch　of　mutations　that　either　Survive　or　die。　Right？〃
　　　　〃Right；〃　Arby　said。
　　　　〃But　there　are　problems　with　that　idea；〃　Malcolm　said。　〃First　of　all；　there's　a　time　problem。　A　single　bacterium　…　the　earliest　form　of　life　has　two　thousand　enzymes。　Scientists　have　estimated　how　long　it　would　take　to　randomly　assemble　those　enzymes　from　a　primordial　soup。　Estimates　run　from　forty　billion　years　to　one　hundred　billion　years。　But　the　earth　is　only　four　billion　years　old。　So；　chance　alone　seems　too　slow。　Particularly　since　we　know　bacteria　actually　appeared　only　four　hundred　million　years　after　the　earth　began。　Life　appeared　very　fast　…　which　is　why　some　scientists　have　decided　life　on　earth　must　be　of　extraterrestrial　origin。　Although　I　think　that's　just　evading　the　issue。〃
　　　　〃Okay。。。〃
　　　　〃Second；　there's　the　coordination　problem。　If　you　believe　the　current　theory；　then　all　the　wonderful　plexity　of　life　is　nothing　but　the　accumulation　of　chance　events　…　a　bunch　of　genetic　accidents　strung　together。　Yet　when　we　look　closely　at　animals；　it　appears　as　if　many　elements　must　have　evolved　simultaneously。　Take　bats；　which　have　echolocation…they　navigate　by　sound。　To　do　that；　many　things　must　evolve。　Bats　need　a　specialized　apparatus　to　make　sounds；　they　need　specialized　ears　to　hear　echoes；　they　need　specialized　brains　to　interpret　the　sounds；　and　they　need　specialized　bodies　to　dive　and　swoop　and　catch　insects。　If　all　these　things　don't　evolve　simultaneously；　there's　no　advantage。　And　to　imagine　all　these　things　happen　purely　by　chance　is　like　imagining　that　a　tornado　can　hit　a　junkyard　and　assemble　the　Parts　into　a　working　747　airplane。　It's　very　hard　to　believe。〃
　　　　〃Okay；〃　Thorne　said。　〃I　agree。〃
　　　　〃Next　problem。　Evolution　doesn't　always　act　like　a　blind　force　should。　Certain　environmental　niches　don't　get　filled。　Certain　plants　don't　get　eaten。　And　certain　animals　don't　evolve　much。　Sharks　haven't　changed　for　a　hundred　and　sixty　million　years。　Opossums　haven't　changed　since　dinosaurs　became　extinct；　sixty…five　million　years　ago。　The　environments　for　these　animals　have　changed　dramatically；　but　the　animals　have　remained　almost　the　s