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时间:2018-10-06
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1、ThePopulationSurprise(出人意料的人口变化)Text1ThePopulationSurprisebyMaxSingerWilltheworld'spopulationkeepincreasingascommonlybelieved?Whatarethefactorsthataccountforitschange?Pleasereadthefollowingarticleandmakeoutitsviewpoints.Fiftyyearsfromnowtheworld'spopulationwillbede
2、clining,withnoendinsight.Unlesspeople'svalueschangegreatly,severalcenturiesfromnowtherecouldbefewerpeoplelivingintheentireworldthanintheUnitedStatestoday.Thebigsurpriseofthepasttwentyyearsisthatinnotonecountrydidfertilitystopfallingwhenitreachedthereplacementrate-2
3、.1childrenperwoman.InItaly,forexample,theratehasfallento1.2.InWesternEuropeasawholeandinJapanitisdownto1.5.Theevidencenowindicatesthatwithinfiftyyearsorsoworldpopulationwillpeakatabouteightbillionbeforestartingafairlyrapiddecline.Becauseinthepasttwocenturiesworldpo
4、pulationhasincreasedfromonebilliontonearlysixbillion,manypeoplestillfearthatitwillkeep“exploding”untiltherearetoomanypeoplefortheearthtosupport.Butthatislikefearingthatyourbabywillgrowto1000poundsbecauseitsweightdoublesthreetimesinitsfirstsevenyears.Worldpopulation
5、wasgrowingbytwopercentayearinthe1960s;therateisnowdowntoonepercentayear,andifthepatternsofthepastcenturydon'tchangeradically,itwillheadintonegativenumbers.Thisviewiscomingtobewidelyacceptedamongpopulationexperts,evenasthepubliccontinuestofocusonthethreatofuncontrol
6、ledpopulationgrowth.AslongagoasSeptemberof1974ScientificAmericanpublishedaspecialissueonpopulationthatdescribedwhatdemographers1hadbeguncallingthe“demographictransition”fromtraditionalhighratesofbirthanddeathtothelowonesofmodernsociety.Theexpertsbelievedthatbirthan
7、ddeathrateswouldbemoreorlessequalinthefuture,astheyhadbeeninthepast,keepingtotalpopulationstableafteralevelof10-12billionpeoplewasreachedduringthetransition.Developmentsoverthepasttwentyyearsshowthattheexpertswererightinthinkingthatpopulationwon'tkeepgoingupforever
8、.Theywerewronginthinkingthatafteritstopsgoingup,itwillstaylevel.Theexperts'assumptionthatpopulationwouldstabilizebecausebirthrateswouldstopfallin
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