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Don'twashthosefossils!
StandardmuseumpracticecanwashawayDNA.
1.Washing,brushingandvarnishingfossils—allstandardconservationtreatmentsusedbymanyfossilhuntersandmuseumcuratorsalike—vastlyreducesthechancesofrecoveringancientDNA.
2.Instead,excavatorsshouldbehandlingatleastsomeoftheirbountywithgloves,andfreezingsamplesastheyarefound,dirtandall,concludesapaperintheProceedingsoftheNationalAcademyofSciencestoday.
3.AlthoughmanypalaeontologistsknowanecdotallythatthisisthebestwaytouptheoddsofextractinggoodDNA,Eva-MariaGeigloftheJacquesMonodInstituteinParis,France,andhercolleagueshavenowshownjusthowimportantconservationpracticescanbe.Thisinformation,theysay,needstobehammeredhomeamongthepeoplewhoareactuallyoutinthefielddiggingupbones.
4.Geiglandhercolleagueslookedat3,200-year-oldfossilbonesbelongingtoasingleindividualofanextinctcattlespecies,calledanaurochs.ThefossilsweredugupatasiteinFranceattwodifferenttimes—eitherin1947,andstoredinamuseumcollection,orin2004,andconservedinsterileconditionsat-20oC.
5.Theteam'sattemptstoextractDNAfromthe1947bonesallfailed.Thenewlyexcavatedfossils,however,allyieldedDNA.
6.Becausetheboneshadbeenburiedforthesameamountoftime,andinthesameconditions,theconservationmethodhadtobetoblamesaysGeigl."AsmuchDNAwasdegradedinthese57yearsasinthe3,200yearsbefore,"shesays.
Washin,washout
7.Becausemanypalaeontologistsbasetheirworkontheshapeoffossilsalone,theirmethodsofconservationarenotdesignedtopreserveDNA,Geiglexplains.
8.Thebiggestproblemishowtheyarecleaned.Fossilsareoftenwashedtogetheron-siteinalargebath,whichcanallowwater—andcontaminantsintheformofcontemporaryDNA—topermeateintotheporousbones."NotonlyistheauthenticDNAgettingwashedout,butcontaminationisgettingwashedin,"saysGeigl.
9.MostancientDNAspecialistsknowthisalready,saysHendrikPoinar,anevolutionarygeneticistatMcMasterUniversityinOntario,Canada.Butthatdoesn'tmeanthatbestpracticehasbecomewidespreadamongthosewhoactuallyfindthefossils.
10.GettingholdoffossilsthathavebeenpreservedwiththeirDNAinmindreliesoncloserelationshipsbetweenlab-basedgeneticistsandtheexcavators,sayspalaeogeneticistSvantePbooftheMaxPlanckInstituteforEvolutionaryAnthropologyinLeipzig,Germany.Andthatonlyoccursinexceptionalcases,hesays.
11.Pbo'steam,whichhasbeensequencingNeanderthalDNA,continuallyfacestheseproblems."WhenyouwanttostudyancienthumanandNeanderthalremains,there'sabigissueofcontaminationwithcontemporaryhumanDNA,"hesays.
12.Thisdoesn'tmeanthatallmuseumspecimensarefatallyflawed,notesPbo.TheNeanderthalfossilsthatwererecentlysequencedinhisownlab,forexample,hadbeenpartofamuseumcollectiontreatedinthetraditionalway.ButPboiskeentoseesamplesoffossilsfromeverymajorfindpreservedinlinewithGeigl'srecommendations—justincase.
Warmandwet
13.Geiglherselfbelievesthat,withcooperationbetweenbenchandfieldresearchers,preservingfossilsproperlycouldopenupavenuesofdiscoverythathavelongbeenassumedclosed.
14.Muchhumanculturaldevelopmenttookplaceintemperateregions.DNAdoesnotsurvivewellinwarmenvironmentsinthefirstplace,andcanvanishwhenfossilsarewashedandtreated.Forthisreason,Geiglsays,mostancientDNAstudieshavebeendoneonpermafrostsamples,suchasthewoollymammoth,oronremainsshelteredfromtheelementsincoldcaves—includingcavebearandNeanderthalfossils.
15.Betterconservationmethods,andafocusonfreshfossils,couldboostDNAextractionfrommoredelicatespecimens,saysGeigl.Andthatcouldshedmorelightonthestoryofhumanevolution.
(640wordsnature)
Glossary
Palaeontologists古生物学家
Aurochs欧洲野牛
Neanderthal(人类学)尼安德特人，旧石器时代的古人类。
Permafrost(地理)永冻层
Questions1-6
AnswerthefollowingquestionsbyusingNOMORETHANTHREEWORDSforeachanswer.
1.Howdidpeopletraditionallytreatfossils?
2.WhatsuggestionsdoGeiglandhercolleaguesgiveonwhatshouldbedonewhenfossilsarefound?
3.Whatproblemsmaybeposediffossilbonesarewashedon-site?NameONE.
4.WhatcharacteristicdofossilboneshavetomakethemsusceptibletobecontaminatedwithcontemporaryDNAwhentheyarewashed?
5.Whatcouldbebetterunderstoodwhenconservationtreatmentsareimproved?
6.Thepassagementionedseveralanimalspeciesstudiedbyresearchers.Howmanyofthemarementioned?
Questions7-11
Dothefollowingstatementsagreewiththeinformationgiveninthepassage?PleasewriteTRUEifthestatementagreeswiththewriterFALSEifthestatementdoesnotagreewiththewriterNOTGIVENifthereisnoinformationaboutthisinthepassage.
7.IntheirpaperpublishedintheProceedingsoftheNationalAcademyofSciences，GeiglandhercolleagueshaveshownwhatconservationpracticesshouldbefollowedtopreserveancientDNA.
8.ThefossilbonesthatGeiglandhercolleaguesstudiedareallfromthesameaurochs.
9.Geneticistsdon'thavetoworkonsite.
10.OnlynewlyexcavatedfossilbonesusingnewconservationmethodssuggestedbyGeiglandhercolleaguescontainancientDNA.
11.Paaboisstillworriedaboutthepotentialproblemscausedbytreatmentsoffossilsintraditionalway.
Questions12-13
CompletethefollowingthestatementsbychoosingletterA-Dforeachanswer.
12.“Thisinformation”inparagraph3indicates:
[A]ItiscriticaltofollowproperpracticesinpreservingancientDNA.
[B]ThebestwayofgettinggoodDNAistohandlefossilswithgloves.
[C]Fossilhuntersshouldwearhome-madehammerswhilediggingupbones.
[D]Manypalaeontologistsknowhowoneshoulddointreatingfossils.
13.ThestudyconductedbyGeiglandhercolleaguessuggests:
[A]thefactthatancientDNAcannotberecoveredfromfossilbonesexcavatedinthepast.
[B]thecorrelationbetweentheamountofburyingtimeandthatoftherecoveredDNA.
[C]thepaceatwhichDNAdegrades.
[D]thecorrelationbetweenconservationpracticesanddegradationofDNA.
Passage2
Questions6to10arebasedonthefollowingpassage:
Thefoodweeatseemstohaveprofoundeffectsonourhealth.Althoughsciencehasmadeenormousstepsinmakingfoodmorefittoeat,ithas,atthesametime,mademanyfoodsunfittoeat.Someresearchhasshowntat40percentofcancerisrelatedtothedietaswell,especiallycancerofthecolon.Differentculturesatemorepronetogetcertainillnessesbecauseofthefoodthatischaracteristicinthesecultures.Thatfoodisrelatedtoillnessisnotanewdiscovery.In1945,governmentresearchersrealizedthatnitratesandnitrites,commonlyusedtopreservecolorinmeats,andotherfoodadditives,causedcancer.Yetthesecarcinogenicadditivesremaininourfood,anditbecomesmoredifficultallthetimetoknowwhichthingsonthepackaginglabelsofprocessedfoodarehelpfulorharmful.Theadditivesthatweeatarenotallsodirect.Farmersoftengivepenicillintobeefandpoultry,andbecauseofthis,penicillinhasbeenfoundinthemilkoftreatedcows.Sometimessimilardrugsareadministeredtoanimalsnotformedicinalpurposes,butforfinancialreasons.Thefarmersaresimplytryingtofattentheanimalsinordertoobtainahigherpriceonthemarket.AlthoughtheFoodandDrugAdministration(FDA)hastriedrepeatedlytocontroltheseprocedures,thepracticescontinue.
6.Howhassciencedoneadisservicetomankind?
A.Becauseofscience,mostofthefoodsweeattodayarecontaminated.
B.Ithascausedalackofinformationconcerningthevalueoffood.
C.Asaresultofscientificintervention,somepotentiallyharmfulsubstanceshasbeenaddedtoourfood.
D.Thescientistshavepreservedthecolorofmeats,butnotofvegetables.
7.Whatarenitratesusedfor?
A.Theypreservesflavorinpackagedfoods.
B.Theypreservethecolorofmeats.
C.Theyaretheobjectsofresearch.
D.Theycausetheanimalstobecomefatter.
8.TheFDAhastriedrepeatedlytocontrol.
A.theattempttofattentheanimals
B.theattempttocuresickanimals
C.theusingofdrugstoanimals
D.theusingofadditivestopreservethedoloroffood
9.Theword“carcinogenic”meansmostnearlythesameas.
A.trouble-makingB.color-retaining
C.money-savingD.cancer-causing
10.WhichofthefollowingstatementsisNOTtrue?
A.Drugsarealwaysgiventoanimalsformedicalreasons.
B.Someoftheadditivesinourfoodareaddedtothefooditselfandsomearegiventothelivinganimals.
C.Researchershaveknownaboutthepotentialhazardsofthefoodadditivesforoverthirty-fiveyears.
D.Foodmaycausefortypercentofcancerintheworld.
Inthelast12yearstotalemploymentintheUnitedStatesgrewfasterthanatanytimeinthepeacetimehistoryofanycountry–from82to110millionbetween1973and1985–thatis,byafullonethird.Theentiregrowth,however,wasinmanufacturing,andespeciallyinno–blue-collarjobs…
Thistrendisthesameinalldevelopedcountries,andis,indeed,evenmorepronouncedinJapan.Itisthereforehighlyprobablethatin25yearsdevelopedcountriessuchastheUnitedStatesandJapanwillemploynolargeraproportionofthelaborforceInmanufacturingthandevelopedcountriesnowemployinfarming–atmost,10percent.TodaytheUnitedStatesemploysaround18millionpeopleinblue-collarjobsinmanufacturingindustries.By2010,thenumberislikelytobenomorethan12million.Insomemajorindustriesthedropwillbeevensharper.Itisquiteunrealistic,forinstance,toexpectthattheAmericanautomobileindustrywillemploymorethanone–thirdofitspresentblue-collarforce25yearshence,eventhoughproductionmightbe50percenthigher.
Ifacompany,anindustryoracountrydoesnotinthenextquartercenturysharplyincreasemanufacturingproductionandatthesametimesharplyreducetheblue-collarworkforce,itcannothopetoremaincompetitive–oreventoremain“developed.”Theattempttopreservesuchblue–collarjobsisactuallyaprescriptionforunemployment…
ThisisnotaconclusionthatAmericanpoliticians,laborleadersorindeedthegeneralpubliccaneasilyunderstandoraccept.WhatconfusestheissueevenmoreitthattheUnitedStatesisexperiencingseveralseparateanddifferentshiftsinthemanufacturingeconomy.Oneistheaccelerationofthesubstitutionofknowledgeandcapitalformanuallabor.Wherewespokeofmechanizationafewdecadesago,wenowspeakof“robotization“or“automation.”Thisisactuallymoreachangeinterminologythanachangeinreality.WhenHenryFordintroducedtheassemblylinein1909,hecutthenumberofman–hoursrequiredtoproduceamotorcarbysome80percentintwoorthreeyears–farmorethananyoneexpectstoresultfromeventhemostcompleterobotization.Butthereisnodoubtthatwearefacinganew,sharpaccelerationinthereplacementofmanualworkersbymachines–thatis,bytheproductsofknowledge.
1.Accordingtotheauthor,theshrinkageinthemanufacturinglaborforcedemonstrates______.
A.thedegreetowhichacountry’sproductionisrobotized
B.areductioninacountry’smanufacturingindustries
C.aworseningrelationshipbetweenlaborandmanagement
D.thedifferencebetweenadevelopedcountryandadevelopingcountry
2.Accordingtotheauthor,incoming25years,adevelopedcountryorindustry,inordertremaincompetitive,oughtto______.
A.reducethepercentageoftheblue-collarworkforce
B.preserveblue–collarjobsforinternationalcompetition
C.acceleratemotor–canmanufacturinginHenryFord’sstyle
D.solvetheproblemofunemployment
3.Americanpoliticiansandlaborleaderstendtodislike_____.
A.confusioninmanufacturingeconomy
B.anincreaseinblue–collarworkforce
C.internalcompetitioninmanufacturingproduction
D.adropintheblue–collarjobopportunities
4.Theword“prescription”in“aprescriptionforunemployment”maybetheequivalentto______
A.somethingrecommendedasmedicaltreatment
B.awaysuggestedtoovercomesomedifficulty
C.somemeasurestakeninadvance
D.adevicetodire
5.Thispassagemayhavebeenexceptedfrom________
A.amagazineaboutcapitalinvestment
B.anarticleonautomation
C.amotor-carmagazine
D.anarticleonglobaleconomy
TEXTC
Therearetwofactorswhichdetermineanindividual'sintelligence.Thefirstisthesortofbrainheisbornwith.
Humanbrainsdifferconsiderably,somebeingmorecapablethanothers.Butnomatterhowgoodabrainhehas
tobeginwith,anindividualwillhavealoworderofintelligenceunlesshehasopportunitiestolearn.Sothe
secondfactoriswhathappenstotheindividual—thesortofenvironmentinwhichheisbroughtup.Ifan
individualishandicapped(不利)environmentally,itislikelythathisbrainwillfailtodevelopandhewillnever
attainthelevelofintelligenceofwhichheiscapable.Theimportanceofenvironmentindetermininganindividual'sintelligencecanbedemonstratedbythecasehistoryoftheidenticaltwins,PeterandMark.Beingidentical,thetwinshadidenticalbrainsatbirth,andtheirgrowthprocesseswerethesame.Whenthetwinswerethreemonthsold,theirparentsdied,andtheywere
placedinseparatefoster(抚养)homes.Peterwasraisedbyparentsoflowintelligenceinanisolatedcommunity
withpooreducationalopportunities.Markwasrearedinthehomeofwell-to-doparentswhohadbeentocollege.Hewasreadtoasachild,senttogoodschools,andgiveneveryopportunitytobestimulated
intellectually.Thisenvironmentaldifferencecontinueduntilthetwinswereintheirlateteens,whentheywere
giventeststomeasuretheirintelligence.Mark'sI.Q.was125,twenty-fivepointshigherthantheaverageand
fullyfortypointshigherthanhisidenticalbrother.Givenequalopportunities,thetwins,havingidenticalbrains,
wouldhavetestedatroughlythesamelevel.
11.Thisselectioncanbestbetitled____________.
A.MeasuringYourIntelligence
B.IntelligenceandEnvironment
C.TheCaseofPeterandMark
D.HowtheBrainInfluencesIntelligence
12.Thebeststatementofthemainideaofthispassageisthat_______.
A.humanbrainsdifferconsiderably
B.thebrainapersonisbornwithisimportantindetermininghisintelligence
C.environmentiscrucialindeterminingaperson'sintelligence
D.personshavingidenticalbrainswillhaveroughlythesameintelligence
13.Accordingtothepassage,theaverageI.Q.is_______.
A.85.B.100C.110D.125
14.Thecasehistoryofthetwinsappearstosupporttheconclusionthat_______.
A.individualswithidenticalbrainsseldomtestatthesamelevelB.anindividual'sintelligenceisdeterminedonlybyhisenvironment
C.lackofopportunityblocksthegrowthofintelligence
D.changesofenvironmentproducechangesinthestructureofthebrain
15.Thispassagesuggeststhatanindividual'sI.Q._______.
A.canbepredictedatbirth
B.staysthesamethroughouthislife
C.canbeincreasedbyeducation
D.isdeterminedbyhischildhood
