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.

-----Tinahadnothingforbreakfast,____________she?

-----_____________.Shehadsomebreadandmilk.

-----Wouldyoumindmyusingyourpen?

-----_______________.

Isthere______________totellus?No,nothing.

1.AEuropeanspacecrafttookofftodaytospearheadthesearchforanother"Earth"amongthestars.

2.TheCorotspacetelescopeblastedoffaboardaRussianSoyuzrocketfromtheBaikonurcosmodromeinKazakhstanshortlyafter2.20pm.

3.Corot,shortforconvectionrotationandplanetarytransits,isthefirstinstrumentcapableoffindingsmallrockyplanetsbeyondthesolarsystem.Anysuchplanetsituatedintherightorbitstandsagoodchanceofhavingliquidwateronitssurface,andquitepossiblylife,althoughaleadingscientistinvolvedintheprojectsaiditwasunlikelytofind"anylittlegreenmen".

4.DevelopedbytheFrenchspaceagency,CNES,andpartneredbytheEuropeanSpaceAgency(ESA),Austria,Belgium,Germany,BrazilandSpain,Corotwillmonitoraround120,000starswithits27cmtelescopefromapolarorbit514milesabovetheEarth.Overtwoandahalfyears,itwillfocusonfivetosixdifferentareasofthesky,measuringthebrightnessofabout10,000starsevery512seconds.

5."Atthepresentmomentwearehopingtofindoutmoreaboutthenatureofplanetsaroundstarswhicharepotentialhabitats.Wearelookingathabitableplanets,notinhabitedplanets.Wearenotgoingtofindanylittlegreenmen,"ProfessorIanRoxburgh,anESAscientistwhohasbeeninvolvedwithCorotsinceitsinception,toldtheBBCRadio4Todayprogramme.

6.ProfRoxburghsaiditwashopedCorotwouldfind"rockyplanetsthatcoulddevelopanatmosphereand,iftheyaretherightdistancefromtheirparentstar,theycouldhavewater".

7.Tosearchforplanets,thetelescopewilllookforthedimmingofstarlightcausedwhenanobjectpassesinfrontofastar,knownasa"transit".Althoughitwilltakemoresophisticatedspacetelescopesplannedinthenext10yearstoconfirmthepresenceofanEarth-likeplanetwithoxygenandliquidwater,Corotwillletscientistsknowwheretopointtheirlenses.

8.MeasurementsofminutechangesinbrightnesswillenablescientiststodetectgiantJupiter-likegasplanetsaswellassmallrockyones.Itistherockyplanets-thatcouldbenobiggerthanabouttwicethesizeoftheEarth-whichwillcausethemostexcitement.Scientistsexpecttofindbetween10and40ofthesesmallerplanets.

9.Corotwillalsoprobeintostellarinteriorsbystudyingtheacousticwavesthatrippleacrossthesurfaceofstars,atechniquecalled"asteroseismology".

10.Thenatureoftheripplesallowsastronomerstocalculateastar’sprecisemass,ageandchemicalcomposition.

11."Aplanetpassinginfrontofastarcanbedetectedbythefallinlightfromthatstar.Smalloscillationsofthestaralsoproducechangesinthelightemitted,whichrevealwhatthestarismadeofandhowtheyarestructuredinternally.Thisdatawillprovideamajorboosttoourunderstandingofhowstarsformandevolve,"ProfRoxburghsaid.

12.Sincethediscoveryin1995ofthefirst"exoplanet"-aplanetorbitingastarotherthantheSun-morethan200othershavebeenfoundbyground-basedobservatories.

13.Untilnowtheusualmethodoffindingexoplanetshasbeentodetectthe"wobble"theirgravityimpartsonparentstars.ButonlygiantgaseousplanetsbiggerthanJupitercanbefoundthisway,andtheyareunlikelytoharbourlife.

14.Inthe2010s,ESAplanstolaunchDarwin,afleetoffourorfiveinterlinkedspacetelescopesthatwillnotonlyspotsmallrockyplanets,butanalysetheiratmospheresforsignsofbiologicalactivity.

15.Ataroundthesametime,theUSspaceagency,Nasa,willlaunchTerrestrialPlanetFinder,anotherspacetelescopedesignedtolocateEarth-likeplanets.

ChoosetheappropriateletterfromA-Dforquestion1.

1.Corotisaninstrumentwhich

(A)canhelptosearchforcertainplanets

(B)isusedtofindplanetsintheorbit

(C)canlocateplanetswithhumanbeings

(D)canspotanyplanetswithwater.

Dothefollowingstatementsagreewiththeinformationgiveninthereadingpassage?Forquestions2-5write

TRUEifthestatementagreeswiththeinformation

FALSEifthestatementcontraictstheinformation

NOTGIVENifthereisnoinformationonthisinthepassage

2.Scientistsaretryingtofindoutabouttheplanetsthatcanbeinhabited.

3.BBCRadio4recentlyfocusesonthebroadcastingofCorot.

4.Passingobjectsmightcauseafallinlight.

5.CorotcantellwhetherthereisanotherEarth-likeplanet.

Basedonyourreadingofthepassage,completethesentencesbelowwithwordstakenfromthepassage.UseNOMORETHANTHREEWORDSforeachanswer.

Withmeasurements,scientistswillbeabletosearchforsomegaseousandrockyplanets.Theywillbeextremelyexcitediftheycandiscoversomesmall6.__________,theexpectednumberofwhichcouldbeupto7.__________.

Corotwillenablescientiststostudythe8.__________ofstars.Inthisway,astar’smass,ageandchemicalcompositioncanbecalculated.

AccordingtoProfRoxburgh,changesinlightcanbecausedbypassingplanetsorstar9.__________.Therelatedstatisticscangainusabetter10.__________ofthestarformationandevolvement.

Observatorieshavefoundmanyexoplanets,whichare11.__________otherstarsthantheSun.Thecommonwayusedinfindingexoplanetscanonlydetecthugegasplanets,whichdonot12.___________.

WiththelaunchingofDarwin,astronomerswillbeabletoanalysewhetherthoserockyplanetshave13.__________forlife.