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1、www.ks5u.com专题限时训练(三十七) [科普知识型阅读理解(一)](限时：25分钟) (一)DNAleftatacrimescenecouldbeusedinthefuturetobuildupapictureofanoffender'sface,whichwasrevealedtonight.AfirststeptowardsgeneticmugshotshasbeentakenbyresearchersintheUSwholinkspecificDNAmarkerswithfaceshapes.Toidentifythegenes,theyf
2、ocusedonknownmutations(突变)thatcausechangesofthefaceandhead.Normalversionsofthesegeneswerefoundtoinfluenceindividualfeatures.Forinstance,onegeneaffectedthelips,anothertheshapeandconfigurationofbonesaroundtheeyes,andathirdtheappearanceofthemidfaceandskull.Intotal,20geneshad“significanteffects”onfa
3、cialappearance.LeadscientistProfessorMarkShriver,fromthePennsylvaniaStateUniversity,said,“WeuseDNAtomatchtoanindividualoridentifyanindividual,butwecangetsomuchmorefromDNA.Currentlywecan'tgofromDNAtoaface,orfromafacetoDNA,butitshouldbepossible.”Theimplicationsarefarreaching,raisingthepossibilityo
4、fcreatingadatabankoffacialtypesbasedongeneticmarkers.DNAfromacrimescenecouldthenbeusedtoproducearoughimageofthefaceofanoffenderorvictim.Suchgeneticmugshotsmaybemorereliablethancomputergenerated“Efits”basedonwitnesses'memory.Otherusesofthetechniquemightincludeprovingtheidentitiesoffathersinpatern
5、itycases,orvisualizingourremoteancestorsfromfossilDNA.ThescientistswroteintheonlinejournalPublicLibraryofScienceGenetics，“Suchpredictivemodellingcouldbeforensicallyuseful.Forexample,DNAleftatcrimescenescouldbetestedandfacescouldbepredictedinordertohelptonarrowthepoolofpotentialsuspects.Further,o
6、urmethodscouldbeusedtopredictthefacialfeaturesofdescendants,deceasedancestors,andevenextincthumanspecies.Inaddition,thesemethodscouldprovetobeusefuldiagnostictools.”TheteamdevelopedamodelwhichfirstestablishedarangeofphysicalfaceshapesfrompeopleofmixedWestAfricanandEuropeanancestryfromtheUS,Brazi
7、landCapeVerde.Measurementsweretakenofthousandsofpointcoordinatesongridsplacedover3Dimagesofthefaces.Statisticalmethodswerethenusedtodeterminetherelationshipbetweenfacialdifferencesandtheeffectsofgenders,ethnicancestryandindi
