研究生英语阅读教程Unit6.ppt

研究生英语阅读教程Unit6.ppt

《研究生英语阅读教程Unit6.ppt》由会员分享，可在线阅读，更多相关《研究生英语阅读教程Unit6.ppt（26页珍藏版）》请在冰豆网上搜索。

UnitSixIsItintheGenes?

ByArthurAllenQuestions1.Doyouagreethathumanbehaviorispredeterminedbygenes?

Whyorwhynot?

2.Whatcanaffectaparticulargenespotentialaccordingtothearticle?

3.Whatarefraternalandidenticaltwinsrespectively?

Whataretheirsimilaritiesanddifferences?

TextIn1993,aNationalCancerInstituteresearchernamedDeanHamermadewhatseemedtobeanastonishingdiscoveryaboutthegeneticsofhumanbehavior.HehadlocatedalinktomalehomosexualityontheXchromosome,HamerreportedinScience.Thestorywassplashedacrossfrontpagesaroundthecountry.Atlast,overlydotingmothersandearlycross-dressinggameswereoffthehookandthepredilectionsofeveryonefromWaltWhitmantoLiberacecouldbeexplainedbyafewerrantproteins.Hamersarticle,basedonanexaminationoftheDNAof40gaybrothers,ledtomass-marketbookdealsandminorcelebrity.Thereisonlyonesmall,underreportedglitch:

Hamersresultshaveneverbeenreplicated.Twosubsequentstudiesshowedmuchweakerevidenceofagaygene;athird,publishedonApril23butovershadowedbythemassacreatLittletonthedaybefore,foundnoevidenceatall.“Thereisnohintortrendinthedirectionoftheinitialobservation,”GeorgeEbers,aCanadianinvestigatorinvolvedinthestudy,saidinScience.mass-marketn.,adj,销售量大（的），畅销（的）vt,大量销售ern.Aquicktrawlthroughtheheadlinesofthe1990sfindsasimilarfateforotherfront-pagegeneticbreakthroughs.Despitemuch-publicizeddiscoveriesofgenesforschizophrenia,manic-depression,alcoholismandbipolardisorder,theprecisegeneticcomponentoftheseillnessescontinuetoeludescience.Thesamegoesforpersonalitytraits.Themuch-trumpeteddiscoveryofa“novelty-seekinggene”in1996hasntbeenreplicatednorhavevarious“depressiongenes”.Thisisnottosaythatprogressisntbeingmadeinparsingthebiologicalcomponentsofbehavior.Butinanygivenperson,theinterplayofgenesandtheenvironmentisahorrendouslycomplexstory.Individualgenesproducequitesubtleeffects,andthemorewelearnaboutDNA,thecleareritisthatanyparticulargenespotentialcanbeshutdownorenhancedbycomplexbiochemicalpathwayscontingentuponthingslikesleep,nutritionandstress.Bipolar:

adj.电双极的；两极地区的Bipolardisorderdepression医（状态与抑郁状态交替的）躁郁症（（亦作manic-depressiveillness）Adecadeagothefieldofbehaviorgeneticswasaflutterwiththehopethatmolecularbiologywouldhomeinonwhatmakeseachofustick.But“thefogisliftingveryslowly,”saysKennethKender,aprofessorofpsychiatricgeneticsatVirginiaCommonwealthUniversityinRichmond.“Wevelearnedthatinpsychiatricdisorders,therearenosinglegenesofreallylargeeffect.Iftherewere,wedhavefoundthemalready.”Genesforcertainconditions,suchasHuntingtonsorsicklecelldisease,areknownassimpleMendeliantraitsbecausetheyfollowthestraightforwardmodelofinheritancenotedbytheAustrianmonkGregorMendellastcentury.“Mendeliantraitsarelikeatrumpetcall.Thegeneticsignalblastsrightthrough,”saysKender.“Butthegeneticeffectsinmostbehavioraldisordersandtraitsarelikewhispersinabusytrainstation.Itshardtodistinguishthemfromthebackgroundnoise.”homeinon（靠信号、雷达等）导向目标追踪homeindustry本国工业;手工业生产;家庭工业homeinstruction家庭辅导homelandscape家庭园景Homeinonsth:

toaimormoveexactlytowardssth.对准某物,朝某物移动.ThatbehaviorisatrickybusinesstopredictwaselegantlydemonstratedbyanotherstudypublishedinSciencethismonth.Agroupofresearchersatthreeuniversities-inOregon,upstateNewYorkandEdmonton,Alberta-ranasetofidenticalexperimentsoneightdifferentmousestrains,eachbredtoshowdistinctbehavioralattributes.Theideawastoseewhethertheywouldactaccordingtotype.Theydidnt.Insometests,geneticallyidenticalmiceacteddifferentlydependedonthelabthattestedthem.Astrainofmicelackingareceptorfortheneurotransmitterserotonin-asubstancewhoseimbalancehasbeenimplicatedinvariousaddictionsandmooddisorders-wasexpectedtodrinkmorealcoholandshowmoreanxietythantheothermicestrains.Butallthreeteamsfoundthattheserotonin-mutantsdidntboozeitupanymorethantheothers.AndallstrainsofmicetestedinAlberta,itturnedout,weremellowerthantheNewYorkandOregonmice.Mustbetheweather,eh?

Geneticprogramming,inotherwords,isntnearlyasefficientasscientistsmighthope.PeterW.Nathanielsz,aCornellUniversityobstetricianwhoseresearchfocusesonthefetalenvironmentsofsheep,writesinanewbookthatsomeofthemostsignificantprogrammingofhumanhealth-andbehavior,potentially-occursinthewomb.Thisisntexactlyanewobservation,butadvancesinneurosciencehighlightthefactthatthemigrationofneuronstothepreciseareaofthebrainwheretheybelongduringpregnancyisadiceybusinessthatcanbeeasilydisrupted.Eveninahealthypregnancy,chancehasalargeimpactontheprenatalformationofthebrain.Eventwinswithidenticalsetsofgeneshavebrainsthatlookdifferent.Whathappensinthewombisoneofthenewfrontiersofthenature-nurturedebate.Epidemiologyhasalreadyshownhowimportantthewombcanbe.Overthepastseveraldecades,DavidBarkerofSouthamptonUniversityandotherresearchershavebeenstudyingtheoutcomeofthethousandsofDutchbabiesconceivedorcarriedduringthehungerwinterof19441945,whentheNaziskeptfoodfromreachingpeopleinAmsterdamandthesurroundingareatopunishtheDutch