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经济学人完整整理版DigestOfThe.Economist.2006(8-9)ThemismeasureofwomanMenandwomenthinkdifferently.ButnotthatdifferentlyINTHE1970stherewasafadforgivingdollstobabyboysandfire-enginestobabygirls.Theideawasthatdifferencesinbehaviourbetweenthesexesweresolelytheresultofupbringing:cultureturnedwomenintoironers,knittersandchatterboxes,andmenintohammerers,drillersandsilenttypes.Switchingtoyswouldputanendtosexualsorting.Today,itisclearwhyitdidnot.Whenboysandgirlsareborn,theyarealreadydifferent,andtheyfavourdifferenttoysfromthebeginning.Thatboysandgirls—andmenandwomen—areprogrammedbyevolutiontobehavedifferentlyfromoneanotherisnowwidelyaccepted.Surely,noonetodaywouldthinkofdoingwhatJohnMoney,ofJohnsHopkinsUniversity,didin1967:amputatingthegenitaliaofaboywhohadsufferedabotchedcircumcision,andadvisingtheparentstobringhimupasagirl.Theexperimentdidn'twork,andtheconsequencesweretragic.Butwhichofthedifferencesbetweenthesexesare“biological”,inthesensethattheyhavebeenhonedbyevolution,andwhichare“cultural”or“environmental”andmightmoreeasilybealteredbychangedcircumstances,isstillfiercelydebated.ThesensitivityofthequestionwasshownlastyearbyafuroreatHarvardUniversity.LarrySummers,thenHarvard'spresident,causedastormwhenhesuggestedthatinnateabilitycouldbeanimportantreasonwhythereweresofewwomeninthetoppositionsinmathematics,engineeringandthephysicalsciences.Evenasapropositionfordiscussion,thisisunacceptabletosome.Butbiologicalexplanationsofhumanbehaviouraremakingacomebackasthegenerationofacademicsthatfearedthemasacovertwayofjustifyingeugenics,orofthwartingMarxistutopianism,isretiring.Thesuccessofneo-Darwinismhasprovidedanintellectualunderpinningfordiscussionaboutwhysomedifferencesbetweenthesexesmightbeinnate.Andnewscanningtechniqueshaveenabledresearcherstoexaminethebrain'sinteriorwhileitisworking,showingthatmaleandfemalebrainsdo,atonelevel,operatedifferently.Theresults,however,donotalwayssupportpastclichésaboutwhatthedifferencesinquestionactuallyare.Differencesinbehaviourbetweenthesexesmust,insomeway,bereflectionsofsystematicdifferencesbetweenthebrainsofmalesandfemales.Suchdifferencescertainlyexist,butdrawinginferencesfromthemisnotaseasyasitmayappear.Forastart,men'sbrainsareabout9%largerthanthoseofwomen.Thatusedtobecitedasevidenceofmen'ssupposedlygreaterintelligence.Actually,thedifferenceislargely(andprobablycompletely)explainedbythefactthatmenarebiggerthanwomen.Inrecentyears,moredetailedexaminationhasrefinedthepicture.Femalebrainshaveahigherpercentageofgreymatter(themanifestation,enbloc,ofthecentralbodiesofnervecells),andthusalowerpercentageofwhitematter(themanifestationofthelong,thinfilamentsthatconnectnervecellstogether),thanmalebrains.That,plusthefactthatinsomeregionsofthefemalebrain,nervecellsarepackedmoredenselythaninmen,meansthatthenumberofnervecellsinmaleandfemalebrainsmaybesimilar.Oddly,though,themainconnectionbetweenthetwohemispheresofthebrain,whichisknownasthecorpuscallosumandismadeofwhitematter,isproportionatelysmallerinmenthanwomen.Thismayexplainwhymenuseonlyonesideofthebraintoprocesssomeproblemsforwhichwomenemploybothsides.ThesedifferencesinstructureandwiringdonotappeartohaveanyinfluenceonintelligenceasmeasuredbyIQtests.Itdoes,however,seemthatthesexescarryoutthesetestsindifferentways.Inoneexample,wheremenandwomenperformequallywellinatestthatasksthemtoworkoutwhethernonsensewordsrhyme,brainscanningshowsthatwomenuseareasonboththerightandtheleftsidesofthebraintoaccomplishthetask.Men,bycontrast,useonlyareasontheleftside.Thereisalsoacorrelationbetweenmathematicalreasoningandtemporal-lobeactivityinmen—butnoneinwomen.Moregenerally,menseemtorelymoreontheirgreymatterfortheirIQ,whereaswomenrelymoreontheirwhitematter.AmericanexceptionalismTheworld'sbiggestinsurancemarketistoosplinteredKANSASCITY,Missouri,isknownmoreforitshistoricalroleasacattletownthanasafinancialhub.Butitistothismidwesterncity,America's26thlargest,thatregulatorsandinsuranceexecutivesfromaroundtheglobeheadwhentheywanttomakesenseoftheworld'slargest—andoneofitsweirdest—insurancemarkets.ForitisinKansasCitythattheNationalAssociationofInsuranceCommissioners(NAIC)ishoused.Itoverseesamarketaccountingforone-thirdofpremiumswrittenworldwide.OutsideKansasCity,themarketbecomesaregulatoryfree-for-all.EachofAmerica's50states,plustheDistrictofColombia,governsitsinsuranceindustryinitsownway.Inanincreasinglyglobalinsurancemarket,America'sstate-basedsystemiscomingunderstrongpressuretoreform.InsurancehaschangeddramaticallysincetheNAICwassetupin1871,withgrowingsophisticationinunderwritingandriskmanagement.PremiumsinAmericahaveballoonedto$1.1trillionandmarketpowerisincreasinglyconcentratedinthehandsofbigplayers(someofthemforeign-owned)thatarepushingforanoverhaulofthestate-basedsystem.“It'sanextremelyexpensiveandByzantineprocess,”saysBobHartwig,aneconomistwiththeInsuranceInformationInstitute,aresearchgroup.Thoughafiercelypoliticalissue,congressionalsupportforsimplifyingthesystemisgainingground.BothhousesofCongressarelookingatproposalstochangethestate-basedsystem.Biginsurersfavouraversionthatwould