Gotmilk?Ifyoudo,takeamomenttoponderthetrueoddnessofbeingabletodrinkmilkafteryou’reababy.   Nootherspeciesbuthumanscan.Andmosthumanscan’teither.   Thelonglistsoffoodallergiessomepeopleclaimtohavecanmakeitseemasifthey’rejustfinickyeaterstryingtorationaliz

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Gotmilk?Ifyoudo,takeamomenttoponderthetrueoddnessofbeingabletodrinkmilkafteryou’reababy.   Nootherspeciesbuthumanscan.Andmosthumanscan’teither.   Thelonglistsoffoodallergiessomepeopleclaimtohavecanmakeitseemasifthey’rejustfinickyeaterstryingtorationalizelikesanddislikes.Notso.Eggs,peanuts,treenuts,fish,shellfishsoyandglutenallcanwreakhavocontheimmunesystemofallergicindividuals,evencausingadeadlyreactioncalledanaphylaxis.   Butthoseallergicreactionsarerelativelyrare,affectinganestimated4%ofadults.   Milk’sdifferent.   Therearepeoplewhohavetruemilkallergiesthatcancausedeadlyreactions.Butmostpeoplewhohavebadreactionstomilkaren’tactuallyallergictoit,inthatit’snottheirimmunesystemthat’srespondingtothemilk.Instead,peoplewhoarelactoseintolerantcan’tdigestthemainsugar—lactose—foundinmilk.Innormalhumans,theenzymethatdoesso—lactase—stopsbeingproducedwhenthepersonisbetweentwoandfiveyearsold.Theundigestedsugarsendupinthecolon,wheretheybegintoferment,producinggasthatcancausecramping,bloating,nausea,flatulenceanddiarrhea.   Ifyou’reAmericanorEuropeanit’shardtorealizethis,butbeingabletodigestmilkasanadultisoneweirdgeneticadaptation.   It’snotnormal.Somewhatlessthan40%ofpeopleintheworldretaintheabilitytodigestlactoseafterchildhood.Thenumbersareoftengivenascloseto0%ofNativeAmericans,5%ofAsians,25%ofAfricanandCaribbeanpeoples,50%ofMediterraneanpeoplesand90%ofnorthernEuropeans.Swedenhasoneoftheworld’shighestpercentagesoflactasetolerantpeople.   Beingabletodigestmilkissostrangethatscientistssayweshouldn’treallycalllactoseintoleranceadisease,becausethatpresumesit’sabnormal,instead,theycallitlactasepersistence,indicatingwhat’sreallyweirdistheabilitytocontinuetodrinkmilk.   There’sbeenalotofresearchoverthepastdecadelookingatthegeneticmutationthatallowsthissubsetofhumanitytostaymilkdrinkersintoadulthood.   Along-heldtheorywasthatthemutationshowedupfirstinNorthernEurope,wherepeoplegotlessvitaminDfromthesunandthereforedidbetteriftheycouldalsogetthecrucialhormone(it’snotreallyavitaminatall)frommilk.   ButnowagroupatUniversityCollegeLondonhasshownthatthemutationactuallyappearedabout7,500yearsagoindairyfarmerswholivedinaregionbetweenthecentralBalkansandcentralEurope,inwhatwasknownastheFunnelBeakerculture.   ThepaperwaspublishedthisweekinPLOSComputationalBiology.   Theresearchersusedacomputertomodelthespreadoflactasepersistence,dairyfarming,otherfoodgatheringpracticesandgenesinEurope.   Today,thehighestproportionofpeoplewithlactasepersistenceliveinNorthwestEurope,especiallytheNetherlands,IrelandandScandinavia.ButthecomputermodelsuggeststhatdairyfarmerscarryingthisgenevariantprobablyoriginatedincentralEuropeandthenspreadmorewidelyandrapidlythannon-dairyinggroups.   AuthorMarkThomasofUniversityCollegeLondon’sdeptofGenetics,EvolutionandEnvironmentsays,“InEurope,asinglegeneticchange...isstronglyassociatedwithlactasepersistenceandappearstohavepeoplewithitabigsurvivaladvantage.”   TheEuropeanmutationisdifferentfromseverallactasepersistencegenesassociatedwithsmallpopulationsofAfricanpeopleswhohistoricallyhavebeencattleherders.   ResearchersattheUniversityofMarylandidentifiedonesuchmutationamongNilo-Saharan-speakingpeoplesinKenyaandTanzania.Thatmutationseemstohavearisenbetween2,700to6,800yearsago.TwoothermutationshavebeenfoundamongtheBejapeopleofnortheasternSudanandtribesofthesamelanguagefamilyinnorthernKenya. AccordingtothethirdsentenceofParagraph3,whichofthefollowingitemsisINCORRECT?

A.Anaphylaxis may cause people to die.
B.Eggs can damage all the allergic individuals’ immune system.
C.One who is allergic to gluten can not eat com.
D.Tuna may cause a person who is allergic to fish to die.
正确答案B
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