HEALTH
witha pairoffatyellowmiceknownas
Agoutimice(theOompaLoompaofthe
rodentkingdom),so calledbecausethey
carrytheAgoutigene,a particulargenethat
inadditiontomakingtherodentsyellow
andgivingthemanincreasedappetite,also
makesthemproneto canceranddiabetes).
Jirtleandhisteamseparatedthemiceinto
twogroupsandfedonegroupofpregnant
Agoutimicea dietrichinBvitamins(folic
acidandVitaminB12).
Theothergeneticallyidenticalgroup
werenotgivenanyprenatalnutrition.The
parentmicefedthediethighinmethyl-rich
Bvitaminsproducedmicethatwereslender
andmousybrown,ratherthanfatand
yellow.Theydidnotdisplaytheirparent’s
susceptibilitytocanceranddiabetesand
livedtooldage.TheeffectoftheAgoutigene
hadbeenvirtuallyerased,withoutDNA
change,andwithdiet.Whenexamined,
it wasdiscoveredthatthemothershad
passedontheAgoutigenebutthanksto
theirmethyl-richpregnancydiet,theyhad
addeda chemicalswitch(an epigenome)to
thegenethatsquasheditsnegativeeffects.
Theresearchershadproventhat
nutritionalchangeinthedietofmothers
couldaffectthegeneexpressionoftheir
children.Themessagehere—if you’retall
andthin,ringyourmothertothankher...
(no,itsnotquitethatsimple,butthefact
remains:thedietofyourmotherwhile
pregnanthasalreadyinfluencedthefate
of yourhealthspanandlongevity).OK,
soyourbodymayhavebeengoverned
byMum’seatinghabits,butsurelyyour
personalitytraitswerebeenbuiltingenetic
stoneatconceptionandcannotbetweaked?
Thinkagain.Intheirfamousresearch
paperpublishedin2004,DoctorsMoshe
SzyfandMichaelMeaneyprovedsomething
incredible:epigeneticprogrammingwasalso
possibleafterbirthandcouldbechanged
bymaternalbehaviour.It’sMum’sfault
(again...).Meaneycomparedtwotypes
ofrats:thosewhopatientlylickedtheir
offspringtonurturethemafterbirthand
thosethatneglectedtheirnewborns.The
lickednewbornsgrewuptobecomparatively
braveandrelaxed(for rats).Theneglected
newbornsgrewintonervousskittishrodents
whoranforthedarkestcornerwhenplaced
ina newenvironment.Theresearchersthen
analysedthebraintissueofboththelicked
andnon-lickedratsandfounddifferentDNA
methylationpatternsinthebraincellsof
eachgroup.Amazingly,themother’slicking
activityresultedinthesuppressionofa gene
involvedinstressresponse.
Putsimply,themotherswhowere
attentiveandnurturingtotheiroffspring
changed their pup’s response to stress for life,
makingthemcalmerandaschilledoutasa
labmousecanbe,provinga littlelovegoes
a longway,andthatwhileDNAremains
thesame,psychologicalandbehavioural
tendenciesareformedbyexperienceand
epigenetics.You’llneverlookatMumthe
samewayagain.Todemonstratethatthe
effectsoftheexperimenthadnobasisin
genetics,thescientiststookratpupsbornto
inattentivemothersandgavethemattentive
ones,andviceversa.Aspredicted,therats
borntoattentivemothersbutraisedby
neglectfulonesgrewuptobestressedand
nervous,whilethoseborntobadmothers
butraisedbygoodonesgrewtobecalm
andbrave,whichalsoprovidesaninteresting
insightintotheworldoffosterfamiliesand
adoptiveparents.
Worringly,anotherstudyhasdetermined
thatthisepigeneticchangecanlastforseveral
generations.Researchersexposedmale
miceto 10 daysofbullyingbylarger,more
aggressivemice,resultinginthebulliedmice
beingsociallywithdrawn.Theythentook
thatgroupofbulliedmiceandbredthem
withfemales,butkeptthemfrommeeting
theiroffspring.Despitehavingnocontact
withtheirfathers,theoffspringofthebullied
micewerehypersensitivetostressandhad
depressivetendencies.Inheritedpersonality
wasalteredthroughepigeneticchangeover
generations.Sofar,thedefinitivestudieshave
onlyinvolvedrodents,butresearchersare
constantlyfindingevidencetosuggestthat
epigeneticinheritanceisatworkinhumans
too.Theenvironmentandatmosphereof
childhoodcanshapeusforever,downto
theepigeneticcore.
Exposuretotoxinsandforeignchemicals
canalsoworktoalterourgeneticexpression.
In2004,geneticistMichaelSkinner
accidentlydiscoveredanepigeneticeffect
inratsthatlastedatleastfourgenerations.
Hewasstudyinghowa commonlyused
agriculturalpesticide,whenintroducedto
pregnantrats,affectedthespermcountof
malepups.Thesurprisecamewhenhetested
themaleratsinsubsequentgenerations
—thegrandsonsoftheexposedmothers.
Althoughthepesticidehadnotchanged
DNAcoding,thesecond-generation
offspringalsohadlowspermcounts.The
samewastrueofthenexttwogenerations.
Itturnsoutthatyoumaynothaveyour
mothertoblameforeverythinganda scroll
throughyourancestry.comfamilytreecould
providetherealvillainofthegeneticstory.
Subjectingmalelabratstoendocrine-
disruptingchemicalshasalsoproduced
behaviouraleffectsintheiroffspring,even
whenthetoxinexposurehappenswellbefore
mating.Manystudieshavebeendoneonthe
common chemical bisphenol-A (otherwiseknownas BPA)foundin plasticwaterbottles
andfoodstoragecontainers.Thischemical
altersDNAmethylationandappearsto
effectlearning,memoryandbehaviourinthe
childrenofparentsexposed.Wealsoknow
thatwhenmalemiceandratsareexposed
toalcoholbeforemating,theiroffspring
dobadlyatdiscriminationonspatialtasks,
theyaremoreaggressiveanddisplaymore
anxiety-likebehaviourthanoffspringof
unexposedanimals.Malesexposedto
cocainehaveoffspringwithsmallerbrains
anddeficitsinattentionspanandworking
memory.Inallexamples,epigeneticchanges
havebeennoted.Itmayseembizarre,but
nowtheresponsibilityrestswithYOU—
whatyoueat,smokeordotodaycouldaffect
notonlyyourhealth,butalsothehealthand
behaviourofyourgreat-grandchildren.
TheDNAmayremainthesame,but
justasyouhaveinheritedyourgrandfather’s
hairylegsandanxious-dispositioncausedby
neglecthesufferedasa baby,yourgrandchild
mayendupdetestingthesmallerbrainand
lackofattentionspanhandeddownthrough
epigeneticchangescausedbyyourhabitual
‘weekendwarrior’behaviour.Stayin this
Saturdaynight...notforyou,butforyour
great-grandchildren.
Moreandmore,researchersarefinding
thatanextrabitofa vitamin,a brief
exposuretoa chemical,evenanaddeddose
ofmaternallovecanaltertheepigenome
—andtherebychangethesoftwareofour
genes.Interestingly,wearediscoveringthat
evencommonhealthadvicelikeexercising
maywork(at leastin part)by affectingthe
expressionofourgenes.Certaintypesof
stemcellscan ‘choose’howtheydifferentiate,
andexerciseandenvironmentalfactorscan
actuallydeterminethedirectionthatcells
takeearlyintheirdevelopment.Whenmice
ranona treadmillforaslittleasanhourthree
timesa week,theexerciseepigenetically
encouragedthesestemcellstobecome
blood-producingcellsofthebonemarrow,
ratherthanfatcells.Thestemcellsofthe
sedentarymicestudiedweremuchmore
likelytobecomefatcells,meaningthat
exercisehastheabilitytoimpactbiology
andepigenetics.Itturnsoutthatweare
notcompletelyatthemercyofourgenes.
Inmanyways,theyareatthemercyofour
healthandlifestylechoices—weholdthe
powerofgeneticfateinoursweatypalm.
Andbrainpower?Researchershave
previouslyshownthata person’sIQishighly
influencedbygeneticfactorsandhaveeven
identifiedcertaingenesthatplaya role.
They’vealsoshownthatapproximately62%
ofindividualacademicperformancehas
a basisingeneticfactors...butit isnotall
about a Mensa-level IQ. A study of more than