AnimalSentience2016.X:BrownCommentary2onKeyonFishPain
Fishpain:aninconvenienttruth
CommentaryonKeyonFishPain
CulumBrown
BiologicalSciences
MacquarieUniversity
Abstract:Whetherfishfeelpainisahotpoliticaltopic.Theconsequencesofourdenialare
huge given the billions of fish that are slaughtered annually for human consumption. The
economic costs of changing our commercial fishery harvest practices are also likely to be
great. Key outlines a structure-function analogy of pain in humans, tries to force that
templateontherestofthevertebratekingdom,andfails.Histargetarticlehassofarelicited
34 commentaries from scientific experts from a broad range of disciplines; only three of
these support his position. The broad consensus from the scientific community is that fish
mostlikelyfeelpainanditistimegovernmentsdisplaycourageenoughtoact.
Culum Brown [email protected] studies the
behavioural ecology of fishes with a special interest in
learning and memory. He is Associate Professor of
vertebrate evolution at Macquarie University, Co-Editor
ofthevolumeFishCognitionandBehavior,andEditorfor
Animal Behaviour of the Journal of Fish Biology.
https://sites.google.com/site/culumbrown/ Key(2016,2016a,2016b)hasputforthastructure-functionanalogyofpaininhumansand
thensetsouttodiscoverhowfaronemighttakethattemplatewhenappliedtotherestof
thevertebratekingdom–well,fishandtheoddrodentatanyrate.Morethan30
commentersrespondedtothearticleandthisclearlyshowsthatthistopicisstill
controversial.Ofthese,three(Rose;Hart;Diggles)supportKey’sposition.Thevastmajority
ofcommentaries,however,donot,andarguethatfishmostlikelyfeelpain.Mostagreethat
Key’sargumentisflawedatbestandhisevidenceofhowpainworksinhumansisselective,
simplistic,misleadingandoutdated(Damasio&Damasio;Merker;Panksepp;Shriver).One
emergingconsensus,however,isthatnosinglelineofscientificevidenceshouldover-rule
anyotherandmanyoftherespondentsagreethatbehaviouralstudies,suchasconditioned
placeaversion,areanimportantcomponenttounderstandingpaininhumanandnonhumanvertebratesalike.
TheprimarymessagefromthesecommentariesisthatKey’sargumentisfundamentally
flawedfromanevolutionaryperspective.Heargues(althoughlaterdeniesit)thathuman
brainarchitectureisrequiredtofeelpain.Themechanisticapproachcentresaroundthe
roleofthecortexinhumanpain.ButasDinets,Brown,Ngandotherspointout,thehuman
cortexhastakenonahugenumberofrolesthatoncewerethedomainofotherbrain
regions.Tosuggestthatfishdon’tfeelpainbecausetheylackacortexonewouldalsohave
towrite-offconsciousness(Seth)orindeedanycognitivefunctionthatoccursinthehuman
AnimalSentience2016.X:BrownCommentary2onKeyonFishPain
cortex.Oneexampleofapplyingthislogicwouldbetoconcludethatfisharenotcapableof
learningeither.Clearlythisargumentisabsurd(seeBrownetal2011;Brown2015for
reviews).Jones,Mather,Striedter,ElwoodandEdelmanallpointoutthatKey’sapproach
alsodeniesanypossibilityofconvergentevolution,butsurprisinglyKeyacceptsthatbirds
mightprovideanexampleofanindependentevolutionofacortex-likestructure.Haikonen,
Manzotti,andSethtakeitonestepfurtherandsuggestthatwedon’tevenunderstandpain
inhumansyetanditisfartooearlytobemakingjudgementcallsonothertaxa.Theroleof
thecortexinhumanpainisstilldebated(Stevens;Damasio&Damasio)andismostlikely
notthe“on-offswitch”forconsciousness(Segner).Waltersarguesthathighlevelsof
consciousnessarenotrequiredforpainperception,aviewwhichisconsistentwith
evolutionbeingagradualprocessratherthanoccurringasallornothingleapsandwiththe
notionthatpainislikelyanancientevolutionarytrait.
Broom,Sneddon&Brownstatedthattheseparationofnociceptionfromtheemotional
responsetoit(pain)isoldfashionedandsomewhatcounter-productive.Theyarguethat
nociceptionandpainarepartandparcelofthesamesystem,andgiventheimportant
natureofitsfunction(harmavoidance),thissystemislikelyevolutionarilyancient.Itshould
hardlybesurprisingifthissystemishighlyconservedacrossallvertebratesgiventhe
associatedfitnessadvantages(Seth;Striedter;Elwood).Thefactthatthebrainregionsthat
areresponsiblevaryacrosstaxaisconsistentwithwhatweknowtobethecasewithmany
otherbrainfunctions.
Digglesclaimsthatthecheerleadersoffishpainperception(andwelfaregenerally)
intrinsicallylinkpainwithwelfare.Herightlypointsoutthatothermeasuresofwelfareare
availableandarefarlesscontroversial.Ofcoursethereasonwearenottalkingaboutthese
othermeasureshereisbecausetheyhavebeenthefoundationoffishwelfarefordecades
(seeHuntingfordetal2006).Thereisnoargumenttobehadthere.Thequestionweare
addressinghereiswhetherfishfeelpainandwhetherweshouldincludeitinourwelfare
frameworkaswedowithothervertebrates.Everyoneagreesthatcurrentcommercial
harvestingmethodsarehighlystressfulforfish.Sadly,wecurrentlylackthepoliticalwillto
doanythingaboutit.Ihopethatgiventheknownrelationshipbetweenstresslevelsand
filetquality,theaquacultureindustrywillmovetolimitpainandstressinfishesinthe
absenceofanylegislation(i.e.,self-regulationdrivenbyeconomics).Unfortunately,Diggles
alsoneedsarefreshercourseinvertebrateevolutionsincehewronglystatesthatfishare
morecloselyrelatedtosharksthantheyaretomammalsandusesthatasabasisfor
likeningpaininfishtosharksratherthantomammals.Itistruethat“human-like”
nociceptorshavenotbeenidentifiedinelasmobranchsyet,butthatisnottosaythatthey
donotexist.Science101:Absenceofevidenceisnotevidenceofabsence.
Hartrightlypointsoutthatthereareissueswithterminologyandthathumansareselfobsessed.Frankly,Ithinkthewholeconsciousnessdebateisdistractingandisnotlikelyto
besolvedanytimesoon.Westilldon’treallyknowwhatitisorhowitisgeneratedin
humansletaloneinanimals.Nevertheless,recentpapers(e.g.,Reyetal2015)certainly
suggestthatfishareconsciousbeingsbasedonanycriteriacurrentlyinuse.Wadiwel
suggestsweshouldjustacceptthatwecannotexperiencewhatotheranimals(orpeople)
AnimalSentience2016.X:BrownCommentary2onKeyonFishPain
arefeelingandthatthequestionofpaininfishishenceoneofmakingcautiousethical
decisionsunderconditionsofuncertainty:theweightoftheevidenceforandagainstpainin
fish,andtheweightoftheconsequencesofafalsenegative(inferringfishdonotfeelpain
wheninrealitytheydo).
Thevastmajorityofcommentaries–expertsinawidespectrumofrelevantscientificand
ethicalspecialities--accepttheaccumulating,multi-disciplinaryevidencethatitislikelythat
fishfeelpain;moreover,eveninthecaseofthefence-sitters(includingoptimistic
agnostics),itisquiteapparentthattheprecautionaryprinciplesapply,giventhe
monumentalnumberoffishkilledeachyearincommercialfisheries.Indeed,Jonessuggests
thatsuchapositionisnotonlyprudent,butethicallyobligatory.Weshouldnotallow
conclusionsdrawnfromscientificevidencetobetaintedbythepotentialcommercial
consequences,asKeyseemstorecommend.
References
Balcombe,J.(2016)Cognitiveevidenceoffishsentience.AnimalSentience2016.X
Broom,D.M.(2016)Fishbrainsandbehaviourindicatecapacityforfeelingpain.Animal
Sentience2016.X
Brown,C.(2015).Fishintelligence,sentienceandethics.AnimalCognition,18,1–17
Brown,C.(2016).Comparativeevolutionaryapproachtopainperceptioninfishes.Animal
Sentience2016.X
Brown,C.Krause,J.&Laland,K.(2011).FishCognitionandBehavior2ndEdition.Oxford:
Wiley-Blackwell.Brown,C.(2015).Fishintelligence,sentienceandethics.Animal
Cognition,18,1–17
Dinets,V.(2016)Nocortexnocry.AnimalSentience2016.X
Elwood,R.W.(2016)Asinglestrandofargumentwithunfoundedconclusion.Animal
Sentience2016.X
Haikonen,P.O.(2016)Onthesentienceoffish.AnimalSentience2016.X
Hart,PaulJ.B.(2016)Fightingformsofexpression.AnimalSentience2016.X
Huntingford,F.A.,Adams,C.,Braithwaite,V.A.,Kadri,S.,Pottinger,T.G.,Sandøe,P.and
Turnbull,J.F.2006.Currentissuesinfishwelfare.J.FishBiol.,68:332–372.
Jones,R.C.(2016)Fishsentienceandtheprecautionaryprinciple.AnimalSentience2016.X
Key,Brian(2016).Whyfishdonotfeelpain.AnimalSentience2016.3
Key,Brian(2016a)Goingbeyondjust-sostories.AnimalSentience2016.X
Key,Brian(2016b)Falsifyingthenullhypothesisthat“fishdonotfeelpain"Animal
Sentience2016.X
Manzotti,R.(2016)Noevidencethatpainispainfulneuralprocess.AnimalSentience2016.X
Mather,J.A.(2016)Awiderviewofthepainproblemfromaninvertebrateperspective.
AnimalSentience2016.X
Merker,B.(2016)Drawingthelineonpain.AnimalSentience2016.X
AnimalSentience2016.X:BrownCommentary2onKeyonFishPain
Ng,Y.-K.(2016)Couldfishfeelpain?Acaseforawider,multi-facetedperspective.Animal
Sentience2016.X
Panksepp,J.(2016)Brainprocessesfor“good”and“bad”feelings:howfarbackin
evolution?AnimalSentience2016.X
Rey,S.,etal.(2015)."Fishcanshowemotionalfever:stress-inducedhyperthermiain
zebrafish."ProceedingsoftheRoyalSocietyofLondonB:BiologicalSciences
282(1819).
Segner,H.(2016)Whybabiesdonotfeelpain,or:Howstructure-derivedfunctional
intepretationscangowrong.AnimalSentience2016.X
Seth,A.K.(2016)Whyfishpaincannotandshouldnotberuledout.AnimalSentience
2016.X
Shriver,A.(2016)Cortexnecessaryforpain–notinthesensethatitmatters.Animal
Sentience2016.X
Sneddon,L.U.&Leach,M.C.(2016)Anthropomorphicdenialoffishpain.AnimalSentience
2016.X
Stevens,E.D.(2016)Whyisfish“feeling”paincontroversial?AnimalSentience2016.X
Striedter,G.(2016)Lackofneocortexdoesnotimplyfishcannotfeelpain.AnimalSentience
2016.X
Wadiwel,D.(2016)Fishandpain:thepoliticsofdoubt.AnimalSentience2016.X