Early cessation of ceramic production for ancestral Polynesian society in Tonga

15 Pages·2017·2.34 MB·English

RESEARCHARTICLE
Early cessation of ceramic production for
ancestral Polynesian society in Tonga
DavidV.Burley1*,SeanP.Connaughton2☯,GeoffreyClark3☯
1 DepartmentofArchaeology,SimonFraserUniversity,Burnaby,BC,Canada,2 InlailawatashLimited
Partnership,NorthVancouver,BC,Canada,3 SchoolofCulture,History&Language,AustralianNational
University,Canberra,Australia
☯Theseauthorscontributedequallytothiswork.
*[email protected]
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Abstract
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AncestralPolynesiansocietyistheformativebasefordevelopmentofthePolynesiancul-
turaltemplateandproto-Polynesianlinguisticstage.EmerginginwesternPolynesiaca
2700calBP,itiscorrelatedinthearchaeologicalrecordofTongawiththePolynesianPlain-
wareceramicphasepresentlythoughttobeofapproximately800yearsdurationorlonger.
OPENACCESS Herewere-establishtheupperboundaryforthisphasetonomorethan2350calBP
Citation:BurleyDV,ConnaughtonSP,ClarkG employingasuiteof44newandexistingradiocarbondatesfrom13PolynesianPlainware
(2018)Earlycessationofceramicproductionfor
siteoccupationsacrosstheextentofTonga.Theimplicationsofthisboundary,theabrupt-
ancestralPolynesiansocietyinTonga.PLoSONE
nessofceramicloss,andtheshorteningofdurationto350yearshavesubstantiveimplica-
13(2):e0193166.https://doi.org/10.1371/journal.
pone.0193166 tionsforarchaeologicalinterpretationsintheancestralPolynesianhomeland.
Editor:SergiLozano,InstitutCatalàde
PaleoecologiaHumanaiEvolucio´Social(IPHES),
SPAIN
Received:September18,2017
Introduction
Accepted:February6,2018
Thepresenceofceramicvesselsinthearchaeologicalrecordtypicallyisviewedasatechnologi-
Published:February23,2018
caldevelopmentwithhighfunctionality,atechnologyconcurrentwithsedentismandagricul-
Copyright:©2018Burleyetal.Thisisanopen
turalproduction,andamarkerforincreasingculturalcomplexity.Itseemsaberrant,then,that
accessarticledistributedunderthetermsofthe
asocietycouldorwouldabandonarobustpottingindustrywithoutapparentreason.Suchwas
CreativeCommonsAttributionLicense,which
permitsunrestricteduse,distribution,and thecaseinthePolynesianhomelandofTongawhereLapitacolonizergroupsof2850calBP
reproductioninanymedium,providedtheoriginal producedarangeofbothdecoratedandplainceramicvesselforms.Withinaperiodof
authorandsourcearecredited. approximately150years,thedecoratedvesselformsdisappearedcompletelywiththepotting
DataAvailabilityStatement:Allrelevantdataare industrythenfocusedonamorelimitedrangeofundecoratedtypes.Ultimatelytheseceased
withinthepaperanditsSupportingInformation tobemade,withceramicmanufactureabsentinallPolynesiansocietiesatthetimeofEuro-
files. peancontact.Kirch[1]rightfullynotesthatthistypeofceramicsequenceruns“...backwards
Funding:Fundingforthisstudywasprovidedby fromwhatwehavebecomeaccustomedtoseeinginmostpartsoftheworld”.
theSocialSciencesandHumanitiesResearch Inthispaper,weaddressthetimingforceramicproductionlossinthearchaeological
CouncilofCanada,www.crsh.ca,file435-2013- recordofTonga.TheislandofTongatapuinsouthernTongawasthefirstPolynesianisland
0566andgrantno.435-2012-0194toDVB,andan
grouptobecolonizedbyLapitapeoples,anditisfromherethatinitialsettlementthroughout
AustralianResearchCouncilDiscoveryGrant(AU),
mostoftheancestralPolynesianhomelandemanated(Fig1).Ourdataincorporateavolume
grantno.DP160103778toGC.Thefundershadno
of44existingandnewradiocarbondatesforthePolynesianPlainwarephaseinTongaas
roleinstudydesign,datacollectionandanalysis,
decisiontopublish,orpreparationofthe recoveredfrom13sitesacrossthearchipelago.ThePolynesianPlainwarephaseisthepost-
PLOSONE|https://doi.org/10.1371/journal.pone.0193166 February23,2018 1/15
LossofceramicsinTonga
manuscript.SeanP.Connaughtonisemployedby
InlailawatashLimitedPartnership.Inlailawatash
LimitedPartnershipprovidedsupportintheform
ofsalaryforauthorSPC,butdidnothaveany
additionalroleinthestudydesign,datacollection
andanalysis,decisiontopublish,orpreparationof
themanuscript.Thespecificroleofthisauthoris
articulatedinthe‘authorcontributions’section.
Competinginterests:SeanP.Connaughtonis
employedbyInlailawatashLimitedPartnership.
Therearenopatents,productsindevelopmentor
marketedproductstodeclare.Thisdoesnotalter
ouradherencetoallthePLOSONEpolicieson
sharingdataandmaterials.
Fig1.Mapofislandswithintheancestral,WestPolynesianhomeland.Twoadditionalislands,FutunaandAlofi,arenot
includedonthemapbeing300kmnorthwestofNiuafo’ou.TheoutliersofNiuafo’ouandNiuatoputapuarepartof
traditionalandcontemporaryTonga.
https://doi.org/10.1371/journal.pone.0193166.g001
Lapitatemporalintervaldefinedbyplainceramicwaresbutmodeledasaninstrumental
periodfortheemergenceofPolynesiansociety[2].Ratherthanlongtermgraduallossofthe
industrywhereceramicwaresbecomeincreasinglysimplifiedanddegraded,orwherethetim-
ingforceramiclossacrosstheTongangroupisvaried,thedataareuniforminillustratingthis
eventtobeearlyandcontemporaneousthroughoutthearchipelago.Incontrasttomostifnot
allcurrentinterpretations,thePolynesianPlainwarephaseisalsoshortinduration.Theimpli-
cationsoftheseresultsforourunderstandingoftheconceptualframeworkforancestralPoly-
nesiansociety,theTonganpast,andTonga’spositionwithinwesternPolynesianantiquityare
examined.
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LossofceramicsinTonga
Context
Tonganarchaeologyhasalonghistoryofarchaeologicalpracticewithacriticalemphasis
placedonquestionsrelatedtofirstsettlement.Relativetothis,Burleyhasbeeninvolvedina
quartercenturyplusresearchprogramonPolynesianoriginsinTongawherearchaeological
surveyandexcavationshavebeencarriedoutwithineachofthethreeprincipalislandgroups–
Tongatapu,Ha’apaiandVava’u.InitiallandfallbypeoplewithdistinctiveLapitaceramicstook
place~2850calBPattheentrancetothelagoonsystemoffthenortheastcoastofTongatapu
[3],[4].HighprecisiondatesfromU/Thmeasurementofacroporacoraltools,AMSradiocar-
bondatesonshort-livedwoodcharcoalsandBayesianmodelingwithotherradiocarbondates
provideclearinsightintothetimingofsubsequentpopulationmovements[5].Afteralag
intervalonTongatapuof70–90years,occupationexpansionintothecentralHa’apaiislands
occurredbetween2772and2759calBPwithalmostsimultaneousmovementnorthwardinto
theVava’ugroupbetween2805and2760calBP.WepresumeLapitaoccupationofthefar
northernoutlierofNiuatoputapuandSamoawereextensionsofthismovement.Importantly
forthispaper,Bayesianmodelingofdatedsamplesprovideanestimateddurationforthe
Lapitaceramicphaseineachgroup.ThisincludesenddatesonTongatapuof2703–2683cal
BP(duration129–158years),onHa’apaiof2728–2716calBP(duration32–49years)andon
Vava’uof2709–2680calBP(duration51–82years)[5].Theenddatessimultaneouslydefine
thebeginningofthesequentPolynesianPlainwarephaseforeachgroup,hereaftergeneralized
as2700calBP.
TheadditionofPolynesianinreferencetoapost-Lapitaphasecharacterizedbyundeco-
ratedceramicsinTongaandSamoaisattributabletoGreen[6],[7].Inkeepingwithargu-
mentsbyGroube[8]thatPolynesiansdidnotcomefromanywherebut“became”Polynesian,
GreenequatedtheonsetofPolynesianethnogenesiswiththelossofdecoratedLapitawares.
Polynesianwasaddedtoplainwarestodenotethisassociation.KirchandGreen[2]providea
substantiveanalysisofancestralPolynesianculture,integratingarchaeology,linguistics,ethno-
graphiccomparisonandbiologicalanthropology.PolynesianPlainwareceramicscontinueto
beidentifiedasimportantcorrelateswithinthisprocess,particularlyasregionalvariationsin
ceramicassemblagesmightreflectuponlinguisticdivergencesbetweenislandgroupsthrough-
outWestPolynesia.KirchandGreen[2]furtherinterprettheendofpotterymanufactureas
concomitantwith“thebreak-upofAncestralPolynesianculture”andthemovementofgroups
intothePolynesianoutliersandcentralEastPolynesia.IntheKirchandGreen[2]scenario,
thePolynesianPlainwarephasewouldhavesubstantialtimedepthextendingfromterminal
LapitaintoatleasttheinitialcenturiesoftheChristianera.ThedurationofthePolynesian
PlainwarephaseindifferentareasacrossWestPolynesiaisexpectedtobevaried;insome
areaspotteryproductionisarguedtohavecontinuedwellintolaterprehistory[9],[10].Con-
naughton[11]acknowledgesthisinhisregionalreviewofPolynesianPlainwarephasedates
forwesternPolynesiabutgoesontoprojectageneraldurationlasting1200–1300yearsafter
thelossofdecoratedvessels.
TheBayesiananalysisofTongan14CandU/Thdatesdescribedabovewassuccessfulinpro-
ductionofahighprecisionchronologyforfirstLapitasettlementandexpansion.Asimilar
efforttoapplyBayesianmodelingtothenexistingPolynesianPlainwaredateswaslessreward-
ing.VeryfewacceptablePlainwaredatesexistedforTongatapu(n=3)orVava’u(n=2)and
alldates,includingthoseforHa’apai(n=14),fellwithinasegmentoftheradiocarboncalibra-
tioncurvereferredtoastheHallstattPlateau[12].Thelatterisaflatteninginthecurvethat
homogenizescalibrationoutputstoaroughly300-yearinterval(Fig2).TheHa’apaidatesdid
implyashortdurationforthePolynesianPlainwarephase.Skepticismovertheiraccuracynev-
erthelessleft“openthequestionofaboundaryend”[5].Thisskepticismwasinpartaconcern
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LossofceramicsinTonga
Fig2.TheHallstattPlateau(shaded)asconstructedontheOxCalradiocarboncalibrationprogramforthe
southernhemisphere2013(SHcal13)calibrationcurve[13].
https://doi.org/10.1371/journal.pone.0193166.g002
thattheHa’apaidateswereskewedinsampleselectionfordocumentationoftheLapitato
PolynesianPlainwaretransition.SkepticismalsowasrootedbyexistingthoughtthatthePoly-
nesianPlainwarephasewasoflongerdurationandpotentiallyvariedinitschronologyamong
islandgroupsacrossTongaandelsewhereinwesternPolynesia.
Methods,radiocarbonsamplesanddatesforthePolynesian
Plainwarephase
Allnecessarypermitswereobtainedforthedescribedstudy,whichcompliedwithallrelevant
regulations.PermitswereapprovedbyCabinetDecision(CD)oftheGovernmentofTonga
includingCD996July23,1990;CD868June20,1996;CD395March26,1997;CD660May5,
1999;CD1259August32001andCD527,April2,2003.Archaeologicalcollectionsrecovered
aspartoffieldworkarerepositedandaccessiblewithintheDepartmentofArchaeologyat
SimonFraserUniversity(Burley),Burnaby,BC,Canada,www.sfu.ca/archaeologyorinthe
SchoolofCulture,History&Language,AustralianNationalUniversity(Clark),Canberra,
Australia,http://chl.anu.edu.au/.
ToaddresstheextentofPolynesianPlainwarechronologyforTongamorethoroughly,we
add25additionalradiocarbonmeasurementstothesampleof19datespreviouslyanalyzed.
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LossofceramicsinTonga
Detailedinformationforthe44samplesisprovidedinS1File.Sixteenofthesesampleshereto-
forehaveyettobereportedupon.Alldatesaretakenfromwoodcharcoalwith17fromshort-
livedmaterials,predominantlycoconutendocarp.Intentionallyweexcludedatesonmarine
shellandboneforreasonsprovidedinBurleyetal.[5].Sampledistributionnowincludes14
datesfromfivesitesonTongatapu,24datesfromsixsitesintheHa’apaigroupandsixdates
fromtwositesinVava’u.Theskewinspatialdistributionrelatestonumberofinvestigated
sitesandavailabilityofcharcoalsamplesfordating.IntheHa’apaiandTongatapusiteschar-
coalsamplesareabundant;inVava’utheyaremorelimitedintheiroccurrence.Notablyall
buttwoofthesampleswererecoveredandsubmittedbyBurleyorClarkfordirectmeasure-
mentof14Cwithacceleratormassspectrometry.
The13archaeologicalsitesfromwhichthesamplesderiveareconsistentinbeingcoastal
settlementsfirstoccupiedduringorneartheendoftheLapitaphasebutwithcontinuity
throughPolynesianPlainwareintolateraceramicperiods;severalhavecontinuityintocon-
temporaryvillages.ExceptionsareHolopekaonLifukaIslandinHa’apaiandFakala’aand
MoisaontheFangakakauLagoonshoreofTongatapu.Inthesesitesoccupationdidnotbegin
untilthePolynesianPlainwarephase,butwithsettlementcontinuinguptothepresent.All
siteshavedefinedstratigraphiccontextswithinwhichattemptsaremadetoinferlater,middle
orearlierPolynesianPlainwarecontextsformanyofthesamples.InmostcasesthePolynesian
Plainwarestratumishomogenousinitscompositionhavingamatrixoforganicallyrichsedi-
ment,abundantceramicsandotherculturalmaterials,faunalremainsincludingshellfishand
firebrokenrockfromhearthorprocessingfeatures.TodifferentiateearlierfromlaterPolyne-
sianPlainwaresamples,therefore,reliesonverticalprovenienceeithermaintainedbydepthof
sampleorthespitthesamplewasrecoveredfrom.Thisisnotanidealcontextforrelativechro-
nologyasoccupationdepositsforthePolynesianPlainwarestratummayvaryindepthand/or
thicknessacrossasitewhilemiddenaccumulationisirregularinitsdeposition.Inthreecases,
weareabletodatemultiplesamplesatvaryingdepths/spitsfromwithinsingle1x1mexcava-
tionunits.Theseunitsprovideatentativemeasureofverticalcontrolagainstwhichdatescan
beassessed.Thenatureandabundanceoftheundecoratedceramicassemblageassociated
withradiocarbonsamplesalsohaspotentialforinformationonrelativeage[14].
Table1providesmeasurementsforthe44sampleswithcalibratedrangesplottedonFig3.
ExpandeddetailforindividualdatesisincorporatedasS1File.Allsamples,includingthose
previouslyreported,havebeencalibratedorrecalibratedemployingtheSH13southernhemi-
sphericcalibrationcurvewith68.2%and95.4%probabilityranges[13].Thecumulativeresult
canonlybedescribedasconsistent,homogeneous,informativeandconvincing.Theearliest
uncalibratedradiocarbondate,2645±35BP(CAMS119695),isfromthesiteofFalevaion
KapaIslandintheVava’uislandgroup.Themostrecentare2330±60BP(Beta14171)from
TongolelekaontheislandofLifukaintheHa’apaigroupand2380±51BP(NZ636)from
TufumahinaontheislandofTongatapu.ThestratigraphiccontextfortheFalevaisample
markstheLapitatoPolynesianPlainwaretransitionandthecalibratedage(2791–2502calBP,
95.4%)isappropriatetotheeventbeingdated[5].TheTongolelekaandTufumahinadatesare
theonlytwosampleswithinthedatasetwithoutAMSmeasurement,andtheyaretheonlytwo
samplesnotrecoveredandselectedfordatingbyeitherBurleyorClark.Thattheyarethemost
recent14Cmeasurementsmaybecoincidence,butacircumstancepotentiallyidentifyingthem
asoutliers.Thecalibratedrangesforthesedatesat95.4%,however,overlapwithothersamples
inthedatasetleavingustoincludethemhere.
Inthesouthernhemispherecalibrationcurve,theHallstattPlateaucanbeplottedbetween
2430and2585BP(Fig2)butwithvariableimpactsonearlierandlaterdatesbasedonstandard
errorandGaussiandistribution(Fig3).Significantly,allbutfivedateswithinthesamplefall
directlywithinthe2430–2585BPintervalcreatingsubstantiveproblemsforprecisionin
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LossofceramicsinTonga
Table1. RadiocarbondatesaforPolynesianPlainwareoccupationstrata,KingdomofTongaorderedbyoldesttoyoungest.
Group/Islandb Site SampleID 14Cdate CalBP95.4%c Material Reference
Vava’u/Kapa Falevai CAMS119695 2645±35 2791–2502 charcoal [14]
Ha’apai/Lifuka Tongoleleka CAMS34559 2600±60 2780–2380 charcoal [5]
Ha’apai/Lifuka Holopeka CAMS12919 2590±60 2768–2380 charcoal [5]
Tongatapu Ha’ateiho UOC-3859 2583±22 2749–2494 endocarp new
Ha’apai/’Uiha Vaipuna CAMS41523 2580±50 2758–2434 charcoal [5]
Vava’u/Kapa Otea UOC-3865 2572±26 2748–2490 charcoal new
Tongatapu Talasiu Wk-23002 2562±30 2746–2486 charcoal [15]
Vava’u/Kapa Falevai UOC-3871 2561±25 2744–2489 charcoal new
Ha’apai/’Uiha Vaipuna CAMS41525 2560±80 2752–2364 charcoal [5]
Ha’apai/Foa Faleloa CAMS7146 2560±60 2750–2379 charcoal [5]
Ha’apai/Lifuka Tongoleleka CAMS34560 2560±50 2750–2380 charcoal [5]
Ha’apai/Ha’ano Pukotala CAMS41515 2560±50 2750–2380 charcoal [5]
Tongatapu Talasiu Wk-33572 2553±25 2741–2487 endocarp [15]
Ha’apai/Foa Faleloa CAMS41529 2550±50 2746–2380 endocarp [5],[16]
Ha’apai/Lifuka Tongoleleka UOC-3873 2550±23 2740–2486 charcoal new
Tongatapu Ha’ateiho UOC-3860 2542±25 2738–2462 charcoal new
Ha’apai/Lifuka Holopeka CAMS41527 2540±50 2742–2379 endocarp [5],[16]
Ha’apai/Ha’ano Pukotala CAMS41517 2540±50 2742–2379 charcoal [5]
Ha’apai/Lifuka Tongoleleka UOC-3872 2540±24 2737–2462 charcoal new
Vava’u/Kapa Otea UOC-3863 2529±29 2734–2380 endocarp new
Ha’apai/Lifuka Holopeka CAMS41528 2510±50 2717–2364 charcoal [5]
Ha’apai/Ha’afeva MeleHavea CAMS41521 2510±50 2717–2364 charcoal [5]
Tongatapu Talasiu Wk-28235 2510±30 2715–2379 endocarp [15]
Ha’apai/Ha’afeva MeleHavea UOC-3868 2505±22 2710–2378 endocarp new
Tongatapu Talasiu Wk-33574 2504±25 2710–2376 endocarp [15]
Vava’u/Kapa Falevai CAMS119694 2500±35 2708–2363 charcoal [16]
Tongatapu Ha’ateiho UOC-3861 2499±22 2705–2363 charcoal new
Tongatapu Ha’ateiho UOC-3862 2493±25 2704–2360 charcoal new
Ha’apai/Ha’afeva MeleHavea UOC-3866 2493±22 2704–2360 charcoal new
Ha’apai/Ha’afeva MeleHavea UOC-3869 2491±22 2702–2360 endocarp new
Ha’apai/Lifuka Tongoleleka CAMS41512 2490±51 2710–2357 endocarp [5],[16]
Ha’apai/Ha’afeva MeleHavea CAMS41519 2490±50 2710–2357 endocarp [5],[16]
Vava’u/Kapa Falevai UOC-3870 2483±22 2700–2356 charcoal new
Ha’apai/Ha’afeva MeleHavea UOC-3867 2478±22 2700–2356 unidnut new
Tongatapu Talasiu Wk-28234 2473±31 2701–2353 endocarp [15]
Tongatapu Moisa S-ANU-54629 2461±32 2700–2350 endocarp new
Ha’apai/Lifuka Tongoleleka UOC-3874 2460±22 2696–2350 charcoal new
Tongatapu Talasiu Wk-22876 2452±30 2698–2346 charcoal [15]
Ha’apai/Lifuka Tongoleleka CAMS34558 2450±40 2700–2346 charcoal [5]
Tongatapu Talasiu Wk-33573 2448±25 2695–2346 endocarp [15]
Tongatapu Fakala’a S-ANU-54628 2439±38 2700–2431 endocarp new
Ha’apai/Lifuka Tongoleleka CAMS41513 2430±50 2702–2330 endocarp [5],[16]
Tongatapu Tufumahina NZ-636 2380±51 2695–2163 charcoal [17]
Ha’apai/Lifuka Tongoleleka Beta14171 2330±60 2487–2116 charcoal [11]
aDetaileddatafordatesaregiveninS1File.
bIslandgroupsonwhichsitesarelocatedareidentifiedinFig1.
cDatesarecalibratedwithOxcalusingthesouthernhemisphere2013(SHcal13)calibrationcurve[14].
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LossofceramicsinTonga
Fig3.Plotofcalibratedradiocarbonages(95.4%)forPolynesianPlainwaresitesinTonga.PlotwasdoneonOxcalwith
calibrationsdoneusingthesouthernhemisphere2013(SHcal13)calibrationcurve[14].
https://doi.org/10.1371/journal.pone.0193166.g003
calibrationorinterpretationofregionalvariationinchronology.Thatbeingsaid,weareable
toconstraintheearliestboundaryforthePolynesianPlainwarephasetoca2700calBPbased
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LossofceramicsinTonga
onenddatesfortheLapitaphaseinpreviousBayesiananalysis[5].Wealsofeelsecureiniden-
tifyingitsmostrecentboundaryasnomorethan2350calBP,theapproximatecalibratedend
datefortheHallstattPlateau[12].Thedurationofceramicproductionafterthedisappearance
ofLapitapotteryacrossalloftheislandgroupsinTonga,thus,hasanestimatedchronological
extentof350yearsorpotentiallyless.
TrepidationrelatedtoageskewinginsampleselectionforHa’apaidatesandpossibleprob-
lemsrelatedtochronologicalassociationsforstratigraphiccontextarenotedearlier.Thethree
excavated1x1munitswithmultipleradiocarbondatesatincreasingdepthsacrossthePoly-
nesianPlainwarestratumwereintendedtoprovideperspectiveinthisregard(Table2).The
samplesderivefromasingleunitatTalasiuexcavatedbyClark[15]andtwounitsfromTon-
golelekaonLifukaIsland,Ha’apaiexcavatedbyBurley[16].Ineachcase,theradiocarbonsam-
pleswereselectedfortheirvarieddepthswithinthePolynesianPlainwarephaseoccupation
zoneand,basedondepth,aregivencontextualassociationsoflowertoupperatTalasiuor
Lapita/PlainwaretransitiontoLatePlainwareatTongoleleka.AsillustratedinTable2,inno
caseisthereaprogressivesequenceofdates.Thisisnotsurprisingnorcontradictory.Alldates
areinfluencedbytheHallstattPlateauwhichiscausedbyatmosphericvariationsin14Ccon-
tentandchangesinthecarboncycle[18].Theconsequenceisaflatteninginthecurvebut
withundulatingwigglesofpeaksandtroughs(Fig2).Adatecouldfallinthelowertroughofa
wigglewherethereisadecreaseinatmospheric14Cwhileanothermayfallonapeakwhereit
isincreased.Theconsequence,then,canbetheappearanceofareversed14Cclockasisthe
caseatTalasiuandTongolelekaUnit11.
TheimplicationoftheHallstattplateauforradiocarboncalibrationissignificantinthat
chronologicalprecisionbecomesallbutimpossible.ThisisparticularlytrueinEuropewhere
almosttheentiretyofIronAgesettlementfallswithinitstemporalspan[19].Apartialsolution
hasbeenwiggle-matching,atechniquethatmatchestheshapeofaseriesofsequentiallycali-
bratedradiocarbonagestotheshapeoftheradiocarboncalibrationcurve[20].Thisrequires
knownageseparationsbetweendatestoaccuratelyfitthecurvSe,limitingmostapplicationsto
woodsampleswhereatreeringsequenceispresent.Alternatively,wheredepthmeasurements
forsamplesprovidechronologicalorder,matrixaccumulationratesmustbeconstantand
known[21].NeitheroftheseappliestocurrentconsiderationsofthePolynesianPlainware
phasedateswherevirtuallyallsamplesaresmallflecksofcharcoalorwhereaccumulation
ratesinmiddencontextsareassumederratic.ThepotentialforrefinementofaPolynesian
Table2. SequentialradiocarbondatesforPolynesianPlainwareoccupationsfromthreeexcavationunitsintheKingdomofTonga.
Site/Unit Spit/Depth Context 14CDate Cal95.4% LabNumber
TalasiuPit2 Spit4 upper 2553±25BP 2741–2487BP Wk-33572
TalasiuPit2 Spit11 middle 2448±25BP 2695–2346BP Wk-33573
TalasiuPit2 Spit18 lower 2504±25BP 2710–2376BP Wk-33574
TongolelekaUnit11 Level4(36dbs)a midtolatePPWb 2540±24BP 2737–2462BP UOC-3872
TongolelekaUnit11 Level4(38dbs) midtolatePPW 2490±51BP 2710–2357BP CAMS41512
TongolelekaUnit11 Level7(66dbs) earlytomidPPW 2430±50BP 2702–2330BP CAMS41513
TongolelekaUnit11 Level9(89dbs) LAc/PWTrans 2460±22BP 2696–2350BP UOC-3874
TongolelekaUnit4 Level5(50dbs) midPPW 2450±40BP 2700–2346BP CAMS34558
TongolelekaUnit4 Level8(75dbs) earlyPPW 2600±60BP 2780–2380BP CAMS34559
TongolelekaUnit4 Level10(103dbs) LA/PPWTrans 2560±50BP 2750–2380BP CAMS34560
adbs=depthbelowsurface
bPPW=PolynesianPlainware
cLA=Lapita
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LossofceramicsinTonga
Plainwarechronologyexistsnevertheless.ThiswillrequirefutureacquisitionandU/Thdating
ofcoralartifactsfromappropriatecontexts,ashasbeenemployedinearlierBayesiananalysis
ofLapitaphasesettlementexpansionacrossTonga[5].U/Thmeasurementoncoralisnot
affectedbyfluctuationinatmosphericcarbonwhilecalibrationisindependentofradiocarbon
calibrationcurves.U/Thmeasurementalsoprovides2σcalibrateddateswithexceptionalpre-
cisionintherangeof±6to10yearsforthetemporalperiodunderconsideration.
Discussion
ThePolynesianPlainwarephaseacrosswesternPolynesiaisdefinedasapivotaltransition
markingtheonsetofancestralPolynesia.The44radiocarbondatesforthisphaseinTongaas
presentedherearecategoricalandinformative.Comingfrom13sitesacrossmultipleislands
fromsouthtonorth,thesedelineateamaximumtemporalintervalof2700–2350calBPforits
duration.Themostrecentboundaryforthisintervalissubstantiallyearlierthanpreviously
inferredforcessationofceramicproductioninTonga;indeed,itexceedsourpriorestimates
byatleast800years[11],[22].Compressingexistinginterpretationsofdevelopmentand
changeduringthePolynesianPlainwarephaseintoa350-yeartemporaldurationhasseveral
implicationsforanunderstandingofancestralPolynesiansocietyasithasbeenpreviously
defined,theTonganpast,aswellasregionalrelationshipsinwesternPolynesia.Eachofthese
issuesistakenupasfinaldiscussion.
AncestralPolynesiansociety
ThesettlementofPolynesiarepresentsafinalphaseinarapiddispersalofpeoplesacross
RemoteOceaniadefinedbyLapitaceramicsashasbeennoted.OncewesternPolynesiawas
colonized,furthermovementeastwardintotheremainderofPolynesiadidnotoccurforas
muchas1800years[23].Referredtoasthe“longpause”,thiswasaperiodoftimeinwhich
PolynesiansliterallybecamePolynesian,developingaPolynesianculturaltemplateaswellasa
discretelinguisticsub-stage,proto-Polynesian.Itisadevelopmentalphasetypicallyreferredto
asancestralPolynesiawithwesternPolynesiabeingtheancestralPolynesianhomeland[2].
TheappearanceofPolynesianPlainwareceramicsasadistinctandintegratedassemblageis
takenasamarkerforitsearliestbeginnings,onedistinguishingitfromLapitainwesternPoly-
nesiaandelsewhereinOceania.
KirchandGreen[2]arguethatPolynesianculturesformaphyleticunittowhichaphyloge-
neticapproachmaybeapplied.AllPolynesians,intheirview,shareacommonhistoryanda
commonancestor.Throughdetailedanalysesofthedata,notonlycanthathistorybemapped
asaseriesofdivergingrelationships,buttheancestralculturaltemplatecanbeappropriately
definedthroughintegrationofcomparativehistoricallinguistics,comparativeethnography,
archaeologicaldata,andtoalesserextentbiologicalanthropology.Groundedinproto-Polyne-
sianlexicalreconstruction,thisapproachhasprovidedapowerfultoolforarchaeologicalinfer-
enceofthePolynesianPlainwarephase.Numerousaspectsofmaterialculture,social
organization,ritualactivitiesandthelikearepoorlyifeverpreservedinarchaeologicalcontext
butquiteaccessiblethroughaproto-Polynesianlexiconorcross-referencedincomparative
ethnographythroughhomologousrelationship.InthisKirchandGreen[2]gosofarastopro-
poseproto-PolynesiantermspotentiallyapplicabletoPolynesianPlainwareceramictypes.
Proto-Polynesianisdefinedasaninnovation-richlanguagestagerequiringaconsiderable
periodoftimeinitselaboration[2].Pawley[24],forexample,estimatesadevelopmental
periodof1000yearsduringwhichwesternPolynesianpeoplesspokethesamelanguageand
whereasharedcollectiveoflinguisticinnovationsstructuredandcametodefineproto-Poly-
nesian.ToequateitwiththePolynesianPlainwarephasesimilarlyimpliesalengthyperiodof
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LossofceramicsinTonga
commondevelopmentacrosswesternPolynesiaasawhole.Thatwedefinetheendofceramic
productioninTongaat2350calBPcomplicatesthismatter.Asahomogenousentityfor
ancestralPolynesia,thisphasenowhasamaximumextentofnomorethan350yearsand
quitepossiblyless.ThedevelopmentofregionalvariationsinPolynesianPlainwareceramic
formssimilarlyhasbeencorrelatedwithemergentlinguisticandsocietaldiversityinthediffer-
entislandgroupsofwesternPolynesia[2].Aglotto-chronologicalestimateforthebreakupof
proto-Polynesian[24],aneventpresumablytiedtotypologicaldivergenceinthearchaeolog-
icalrecord,alsoisdiscordantinthatitnowpost-datesPolynesianPlainwareinTongaby300
years.
ThecorrelationoflinguisticandarchaeologicalevidenceinPolynesiaischallengingatbest
sinceeachformanindependentdataset.Materialcultureandlanguagecanbesubjectto
changefordifferentreasons,andchangeineachcanoccuratdifferentrates.Adirectcorrela-
tionbetweenthePolynesianPlainwarephaseasdefinedbyceramicsandadevelopmental
sequenceforproto-Polynesianlanguagejustifiablycanbequeried.Thiscircumstancedoesnot
contestthevalidityofcomparativehistoricallinguistics.Forthelinguist,theabsenceofarchae-
ologicalcorrelationmakesitmoredifficulttopositionlinguisticeventswithinrealtimechro-
nologythatarchaeologistsareabletogenerate.Forthearchaeologist,itdampensourabilities
tofillindetailsofthepastthatarenotwellpreservedinthearchaeologicalrecord.Itdoesnot,
however,obviateinsightsgainedfromlexicalreconstructionwherearchaeologicaldatamaybe
abletotestthoseinferences.
ImplicationsforTongandemography
BeginningwithfirstlandfallonTongatapu,theLapitasettlementofTongawasexpansive
throughoutthearchipelagoyetephemeralinpopulationsizeandthenumberofsettlements
involvedinthisundertaking[25].AllLapitasiteswerepositionedincoastalsettingsforthe
exploitationofforeshoreandmarineresourcesbutwithsubsistenceeconomyadditionally
incorporatinglowlevelhorticulturalproduction[4],[11].Thefulldurationofthisphaseon
Tongatapuisonly150orsoyearsandconsiderablylesselsewhere[5].Atbest,Lapitasettle-
mentprovidedanascentfootholdforsubsequenteventsinthePolynesianPlainwarephase.
PolynesianPlainwarephasesitesinTongaareubiquitous,sometimessubstantial,andthey
occuronvirtuallyeveryinhabitableislandacrossthearchipelago,includingbothcorallime-
stoneandvolcanicformations[26].Theabundanceanddistributionofthesesitessuggesta
periodwithmajordemographicgrowthand,bytheendofthephase,anexpansiveifnotfull
useoftheTonganlandscape[11].OnTongatapu,Plainwaresettlementwasnotrestrictedto
theleewardlagoonsystemaswasthecasewithmostsitesoftheLapitaphase.Rathersitesare
foundinallcoastalareas,onsmalloffshoreislandsandtheyaredispersedacrosstheisland’s
interior[25].Groube[8],infact,commentsthatplainwarepotteryconcentrationsaresodense
inplaces,thatTongansconsideredceramicsherdstobe“partofthesoilitself”.Ontheisland
ofLifuka,inthecentralHa’apaigroup,aridgeofoccupationwithPlainwareceramicsispres-
entontheleewardcoaststretchingoveracontinuousdistanceof5km,butwithseveralinten-
siveoccupationnodes[25].AndevenonthefarnorthernoutlierofNiuatoputapu,Kirch
reportsa50mwidezoneoflargelyPlainwarearchaeologicaldepositsthatencircletheisland’s
volcaniccore[27].
ThisdistributionanddensityofPlainwaresitessuggestsaperiodofpopulationgrowthfar
beyondwhatmightbeexpectedforthe350yearsofthePolynesianPlainwarephase.Ifwe
employHassan’s[28]maximumgrowthrateof0.0052forprehistoricpopulations,assumea
Lapitafoundercolonyof100individualswithexponentialgrowth,andcalculateapopulation
at2350calBPforthePolynesianPlainwarephase,theprojectednumberofindividualsisno
PLOSONE|https://doi.org/10.1371/journal.pone.0193166 February23,2018 10/15