THE
MORRO
BAY
FAUNA:
EVIDENCE
FOR
A
MEDIEVAL
DROUGHTS
REFUGIUM
ON
THE
CENTRAL
CALIFORNIA
COAST
TerryL.Jones,DeborahA.Jones,KaceyHadick,KennethW.Gobalet,JudithF.Porcasi,and
WilliamR.Hildebrandt
Arobustcollectionofmammal,bird,fish,andshellfishremainsfroman8,000-yearresidentialsequenceatMorroBay,asmall,
isolatedestuaryonthecentralCaliforniacoast,showsastrongfocusonmarinespeciesduringtheMiddle-LateTransition
culturalphase(950–700calB.P.),whichlargelycoincideswiththeMedievalClimaticAnomaly(MCA).Previousstudieshave
providedmodestevidenceforincreasedfishingandrabbithuntingduringtheMCAinadjacentregions,buttheMorroBay
findingssuggestadistinctivemarine-focusedsubsistencerefugiumduringtheperiodofdrought.Specifically,thesequence
showsstrikingall-timepeaksinmarineandestuarinebirds,fishNISP/m3,andfish/deer+rabbitsduringtheMCA.Heavy
exploitationoffish,aquaticbirds,rabbits,andshellfishsuggeststhatthebowandarrow,whichseemstohavearrivedinthe
areaatthistime,hadlittleimpactonlocalsubsistencestrategies.
Lasecuenciaresidencialdeunos8,000añosdeduraciónprocedentedeMorroBay(unpequeñoestuarioaisladoenlacosta
centraldeCalifornia,EstadosUnidos)estácompuestaporungranconjuntofaunísticoqueincluyerestosdemamíferos,
aves,pecesymariscos.Dichoconjuntofaunísticoindicaunafuertedependenciadelasespeciesmarinasdurantelafase
culturaldelaTransiciónMedia-Tardía(950–700cala.P.),lacualcoincideplenamenteconlaanomalíaclimáticamedieval
(MCA).Algunosestudiosprevioshanmostradomodestasevidenciassobreelincrementodelapescaylacazadelepóridos
durantelaMCAenlasregionesadyacentes.Sinembargo,enMorroBayloshallazgossugierenlapresenciadeunrefugio
basadoenlosrecursosmarinosaniveldesubsistenciaduranteelperiododesequía.Específicamente,lasecuenciamuestra
unospicosnuncaantesvistosenelnúmerodeespecímenesidentificados(NISP)pormetrocúbicoderestosdeavesmarinas
ydeestuario,mariscosypecesenproporciónalacantidaddecérvidosylepóridosduranteelMCA.Laintensaexplotación
delapesca,lasavesacuáticas,loslepóridosylosmariscossugierenquelallegadadelarcoylaflecha,coincidenteconel
mismoperiodo,tuvounimpactoreducidoenlasestrategiasdesubsistencialocales.
O
ne of the most long-standing issuesin the study of western North
Ameri-canhunter-gathererprehistoryhasbeen
the relative influence of paleoclimatic
varia-tion on cultural change. Since at least the
1940s,archaeologistshavebeeninterestedinthe effects of prolonged periods of aridity on for-agingpopulations.Initiallyfocusedonthe
mid-Holocene warm period (known alternately as
theAltithermal,Hypsithermal,orXerothermic;
Antevs 1948, 1955;BaumhoffandHeizer 1965; Byrne 1979;CurreyandJames 1982;Deanetal.
1985;deMenocal 2001;Jennings 1964;Kennett etal. 2007;Moratto1984:544–547;Morattoetal.
1978),debatehassinceshiftedtotheMedieval
ClimaticAnomaly(MCA)ofthelateHolocene
(Arnold 1992; Basgall 1999; Bettinger 1999;
Boxt et al. 1999; Collins 2010; Cook et al.
TerryL.Jones DepartmentofSocialSciences,CaliforniaPolytechnicStateUniversity,SanLuisObispo,CA93407,
USA(Tljones@calpoly.edu,correspondingauthor)
DeborahA.Jones FarWesternAnthropologicalResearchGroup,1725DiabloDrive,SanLuisObispo,CA93405, USA
KaceyHadickandWilliamR.Hildebrandt FarWesternAnthropologicalResearchGroup,2727DelRioPlace,SuiteA, Davis,CA95618,USA
KennethW.Gobalet DepartmentofBiology,Emeritus,CaliforniaStateUniversity,Bakersfield,CA93311Current Address:625WisconsinSt.,SanFrancisco,CA94107,USA
JudithF.Porcasi CotsenInstituteofArchaeology,UniversityofCalifornia,LosAngeles,CA90095,USA
AmericanAntiquity82(2),2017,pp.203–222
Copyright©2017bytheSocietyforAmericanArchaeology
doi:10.1017/aaq.2016.31
2004; D’Oro 2009; Fischman 1996; Gamble
2005;Herweijeretal.2006;Johnson2004;Jones etal. 1999; Jones andBrown 1999; Jonesand Schwitalla 2008,2012; Kennett 2005; Kennett
and Kennett 2000; Lambert 1994; Raab and
Larson 1997; Schwitalla 2012; Walker and
Lambert 1989).Stine(1994) definedtheMCA
as a period of prolonged and severe droughts
between ca. 1150 and 600 cal B.P. Originally
recognizedinthepaleoclimaticrecordsof both
California and Patagonia, the MCA is now
reasonably well accepted as a distinctive
cli-maticinterval,withrecentstudiesconfirmingthe occurrenceofepicdroughtsandelevatedaridity
inNorthAmericaduringmedievaltimes(Cook
etal. 2004;Grahametal. 2007, 2011;Graumlich
1993;Mannetal. 2009),aswellascorrelations
with major cultural changes (including
large-scalemigrationsandcollapse;e.g.,Bensonand Berry 2009;Bensonetal. 2007, 2009;Berryand Benson 2010;Billmanetal. 2000).
InCalifornia,theeffectsofmedievaldroughts onnativeforagingpopulationshavebeendebated intenselyformorethantwodecades(seereviews bySchwitalla 2010;SchwitallaandJones 2012). In most of thisregion, the cultural phase that
coincideswiththeMCAisknownasthe
Middle-LateTransition, dated ca. 950–700 cal B.P. In
central and southern California, most scholars
acceptthatchangesinexchange(Arnold 1992; Gilreath 1995;Gilreath andHildebrandt 1997; Jones etal. 1999;Jones andSchwitalla 2008), settlementpatterns(Arnold1992;Kennett2005),
regional abandonments, (Jones and Ferneau
2002;Gardner 2006;JonesandSchwitalla 2008; Whitley etal.2007),anddiseaseandviolence (Fischman 1996;Lambert 1994, 1997;Raaband Larson 1997;WalkerandLambert 1989; Weiss
2002)duringtheMiddle-LateTransitioncanbe attributedtodemographicstressescausedby
pro-longedandseveredroughts.However,somehave
arguedthatthedroughtswerenotsevereenough
to causemajor problems(Basgall 1999,2008;
Bettinger 1999)or thatNative mechanismsfor
water storage and resourceredistribution were
sophisticated enough to mitigate any serious,
negativeconsequences(e.g.,Gamble 2005)and that,aboveallelse,Nativepopulationssurvived
(Arnold and Walsh 2010:34). In this regard,
findings from northern California have been
muchlesscompellinginimplicatingdroughtas
aprimaryagentofculturalchange.Somestudies
of the skeletal record fromSan Francisco Bay
andtheSacramento-SanJoaquinValley(D’Oro
2009;Pilloud 2006;Schwitallaetal. 2014) have
not found the same spike in violence during
the MCA/Middle-LateTransitionthat Lambert
(1994)documentedintheSantaBarbara
Chan-nel.Analysis ofametadatasetofburials from
the San Francisco Bay area confirmed a peak
in projectile violence during the Middle-Late
Transition,butalsoshowedaconcurrentpeakin dentalcariouslesions,whichwasattributedtoa heavyrelianceonacornstorageandconsumption (SchwitallaandJones 2012).Thelatterindicates viabilityof theacorn cropduringthe droughts
in central California and some measure of a
reliable food base. Subsistence patterns based
onfaunalremainsfromSanFranciscoBayhave
alsomorecommonlybeenattributedtoeconomic
intensification (Broughton 1997, 1999) rather
thanclimaticallyinducedculturalchange.Most recently, Bettinger (2015) suggested that the
medievaldroughtsmayhaveamplifiedprocesses
thatwerefundamentallyhistoric/diffusionaryin nature,astheintroductionofthebowandarrow intoCaliforniaultimatelyfacilitatedmore inten-sive,privatizedeconomicsystems.
When Arnold (1992) first attributed settle-mentandsocialtransitionsonthesouthern Cali-forniaIslandsduringtheMiddle-LateTransition
(MLT) toclimatic changes,she suggested that
theprimaryproblemconfrontingthesemaritime
hunter-gathererswaswarmseasurface
temper-aturesthat drasticallyreduced the productivity
of the marine food base. Subsequent studies
(KennettandKennett 2000)showedthatsea sur-facetemperatureswereinfactcooland produc-tiveduringtheMCAandthatsubsistencestress wasmoreaproductofreducedprecipitationand aresource-depletedterrestrialenvironment.The
native response to the latter, which has been
further supported by subsequent paleoclimatic
studies (Barron et al.2015), was an increased focusonmarineresourcesduringthedroughtsas wellasviolentcompetitionforlimitedresources (KennettandKennett 2000).Theideaofamarine
subsistence focus during MCA subsequently
becamecommononthecentralCaliforniacoast,
increasedexploitationoffish,marinemammals,
and/orshellfishduringtheMLT(e.g., Codding
and Jones 2007; Codding et al. 2010; Jones
2003;Joslin 2010),butthecollective empirical
evidence has not necessarily been compelling.
Mikkelsen et al. (2000), for example,
hypoth-esized that Morro Bay,a small estuary on the
central coast, may have served as a refugium
during the medieval droughts, but support for
theideawasnotimmediatelyforthcoming.Here
we affirm that hypothesis with a robust body
of faunal evidence accumulated in the last 15
yearsthatclearlyshowsaheavyfocusonmarine
resourcesalongtheshoresofMorroBayduring
the MCA.Frequenciesof fishandmarine bird
remainsfromthissettingaresignificantlyhigher
during the MLT than at any other period in
the8,000-yearoccupationalsequence,whichwe
interpret as evidence for an intense focus on
marine foods in the face of reduced terrestrial productivitycausedbydrought.Whilethefocus onfishandseabirdsislogicallyconsistentwith a depletedterrestrial biome,the availability of these foods also suggests that, at least in this setting,theeffectsofdroughtmaynot necessar-ilyhavebeen catastrophic.Further, the dietary
responseevidentatMorroBayshowsnoobvious
consequencesfromintroductionofthebowand
arrow,whichdiffusedintotheareaataboutthe sametime,andhasbeenhypothesizedasatleasta contributing(Kennett 2005;KennettandKennett
2000;Kennettetal. 2013;Lambert 1994),ifnot primary, causeof culturalchanges. Thisisnot
to saythat the bow mightnot have been used
as a weapon in intergroup conflict and that it
couldhaveledtoincreasedviolence,butitdid notcontributetosubsistencechangeatthistime.
Setting
MorroBayisashallow8.1km2coastalestuary
situated on the central Californiacoast in San LuisObispoCounty(Figure1)thatwasoccupied
byspeakersofObispeñoorNorthernChumashat
thetimeofhistoriccontact(Golla2011:194).The bayoccupiesthenorthernendofasoutheastward
trending depression that encompasses the Los
Osos and San Luis valleys (Cooper 1967:74).
Sand dunes surround the bay, and onearm of
the dunesystemisasand spitthat serves asa
barrierbetweentheestuaryandtheouterEstero
Bay.Entrance tothe bayfrom theopen ocean
was significantly improved by construction of
breakwaters in the 1940s by the U.S. Army
CorpofEngineers.Priortothatconstruction,the
mouthofMorroBaywasopentosurfactionand
wasunsuitableforshipportage.
MorroBay’sMediterraneanclimateis
char-acterized by cool moist winters and warm
dry summers,with frequent fog betweenJune
andSeptember.Annualaverageprecipitationis
370 mm/yr,witharangefrom 152to610 mm
(GerdesandBrowning 1974:21).Priorto
exten-sive moderndisturbance anddevelopment, the
natural vegetationfostered bythe combination
ofmodestrainfallanddunesoilswasacoastal
sagebrushshrub (Hoover 1970; Kuchler 1977;
Ritter2006).CommonspeciesincludeCalifornia sagebrush(Artemesiacalifornica),coyotebrush (Baccharis pilularis), poison oak ( Toxicoden-drondiversilobum),andblacksage(Salvia mel-lifera).Coastliveoakforestisonlyaverysmall
component of the vegetative landscape. This
differssignificantlyfromthe opencoast tothe south(theDiabloCanyonorPechoCoast),where oakforestismuchmoreextensive(Coddingetal.
2010;Hildebrandtetal. 2010;JonesandCodding
2010;Jonesetal. 2008).
Likemost estuarieson theCaliforniacoast, MorroBayprovideshabitatforanextensivesuite
of marine and terrestrial animals. In terms of
birds,the bayisan integral part of thePacific
flywayandisvisitedbyamyriadof migratory
species, particularly in the winter. California
FishandGamehaveidentifiednofewerthan75
speciesthatvisitor resideyear-roundatMorro Bay(Edell 2006; GerdesandBrowning 1974).
The estuary attracts the snowy egret (Egretta
thula),thegreatblueheron(Ardeaherodias),and avarietyofotherwaterfowl,shorebirds,andbirds
ofprey. Onlyfourspecies ofmarine mammals
areknowninthebaytoday:Californiasealion (Zalophus californianus), harbor seals (Phoca vitulina),Stellar’ssealion(Eumetopiasjubatus), andtheseaotter(Enhydralutris),butthe
archae-ological record indicates that elephant seals
(Miroungaangustirostris)(Ricketal. 2012)and northern fur seals (Callorhinus ursinus) (Rick etal. 2009)wereoccasionallypresentnearshore
Figure1.MorroBay,California,witharchaeologicalsitesdiscussedintext.
native terrestrial mammals were documented
aroundtheshoresofMorroBayin1974(Gerdes
andBrowning 1974).Theseincludeseveralsmall burrowingspeciesthatareagentsofbioturbation
within local archaeological sites. The largest
herbivore currently present is the black-tailed deer (Odocoileus hemionus),although tule elk (Cervus elaphus nannodes) remains are repre-sentedinsmallamountsatafewarchaeological sites (e.g., Mikkelsen et al. 2000). Cottontail andbrushrabbits(Sylvilausspp.)werecommon inhabitantsofthecoastalscrub,alongwithjack rabbits (Lepuscalifornicus). Historically, local
carnivoresincluded brown bears(Ursus
horri-bilis),mountainlions(Felisconcolor),bobcats (Lynx rufus), gray foxes (Urocyon cinereoar-genteus),coyote(Canislatrans),andlong-tailed weasels(Mustelafrenata).
Withrespecttofishes,theCalifornia
Depart-ment of Fish and Game identified 66 species
(64natives) withinMorro Bayin1966,which
weresubsequentlyconfirmedbyFierstineetal.
(1973).Thesesurveysshowedthatthreespecies
accountedformorethan50percentof thefish
inthebaybynumbercaught:northernanchovy
Table1.MorroBayStudySites.
TotalExcavation TemporalComponents
Trinomial Volume(m3) (Periods) Reference
CA-SLO-14 21.49 Middle FarWesternAnthropologicalResearchGroup(2016)
CA-SLO-23 92.39 Early,Late FarWesternAnthropologicalResearchGroup(2016)
CA-SLO-165 72.90 Millingstone/LowerArchaic, Mikkelsenetal.(2000) Early,Middle
CA-SLO-215 5.00 Millingstone/LowerArchaic Jonesetal.(2004)
CA-SLO-457 27.70 Middle-LateTransition FarWesternAnthropologicalResearchGroup(2016) CA-SLO-458 19.74 Early,Middle-LateTransition FarWesternAnthropologicalResearchGroup(2016)
CA-SLO-626 24.54 Late FarWesternAnthropologicalResearchGroup(2016)
CA-SLO-812 11.28 Millingstone/LowerArchaic, FarWesternAnthropologicalResearchGroup(2016) Early,Middle
CA-SLO-977 1.00 Early Dallas(1992)
GobaletandJones(1995)
Total 276.04
aggregata), and black perch (Embiotoca jack-soni).Atleast11species,includingblackperch,
shiner perch, lingcod (Ophiodon elongatus),
Pacificstaghorn sculpin(Leptocottusarmatus), and starry flounder (Platichthys stellatus), are year-roundresidentsoftheestuary.Asmanyas
29otherspeciesareseasonalmigrants(Gerdes
andBrowning 1974).
ThehistoryofresearchatMorroBayreflects the relative isolation of the estuaryaway from
the major centers of archaeological inquiry in
California. While the San Francisco Bay shell
middensbegantobeseriouslyinvestigatedover 100 years ago(Nelson 1909), the first sitesat MorroBaywerenotrecordeduntilthelate1940s,
the first excavation was not completed until
1961(Clemmer 1962),andthefirstradiocarbon
dates were not obtained until the late 1970s.
Research on the prehistory of Morro Bay has
takenplacewhollywithintheCulturalResource
Management(CRM)era.Landssurroundingthe
bay are held in private (small residential lots)
andbyCaliforniaStateParks,andmostof the
earlyCRMworkonthesepropertieswaslimited
torelativelysmall-scalesurvey andtesting.As of 2015,at least 50 siteshadbeen tested,and radiocarbondatesareavailablefrom28ofthese,
butmost of theseinvestigations,while
accom-plishing the conservation objectives for which
theywereintended,didnotproducesubstantive
samples of well-dated faunal remains and/or
artifacts. In the last 15 years, there have been severalsubstantialinvestigationsontheshoreof
theestuary,alongwithseriousattemptsat syn-thesis(e.g.,Bertrando2000,2004a, 2004b;Jones etal. 2004;Mikkelsenetal. 2000)highlightedby
therecentLosOsosWastewaterProject,which
yielded substantial artifact andfaunal samples fromeightsitesinthesouthernportionofthebay
(FarWestern AnthropologicalResearch Group
2016). The Los Osos findings, in conjunction
with other local research, have established an
8,000-yearoccupational historyfor MorroBay
markedbyasubstantialquantityoffaunaldata.
Herewesummarizethefish,mammal,bird,and
shellfish remains from nine sites investigated
over the last two decades (Table1, Figure1), representingallperiodsinthissequence.
Methods
FieldRecovery
Theinvestigatedsiteswereestuarineshell
mid-densmarkedbycombinationsofmammal,bird,
and fish bone, shellfish remains, fire-affected
rock, flaked stone tools and debitage, ground
stone,boneandshelltools,andoccasional fea-turesincludinghumanburials.Allinvestigations
atthesedepositswerecompletedbetween1990
and 2013 (Table1). Two sites, CA-SLO-215
andCA-SLO-977, weresubjected torelatively
modesttesting(1.0–5.0m3)toevaluatethetype
and distribution of materials present (Dallas
1992; Joneset al.2004).Largersamples were
2000),CA-SLO-14,CA-SLO-23,CA-SLO-457,
CA-SLO-458,CA-SLO-626,andCA-SLO-812.
Total recoveryvolumefortheseninesiteswas
276.04m3 (Table1).Excavatorsobtainedmost
samplesfromthesedepositsviadryfield
screen-ing (3 mm mesh) from 1 × 2 m and/or 1 ×
1 m units test units or trenches. Excavators
collected vertebrate remains in unit-level lots fromallmanuallyexcavatedunitsexceptinrapid recoveryunitsemployedonalimitedbasisatone
site(CA-SLO-23in2013).
The abundanceof fishand shell remainsin
the deposits required a subsampling strategy.
Control units and column samples provided
the assemblage of fish remains at most sites,
while component-associated subsamples
pro-videdsamples atsitesthat producedextremely
largenumbersoffishbones.Thelatterincluded
a representative sample of control units
(pro-cesseddrywith1/8-inchmesh)andone-column
sample level (representing 20 ×20 ×10 cm)
of recovery volume processed in the
labora-torywithwaterthrough nested1/8- and1/16-inch
mesh.1
Shellfishremainswere,byfar,themost abun-dant,visibleculturalconstituentsinthedeposits.
Column samples provided a primary way of
recoveringacontrolledrepresentativesampleof shellremainsfrombothfeatureandnon-feature
site deposits. The shell column samples were
laboratory-processedwithwaterthroughnested
1/4-,1/8-,and1/16-inchmesh,dried,cataloguedby
screensizeandunitprovenience,andsortedfor cultural andnoncultural constituents. Analysts examinedtheshellremainsfrom1/4- and1/8-inch
meshsamples.
Analysis
UsingreferencecollectionsfromtheLos
Ange-lesCountyMuseumofNaturalHistoryandthe
ZooarchaeologyLaboratoryattheCotsen
Insti-tuteofArchaeologyatUniversityofCalifornia,
LosAngeles,Porcasiidentifiedbirdandmammal
remainsfromallbutoneofthesites.2 Jameson andPeeters(1988)andPeterson(1990)provided
the nomenclature and taxonomyfor mammals
and birds, respectively. Porcasi identified all
specimenstothemostdiscretetaxonomiclevel
possible based on diagnostic features. In the
absenceofsuchfeatures,sheassignedbonesto
classes(i.e.,Mammalia,Aves,etc.)and(forbirds andmammals)tosizecategories(small,medium, orlarge).Inaddition,sherecordedtothedegree possibletheelement,partofelement,side,age,
number, weight, and evidence of modification
(i.e.,burned,gnawed,cut,orworked).The
Mar-galefIndexprovided ameasureof assemblage
diversitytoevaluatedietbreadthandthe
Berger-Parker index (in reciprocal form) to evaluate
evenness or relative specialization (Magurran
1988).
Gobaletidentifiedtheelementandtaxonomic
categoryof eachfishspecimenusingreference
materials.3 Findings were summarized by the
number of identified specimens (NISP). The
nomenclature and current taxonomyfor fishes
follows Pageet al. (2013). Forthis paper, we
define “identified” as specimens assigned to
at least a family. Weexcluded specimens that
wecouldclassifyonlyasElasmobrachiomorphi
(sharks, skates, rays) or Actinoptergii4
(ray-finned fishes, 16,653 elements). Jones,
Gob-alet, and Codding (2016) and Jones, Gobalet,
Mikkelsenetal.(2016)discusssomeaspectsof
thefishassemblages.
D. Jones and Hadick identified the
shell-fish using reference collections at California
PolytechnicStateUniversity,SanLuisObispo,
and Far Western Anthropological Research
Group, recording the weight of shell per
species.
Basedonthesemethodologicalprotocols,the
sample available from Morro Bay consists of
2,247 bird and mammal bones from an
ana-lytical volume of 141.60 m3, and 19,235 fish
bonesidentifiedtoameaningfultaxon(generally
familyor better) froman analyticalvolumeof
127.1 m3. Shellfish remains represent a total
recoveryvolumeof1.088m3.
ChronologyandDelineationofTemporal Components
Radiocarbondates(n=80)andtemporally diag-nosticshellbeadsandprojectilepointsprovided verticalandhorizontalidentificationof compo-nents(Table2).Seventy-eightofthedateswere
fromsingle-shellsamples,whiletheremaining
twowerefromcharredplantremains.Alldates
Table2.SummaryofMorroBayTemporalComponents.
N Analytical Analytical Analytical
N Temporally AgeSpan Excavation VolumeBird VolumeFishVolumeShell Trinomial Temporal RadiocarbonMeaningfulOne-Sigma Volume andMammal Remains Remains
CA-SLO- Perioda Dates Beads (calB.P.) (m3) Remains(m3) (m3) (m3)
23 Late 4 73 700–250 17.90 17.90 10.50 0.025
626 Late 3 34 700–450 24.50 21.40 11.70 0.032
Subtotal 7 107 700–250 42.40 39.30 22.20 0.057
457 Middle-Late 4 65 900–700 27.10 3.21 5.20 0.052
Transition
458∗ Middle-Late 1 5 1050–450 1.87 1.60 0.07∗∗ 0.070
Transition
Subtotal 5 61 1050–450 28.90 4.81 5.20 0.122
14 Middle 4 8 2050–1850 21.49 21.49 18.40 0.056
165 Middle 6 1 2400–900 1.20 1.20 1.20 0.020
812 Middle 2 6 2300–1800 3.30 3.20 2.90 0.060
Subtotal 12 15 2400–900 25.99 25.89 22.50 0.136
23 Early 8 10 4800–3350 73.21 9.00 14.60 0.077
165 Early 27 4 5700–3400 37.20 37.20 37.20 0.148
458 Early 2 0 5000–4750 17.58 9.30 9.30 0.024
812 Early 1 2 4200–4000 2.50 2.40 2.40 0.060
977 Early 3 0 3900–2800 1.00 1.00 1.00 –
Subtotal 41 16 5700–2800 131.47 58.90 64.50 0.309
165 Millingstone/ 3 2 8200–7200 3.50 3.50 3.50 0.024
LowerArchaic
215 Millingstone/ 10 0 7800–6880 5.00 5.00 4.40 0.310
LowerArchaic
812 Millingstone/ 2 2 8000–7400 4.90 4.80 4.80 0.130
LowerArchaic
Subtotal 15 4 8200–6880 13.40 12.70 12.70 0.464
Grandtotal 80 203 242.25 141.60 127.1 1.088
aLate=700–180calB.P.;Middle-LateTransition=950–700calB.P.;Middle=2600–950calB.P.;Early=5500–2600
calB.P.;Millingstone/LowerArchaic=10,000–5500calB.P. ∗Componentbasedmoreonbeadsthanradiocarbon. ∗∗Wet-screenedrecovery.
2016); a Delta R marine correction value of
290 ± 35 years (Ingram and Southon 1996)
was applied to the shell dates. Components
excluded portions of the excavation volume
that were disturbedor that exhibited excessive
temporal mixing so that the volumes
associ-ated with the analytical samples are smaller
thanthe totalrecoveryfromthe combinedsite
investigations.
ComponentFunction
InterpretationoftheMorroBayfaunacannotbe disassociatedfrom the roleof sitesinregional settlementsystems,giventhatanychangeinthe characterofsiteusecouldcontributetovariation intherelativefrequencyoffaunalspecies (Bin-ford 1978, 1980).Weevaluatedsettlement
func-tionbyconsideringtherangeanddiversityof
cul-turalmaterialsrecoveredfromeachcomponent,
thepresence/absenceofburialsorotherfeatures,
the volumetric density of formal andinformal
artifacts,theratiosofflakedtogroundstone,and theevidenceforseasonality(remainsof migrat-inganimals[Figure2]andseasonallyavailable
plant foods). We evaluated assemblage
diver-sity statistically using the Margolef Diversity Index.
Results
Analysis identified 15 temporal components
from the more substantive earlier excavations
atMorroBay(CA-SLO-165,CA-SLO-215,and
January February March April May June July August September October November December
AQUATIC BIRDS
Greater white fronted goose
Redhead duck
Rednecked grebe
Black-legged kittiwake
Eared grebe
Canvasback
FISH
Bat ray
Shiner perch
Striped seaperch
Pile perch
Pacific hake
Redtail surfperch
MARINE MAMMAL
Northern fur seal
California sea lion
Figure2.MigratoryspecieswithseasonallyrestrictedappearancesatMorroBay.
LosOsosWastewaterproject.However,several
componentslackedadequatesamplesforcertain
constituents,asspecifiedbelow.
BirdsandMammals
Thirteencomponentsprovidedthesampleofbird
and mammal remains (Supplemental Table 1).
The Middle-period component from
CA-SLO-165producedveryfewbones,andthelarge
verte-brateremainsfromCA-SLO-977areunreported.
The total from the remaining 13 components
excludesremainsofallsmallburrowinganimals (e.g.,Botta’spocketgopher[Thomomysbottae]
and California ground squirrel [Spermophilus
beecheyi]), most of which are probably
intru-sive.The sampleincludes26speciesofducks,
geese, and other aquatic birds; 18 species of
marine birds; 6 terrestrial birds; 12 terrestrial
mammals;and6marinemammals.Overall,the
birdsandmammalsaredominatedbyterrestrial
mammalsthataccountfor65.5percentofNISP.
Dominant species are rabbits (Sylvilagus spp.;
NISP = 1075; 44.3 percent) and black-tailed
jack rabbit (NISP = 196; 8.1 percent). Mule
deer (Odocoileus hemionus), which was the
most abundant species inthe faunal collection
from Diablo Canyon and figured prominently
indebates aboutlarge gamehunting strategies
alongthecentralcoast(Hildebrandtetal. 2010;
Jones and Codding 2010), is decidedly less
abundantatMorroBay,representingonlyseven
percent(NISP=170)ofthebirdandmammal
inventory. The low frequency of deer and the
large numberof rabbits andhares almost
cer-tainlyreflecttheabundanceofsagebrushshrub
vegetationatMorroBay.
The number and diversity of bird remains
fauna and reflects the importance of the
estu-ary as a bird habitat. Ducks, geese, andother
aquaticspeciesmakeup19.4percent(NISP=
446)ofthecollection,followedbymarinebirds
(NISP=270;11.1percent).Mostabundantare
grebes(Podicepsspp.;NISP=144;6percent)
and brown pelicans (Pelecanus occidentalis;
NISP=78;3.2percent).Fewerbirdboneswith
less species diversity were reported from the
exposed rocky coast at Diablo Canyon to the
south(Jonesetal. 2008)
Marine mammals, dominated by sea otter
(NISP =59;0.4percent),are relatively
unim-portant in the Morro Bay collection, making
up less than 3 percent of NISP. This too
contrasts with the Diablo Canyon open coast,
wheremarinemammalsaccountedformorethan
21 percent of the identified bird and mammal
remains.
Ofparamountimportance,however,are
pat-terns across time (Figure3). Most striking in thisregardisvariationintherelativeimportance
ofterrestrialmammals.Throughoutmostofthe
sequence, terrestrial mammals, predominantly
rabbits and hares, account for no less than
69percentof the non-piscinevertebrate fauna. However,duringtheMiddle-LateTransition,this
figureplummetstoonly14.2percent,dominated
bycottontailrabbits(NISP =44).Atthesame
time,deerreachalowof1percent(NISP=5). Replacingterrestrialgameinimportanceduring thisintervalareaquaticandmarinebirds,which togetheraccountfor84percentofthenon-piscine
assemblagefor Middle-Late TransitionPeriod.
This dearth of terrestrial mammals, combined
with the high frequency of marine birds,
rep-resents aprofoundlydifferent patternthan that ofanyotherintervalinthe8,000-yearsequence, withaquaticbirdsbeingthreetimesmore
numer-ous than at any other time. Although marine
mammals remainedinsignificant (1.5percent),
the non-piscine remains show a striking shift
toward marine species during the Middle-Late
Transition. Following the end of this period,
terrestrialspecies againdominate(70percent), andmarine/aquaticbirdsreturntothelowlevels typicalfortherestofthesequence(25percent). Theheavyemphasisonaquaticbirdsandrabbits,
which together account for 95 percent of the
Middle-Late Transition non-piscine vertebrate
remains, suggests little if any reliance on
thebowandarrowforhunting,giventhatthese animals,especiallythe birds,weremorelikely trappedorsnared.Projectile pointsizeprofiles indicate, fairly convincingly, that the bow and
arrow arrived to the central coast during the
Middle-Late Transition or slightly earlier (ca.
1050calB.P.).ThisisconfirmedatMorroBay,
wherethesamecomponentsthatyieldedthe
rab-bitandbird-dominatedfaunalassemblagesalso
produced arrow-sized projectile points, albeit
in very small numbers (Far Western
Anthro-pological Research Group 2016). While the
appearanceofthebowandarrowmighthavebeen
associated with increased intergroup conflict
(Kennettetal. 2013;Lambert 1994),itinitially had little effect on subsistence hunting
strate-gies. This supports an idea advanced by Brill
(2014)thatthetechnologymayhavebeenused
morefor inter-humanconflict thansubsistence
in southern California. However, there is no
complementaryburialrecordfromMorroBayor
surroundingareasrobustenoughtocomparethe
faunalrecordwithskeletalevidenceforprojectile violence.
Findings from another recently identified
Middle-LateTransitionPeriodcomponent
pro-videsomesupportfortheheavyrepresentation
of marine animals in faunal assemblagesfrom
thisinterval around Morro Bay. CA-SLO-239,
nearthecurrentmouthofthebay,wasexcavated
in 1961 (Clemmer 1962), but its chronology
was unclear until the first radiocarbon dates
fromsitematerialswererecentlyreported(Jones
et al. 2017). Dates and temporal diagnostics
showclearlythat thesitewasinhabitedduring
the early Middle and Middle-Late Transition
periods.Faunalsamplingstrategieswerenot
con-sistent with current standards, andcomponent
definitionisimprecise,butthefaunalcollection
is nonethelessdominated by marine mammals
(NISP =39; 78 percent),including California
sealions(Zalophuscalifornianus; NISP=13)
and sea otters (Enhydra lutris; NISP = 13).
Unfortunately, owing to the era during which
the site was investigated, fish bones were not
collected, but the marine focus in the large
vertebratesisconsistentwithfindings fromthe
other Middle-Late components in the current
(a) Percentage of Marine/Estuarine Birds
90 80 70 60 50 40 30 20 10 0
Millingstone/ Lower Archaic
(b) Fish NISP/m³
1600
1400 1200 1000
800 600
400 200 0
Millingstone/ Early Middle Middle-Late Late
Lower Archaic
(c) Fish NISP/Deer + Rabbit NISP
1600
1400
1200 1000
800
600
400
200 0
Millingstone/ Early Middle Middle-Late Late
Lower Archaic
(d) Shellfish Weight (km)/m³
25
20
15
10
5
0
Millingstone/ Early Middle Middle-Late Late
Lower Archaic
Early Middle Middle-Late Late
Fishes
Gobaletidentifiedatotalof19,235fishbonesto ameaningfultaxon(generallyfamilyorbetter)
from an analytical volume of 127.1 m3 from
15components(SupplementalTables2and3).
The only sample available for one component
(the Middle-Late Transition at CA-SLO-458)
was recovered via wet-screening, which
typi-cally yieldshigher frequenciesof fish remains
than the dry-screening (Jones, Gobalet, and
Codding 2016) used at all other sites. Three
families/speciesdominatetherecordthroughout thesequence:surfperches,(Embiotocidae),
her-rings (Clupeidae), and New World silversides
(Atherinopsidae).Notsurprisingly,these
assem-blages varyconsiderably from thoseof Diablo
Canyon to the south, which was dominated
by open rocky coastfishes (Fitch 1972; Jones
et al. 2008). Surfperches include species that canbe taken eitherwithnets or as individuals withhooks/gorges.Herrings(includingsardines)
and silversides are small schooling fishes that
aremuch morecommonlytakenwithnets,the
formeroftenwiththeaidof watercraftandthe latterfromshore(Boone2012;Gause2002;Love
2011;Salls 1988).Thedominanceofsilversides
andsurfperchesthroughouttherecordsuggests
thatfishingwasundertakenwithnetsthroughout theHolocene.Thisissimilartofindingsreported
by Rick and Erlandson (2000) for the Santa
Barbaramainlandtothesouth.
While this singular emphasis on netting
smallschoolingfishisapparentthroughoutthe
sequence,thereisevidenceforvariationthrough
time in the relative importance and intensity
of fishing—again withafocus on the
Middle-Late Transition Period. Volumetric densities
of fish bone (NISP/m3) show relatively little
change from the Millingstone/Lower Archaic
through Middle periods (Table3), but amajor
increasecanbe recognizedduringthe
Middle-Late Transition, followed by a decline during
theLateperiod.Ratiosof fish/(deer+rabbits)
alsoshow anall-time apex duringthe
Middle-LateTransition.Togethertheseindicessuggest
a major increase in the importance of fish in
the diet relative to terrestrial mammals
dur-ing the Middle-Late Transition. Although the
fish remains from one of the two components
that marks the Middle-Late Transition Period
wererecoveredviawet-screening,bothsamples
exhibit high densities of fish bones with the
dry-screenedsamplefromCA-SLO-457actually
showingthehighestdensity.
Not included in the current study are fish
remains recovered from 1/16-inch mesh
wet-screenedcolumnsamples.Reportedelsewherein
areportexclusivelyonthepiscinefaunalremains
from Morro Bay, the column findings show
consistentrecovery of tinyfish bonesfrom all
components(Jones,Gobalet,andCodding 2016; Jonesetal. 2016).Thissuggeststhattaphonomic preservationissuesarenotasignificantproblem
orinfluenceontheassemblages.
Shellfish
Thirty-threespeciesofshellfishfrom14 compo-nentsrepresentthreehabitats:estuary/bay,open rockycoast,andopensandycoast(Supplemental
Table 4). Estuarine habitats were immediately
adjacenttoallsitesandrequiredminimaltravelto exploit.Openrockycoastenvironmentwas
avail-ableatthemouth(MorroRock)andoutsideof
thebayandwouldhaverequiredmodesttripsof
2–6km(probablyinbalsacanoes).Opensandy
coasthabitatwasavailableonthewindwardside
of the sand spit that separates the embayment
from the open waters of Estero Bay. In light
of these spatial distinctions, all of the
com-ponents were dominated by estuarine species,
specifically clams (littleneck clam [Leukoma
spp.],Pacificgaperclam[Tresusnuttallii],
Wash-ingtonclam[Saxidomusnuttalli],andmacoma
clam [Macoma spp.]), andthe California oys-ter (Ostrea lurida). The relative abundanceof oysterswithinMorroBay,especiallyduringthe lateHolocene,isadistinguishingfeatureofthis
estuary relative to other similar environments
elsewhere inCalifornia. Also distinctiveis the
absence of protected habitat mussels (Mytilus
trossulus), which are common in less isolated estuaries tothe northandsouth.Mussel shells
were relativelyabundant in somecomponents,
but all represented the exposed coast species,
Mytiluscalifornianus.
Themolluscanremainsexhibitcomplex
vari-ation that reflects the evolution of the
Table3.FaunalIndicesfromMorroBayTemporalComponents.
NISP N Margolef
Fish Birds Species Diversity Fish/ Shell
Site Fish NISP/ and Birdsand Birdsand NISP NISP Deer+ wt(km)/
3 3
CA-SLO- Period NISP m Mammals Mammals Mammals Deer Rabbit Rabbit m
23 Late 3,907 372.0 405 43 6.833 46 158 19.15 26.4
626 Late 837 71.5 218 15 2.416 1 188 4.43 14.0
Subtotal/mean 4,744 213.6 623 46 6.994 47 346 12.07 19.5
457 Middle-Late 7,041 1,354.0 451 36 5.727 4 47 138.1 34.9
Transition
458 Middle-Late 9* 128.6 7* – ∗ ∗ ∗ ∗ 5.3
Transition
Subtotal/mean 7,050 1,337.8 458 36 5.727 4 47 138.1 17.9
14 Middle 2,294 124.7 487 21 3.232 12 439 5.08 3.5
165 Middle 25 20.8 ∗ ∗ ∗ ∗ ∗ ∗ 33.3
812 Middle 107 36.9 53 13 1.259 4 37 2.53 7.2
Subtotal/mean 2,426 60.8 540 28 4.291 17 476 5.09 9.5
23 Early 2,916 199.7 204 30 5.453 13 82 32.94 14.9
165 Early 588 16.7 262 23 3.951 56 117 3.58 77.9
458 Early 31 3.44 10 4 1.563 0 8 4.00 7.6
812 Early 142 67.5 73 12 3.729 16 35 3.17 7.4
977 Early 218 226 – – – – – – –
Subtotal/mean 3,895 102.7 549 44 6.816 85 242 11.9 16.5
165 Millingstone/ 404 4.9 25 9 2.486 2 5 9.57 69.3
LowerArchaic
215 Millingstone/ 603 137.0 148 16 3.001 7 135 4.24 7.6
LowerArchaic
812 Millingstone/ 113 27.3 84 12 2.483 12 57 1.63 10.8
LowerArchaic
Subtotal/mean 1,120 88.2 257 25 4.334 21 197 5.13 11.7
Grandtotal 19,235 2,427
∗Recoveredviawet-screening.
importance of shellfish in the diet over time.
Millingstone/LowerArchaic–periodpeople
col-lected shellfish in modest amounts from
rela-tively circumscribed foraging areas limited to
estuarinehabitatsimmediatelyadjacenttoliving sites.In thenorthernreachesofthebay, where
sands had accumulated by 8,100 years ago,
collection focused on white sand clams,while
tothesouthatCA-SLO-812,oystersdominated
the earliest shell remains. Shellfish collection increasedsubstantiallyattheonsetoftheEarly
period, when Morro Bay was larger than it is
today, prior to late Holocene infilling. While
thequantityofcollectedshellincreased,oyster declinedinimportance inthe southofthe bay, andexploitationofrockycoastspeciesincreased. The lattersuggeststhatthe foragingradiusfor
shellfishwidened, whilethe decrease inoyster
suggestsongoing accumulation of silty/muddy
sediments (not favored by oysters) within the
bay. Exploitation of shellfishdecreased during
the Middleperiod, atwhichtimeuseof rocky
coast species reached an all-time high at the
expense of estuarine species, which reached
a Holocene nadir. The Middle-Late Transition
showsasubstantialincreaseinshellfishharvest, consistentwithtrendsfromthevertebratefauna atthattime.Oysterswereagainimportantatleast
inthesouthernportion ofthebayat
CA-SLO-457.Unlikethe vertebrates,shellfishincreased
further during the Late period, even though
sedimentsbythattimehadcompletelyfilledin
anddecreased the size of the estuary.Overall, themarkedupturninshellfishcollectionduring
the Middle-Late Transition is consistent with
otherfaunalevidenceforincreaseduseofmarine foodsduringthetimeofthemedievaldroughts. Itisimportanttorecognize,however,thateven
greater shellfish harvests were made after the
marine subsistence was not necessarily at its absolutepeakduringthedroughtsinterval.
ComponentFunction
Samplesizesweretoosmalltodrawfirm
con-clusionsaboutthe functionoftheEarly-period
componentatCA-SLO-977ortheMiddle-period
componentatCA-SLO-165,butthe13
remain-ing components show diverse artifact
assem-blageswithsimilarfrequenciesofflakedstone,
groundstone,andboneimplements
(Supplemen-tal Table5). Flakedstone toolproduction was
evident for all components as well. Projectile
points, ground stone, and bone tools show no
meaningfulvariationovertimeintheir volumet-ricfrequency.Thesesimilaritiessuggestthatall
of the components served as residential bases
ofsometypethroughoutthesequence,although
somevariationisapparentinthehumanburials,
shell,androckfeatures,whichweremore
com-monatcertainsitesbeginningintheEarlyperiod.
The presence of these features suggests that
someresidentialsiteswereoccupiedforgreater
portions of the year from this point onward,
andthattheoverallsettlementstrategyinvolved long-term and short-term residential sites(Far
WesternAnthropologicalResearchGroup2016).
Nonetheless,thediverseassemblagesatallstudy
sites imply that the range of tasks pursued at
long-term and short-term residential sites was
fairly similar. Thereis nothingtosuggest spe-cializedfunctionssuchasprocessinglocations, stations,or caches.Thisisnottosaythat such
sitetypeswerenot used locally,as manyhave
suggested(e.g.,Bertrando2006;Farquhar2003), but rather that these specialized functions are notrepresentedinthecurrentsample.Ratiosof
bifaces/groundstone suggest amodest increase
in the importance of the latter late in time
but not enough to indicate wholesale change
in site function. Beads also show a modest
increasebeginningintheMiddle-LateTransition ca. 1000 cal B.P., but there is little reason to
think that this alone represents major change
in the residential nature of the occupations.
Importantly,theabsoluteandrelativefrequencies
of ground stone implements, bone tools, shell
beads, features, and human burials from the
Middle-LateTransitioncomponentat
CA-SLO-457 demonstrates the residential character of
this occupation. In sum, there is every reason
to believe that the components were similar
enoughthatfunctionalvariationwasnotamajor contributortodiachronicvariabilityinthefaunal assemblages.
HabitatVariability
Thecomponentswithsubstantivefaunal
assem-blages are situated adjacent to a variety of
micro-habitatswithinandaroundtheMorroBay
estuary.Inadditiontovariedmolluscanhabitat discussedabove,Fierstineetal.(1973)defined at least four different fish habitats within the
bay. Among the fish remains, findings from
CA-SLO-977 show frequencies of Pacific
staghornsculpinandjacksmelthigherthanany
othercomponentinthesample.Theprevalence
ofthesefishesalmostcertainlyreflectstheunique
location of CA-SLO-977 on the Morro Bay
sand spit (Jones, Gobalet, and Codding 2016;
Jones et al. 2016). The possibility exists that otherhabitat-relatedvariabilitycouldcontribute tothediachronicpatternsinthefaunalremains, particularlyinlight of the factthat the current
sampledoesnotincludecomponentsassociated
withallmicro-habitatsforalltimeperiods.While suchapossibilityneedsconsiderationinfuture work,otherreasonssuggestthatthediachronic
patterns delineated above reflect response to
climatechange,notmerelyspatialvariation.Four
ofthesitesthatproducedkeycomponents,
CA-SLO-23,CA-SLO-457,CA-SLO-458,and
CA-SLO-626arelocatedwithin500mofoneanother
adjacenttothe samepartof thebay.
CA-SLO-23andCA-SLO-457areseparatedbylessthan
100 m, and produced similar residential tool
assemblages.Thethreecomponentsatthesetwo
sites(Early, Middle-LateTransition,andLate)
exhibit the strong shift to a marine resource
focus that we believe was the general pattern
forbehavioraroundthebayduringthisinterval.
Furthermore, findings from other components
show uniformity acrossfish habitatzones.For
example,theEarly-periodcomponentsfrom
CA-SLO-165atthemouthofthebayand
CA-SLO-812 at the back of the bay are both heavily
dominated by surfperches as is the
Milling-stone/Lower Archaic component at
Seasonality
Remains of migratory animals suggest
varia-tiongenerallyconsistentwithcomponent
func-tions.High frequency of bat rayremains from
the Millingstone/Lower Archaic component at
CA-SLO-812 suggests that the short-term
res-idential occupation here was focused on the
summermonths (Table4).Mostsitesoccupied
afterthatperiodshowabroaderseasonalrange
of occupation, although these indicators are
absent fromCA-SLO-458,eventhough a
rela-tivelyrobustartifactassemblagewasrecovered
fromthatsite. TheEarly-periodcomponentsat
CA-SLO-23 and CA-SLO-812 show four of
thesix wintermigratorybirds,butinrelatively
low numbers (NISP = 11; 9.2 percent). Bat
rays are still dominant (NISP = 64),but their
relative abundance decreases to 53.8 percent.
Pileperchandmarinemammalsincrease
signifi-cantly(NISP=44),representing37.0percentof
theassemblage.Thecombinedfindingssuggest
thatoccupationoccurredduringallseasonsofthe
year, whichisconsistent withthe morerobust
nature of the artifact assemblages associated
with the Early-perioddeposits atCA-SLO-23,
CA-SLO-458,andCA-SLO-812andthehigher
frequencyof featuresandburials.Multi-season occupationisalsoapparentfortheMiddle-period components.ThecriticalMiddle-LateTransition
componentatCA-SLO-457differsfromothers
in that it shows multi-season occupation, but
also a very heavy emphasis on fall, winter,
andspring species.Thisis consistent withthe
greater reliance on marine oriented birds. The
LatePeriodshowsmodestdeclinesinfall-spring
indicators, which is consistent with decreased
emphasisonwinter-migratingmarinebirds.
Conclusions
Arobust collectionofmammal, bird,fish,and
shellfish remains from an 8,000-year
residen-tial sequence at Morro Bay shows a decided
focusonmarinespeciesduringtheMiddle-Late
Transition cultural phase (950–700 cal B.P.),
whichlargelycoincideswiththeMedieval
Cli-matic Anomaly. This is consistent with
find-ings from the Santa Barbara Channel 100 km
to the south, where research on the droughts
hasalonger,moreextensivehistoryandwhere
a heavy marine subsistence focus was first
recognizedasanapparentresponsetomedieval
drought (Kennett and Kennett 2000). Previous
faunal studies from central coastal California
provide modest evidence for increased fishing
(Codding and Jones 2007; Joslin 2010) anda
markedincreaseinrabbitexploitation (relative todeer)duringtheMiddle-LateTransitiononthe
exposed coastsof centralmainland California,
but the Morro Bay findings indicate that this
estuarinesettingservedasadistinctive
marine-focusedsubsistencerefugiumduringtheMCA.
Due to a preponderance of shrub vegetation,
rabbits dominate the entire 8,000-year Morro
Baysequence,makingthedeer/rabbitratioless sensitiveinthis setting,althoughdeer remains didreachanotablelow(NISP=7;1.5percent) duringtheMCA.Moretellingisanall-timepeak
in marine andestuarine birds,which is
three-timeshigherduringtheMiddleLateTransition
thanany otherperiod inthe sequence. Similar
apices are apparent in fish NISP/m3 and fish/
deer+rabbits,allofwhicharestrikingintheir
degree of variance and abundance during this
criticalintervaloftime.Alloftheseindicesalso showdeclinesinmarinefocusduringtheensuing LatePeriod,whenclimateamelioratedduringthe colder,wetterLittleIceAge.
The heavy reliance on fish, aquatic birds,
rabbits,andshellfishduringtheMCAsuggests
thatuseofthebowandarrowhadlittleeffecton
thepursuitoffood,eventhoughsmallnumbers
of arrow-sizedprojectile pointsappearinlocal
middensfor thefirsttimearound1000calB.P.
Thetechnology mightwellhavebeeninvolved
in intergroup conflict but, unlike areas to the
north(Schwitallaetal.2014)andsouth(Lambert
1994), the Morro Bay area does not have a
skeletal record substantive enough to evaluate
suchapossibility.
Shellfish remains show a decided increase
during the Middle-LateTransition, but, unlike
the vertebrate fauna, increase further after the
MCAduringtheLateperiod.Thissuggeststhat
marinefoodswerenottappedtothemaximum
duringthe Medievalperiodandis further
con-sistent witharecentevaluation of theregional fisherythatshowedthatitwasneversignificantly
impacted by regular Native harvest during the
Holocene (Jones, Gobalet, and Codding 2016;
Jonesetal. 2016).Thesefindingsindicatethat,
whiledroughtinfluenceddecision-making,
sub-sistenceeconomiesinthissettinghadnotreached crisismode,atleast notfortherelativelylarge blocksoftimethatcanpresentlybedistinguished inthemiddenrecord.Nonetheless,theviability
of thefood baseduringthe MCAisconsistent
with the record of dental caries in the San
FranciscoBayarea(SchwitallaandJones 2012),
whichsuggeststhat peoplethereweatheredthe
droughtsthroughheavyrelianceonstoredfoods richincarbohydrates, likelyacorns.Continued
evaluationof themedievaldroughtshypothesis
needs to critically examine evidence for the
characterofactualresponsesandtosortoutonan interregionalbasisthedegreetowhichtheperiod
can be accurately characterized as a time of
crisis.MorroBay,withaproductive,sustainable
marine foodbase,wasalmostcertainly notthe
only such refugium; the presence and extent
of othersneedtobe carefullyevaluated, as do possiblelocationswherefoodoptionsweremore
constrainedbydroughtandproblemsweremore
severe.
Acknowledgments. WethankNicoleBirneyforpreparation
ofFigures1and2.WealsowishtothankKateBallantyne
forherlong,capableoversightoftheLosOsosWastewater archaeologicalproject.TheSpanishabstractwascheckedby AntonioRodríguez-Hidalgo.
SupplementalMaterials. Supplementalmaterialsarelinked
totheonlineversionofthepaper,accessibleviatheSAA memberloginathttps://doi.org/10.1017/aaq.2016.31.
SupplementalTable1.SummaryofBirdandMammal RemainsfromMorroBaySites.
SupplementalTable2.FishRemains(NISP)fromMorro Bay Components, Millingstone/Lower Archaicand Early Periods.
SupplementalTable3.FishRemains(NISP)fromMorro BayComponents,Middle,Middle-LateTransition,andLate Periods.
SupplementalTable4.ShellRemains(Weightingrams) fromMorroBayTemporalComponents.
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