Evidence from Buhais Rockshelter for human settlement in Arabia between 60,000 and 16,000 years ago

Domain: biology
Published: 2026-03-23
Editorial outcome: major_revision

Abstract
Severalsignificantmilestonesinhumanevolutiondatetotheperiodbetween
70,000and12,000yearsago,includingthereplacementofarchaichumans,
theglobaldispersalofHomosapiensandtheintroductionofUpperPalaeo-
lithictraditions.TheArabianPeninsulaprovidesonlysparserecordsillumi-
natingthisperiod.WeintroduceheretheBuhaisRockshelterarchaeological
sequenceandpaleoenvironmentalrecordsfromtheFayaPalaeolandscapein
theEmirateofSharjah(UAE).BuhaisRockshelterprovidesstratifiedstone
artifactassemblagesreflectinghabitationphasesaround125,000,59,000,
35,000and16,000yearsago.Palaeoenvironmentalfieldworkfurthershows
thatsettlementatBuhaisRockshelteriscontemporaneouswithincreased
wateravailabilityinthelandscapeatthesetimes.Ourresultscontradictthe
prevailingviewofhumanabsenceinArabiaattheendofthePleistoceneand
callforreassessingtheinhabitabilityofsouthernArabiaduringthelastglacial
period.ResultsfromBuhaisRockshelterextendknownrecordsfromJebel
Fayaanddemonstraterepeatedoccupationoftheregionbetween210,000
and16,000yearsago.Together,thiscontributesdataforacriticaltimeframe
inhumanevolutionprovidinganempiricalfoundationfortestinganthro-
pologicalmodelsabouthumanadaptationtoanddispersalthroughthedesert
landscapesofsouthernArabia.

Introduction
Recent evidence from the Arabian Peninsula has substantially Palaeolithic(LMP).WadiSurdudinYemenandal-Marrat3innorthern
advanced understanding of the region’s early prehistory1–6. Archae- SaudiArabiaprovideevidenceforhumanoccupationofthePeninsula
ologicalrecordsdocumentinghumanoccupationduringwetphasesof around 60–50ka ago3,7. This period is of particular importance for
MarineIsotopeStage(MIS)5areparticularlywellrepresented(Fig.1). humanevolutionaryhistory,asgeneticevidencesuggeststhatthefinal
Incontrast,sitespost-datingMIS5areexceedinglyrare.Asaresult,the successful expansion of modern humans into Southwest (SW) Asia
timingandnatureofhumanpresenceontheArabianPeninsuladuring occurredatroughlythesametime8.

In addition to questions surrounding global human dispersal, anothermajorevolutionarymilestoneremainspoorlyrepresentedin
thearchaeologicalrecordoftheArabianPeninsula:theemergenceof
Upper Palaeolithic (UP) traditions. In the Southwest Asia, early UP industries are dated to approximately 50ka and 35ka9–11. To date
MatafahinsouthernOman(Dhofar)istheonlysiteintheregionthat
providesbothchronometricdatesandalithicassemblagetypologi-
callyattributedtotheUP12.NositeontheArabianPeninsulacurrently
preserves stratified evidence spanning both LMP and UP periods, limitinginsightsintoculturalanddemographicdynamicsduringthis
criticalphaseofhumanevolution.

Here,wepresentevidencefromBuhaisRockshelter(UnitedArab
Emirates,UAE),partoftheUNESCOWorldHeritageSiteFayaPalaeo-
landscape,togetherwithdatafromadjacentareas,contributingtoa
more detailed understanding of terminal Pleistocene settlement in
Southeast (SE) Arabia. These findings provide insights into local
palaeoenvironmental conditions and regional habitability between
approximately 60–16ka. Our archaeological records document
humanoccupationjustbeforeandaftertheLastGlacialMaximum(ca.
20ka),aswellasthepresenceofafullydevelopedearlyUPindustryin
SE Arabia by ca. 35ka. Combined with palaeoenvironmental recon-
structions, these data indicate that SE Arabia remained habitable
during at least parts of the terminal Pleistocene and necessitate a
reassessmentoftheregion’sroleinmodelsofhumandispersalsand
adaptationtoaridenvironmentsduringperiodstraditionallyviewedas
hyper-arid.Ourresultsfurthersuggestregionallydistinctsettlement
dynamicsandchangingpatternsofspatialconnectivityamonghunter-
gatherergroupsoccupyingSEArabiaduringtheLMPandUPperiods.

Results
BuhaisRockshelterissituatedinthecentralregionoftheEmirateof
Sharjah(UAE),approximately60kminlandfromtheGulfcoastand
about 15km south of the palaeolithic site FAY-NE1 (Fig. 2) at Jebel
Faya13–15.IncontrasttoFAY-NE1,BuhaisRockshelterliesonthewestern
sideoftheFaya-Buhaisanticlineandfaciestheextensivesanddunesof
thenorthernRub’al-Khali.Thesiteislocatedabout800mtotheeast
ofthemainlocaldrainage,WadiIddayyah(Fig.2).

Themodernsheltermeasuresapproximately20minwidthand
between1.5mand2mindepth(Fig.2).ItisformedwithintheLate
CretaceoustoPalaeogeneMuthaymimaLimestoneFormationatthe
southernendofJebelBuhais.ThesiteisprimarilyknownforIronAge
burial remains, excavated during the 1990s16. In contrast, its Pleis-
tocene deposits remained unexplored until the present project,
which commenced with test excavations in 2017. Two 1×1m test
trenches revealed stratified lithic material, prompting a full-scale
excavationbeginningin2019.Overfourseasonsbetween2019and
2024,anareaof24m²wasexcavatedtoamaximumdepthof1.70m
(Figs.3,4).

Sitestratigraphy
Excavationrevealedthreegeologicalhorizons(GH)identifiedbased
on their composition and designated GH 1 to 3. GH 1 was further
subdivided into four sublayers (a-d), each exhibiting minor sedi-
mentologicaldifferences(Fig.4,SupplementaryFig.1).Alllayersare
inclined in accordance with the morphology of the underlying
bedrock.Largerockfallblockswereinitiallyremovedfromthecentral
partofthesitetoexposethefullexcavationarea.Withinthestrati-
graphic sequence,four distinctArchaeologicalHorizons (AHs) were
identified.ThePleistocenechronologyofthesiteisbasedonoptically
stimulatedluminescence(OSL)datingofninesedimentsamplescol-
lected from within and between the AHs (see Methods below and
SupplementaryFigs.10,11,SupplementaryTables5,6).

Thelowermostunit,(GH3),directlyoverliesthebedrock(Fig.4,
SupplementaryFig.1),isapproximately30cmthick,andcontainsthe
oldestarchaeologicalhorizonAHIII.TwoOSLsamplesfromthislayer
yield a mean age of 124ka±6ka (Buhais 3: 123±10 ka; Buhais 7:
125±9ka).Theoverlyingsediment,whichisdevoidofarchaeological
material, was dated to 95ka±9ka (Buhais 6). The subsequent unit,
(GH2),is25–30cmthickandcharacterisedbyabundantgravelsized
clasts(Fig.4,SupplementaryFig.1).Thissedimentisrelativelyloose
andpoorlyconsolidated.GH2containsAHII,datedtoapproximately
60kaago(Buhais4:59±5ka).

TheoverlyinglayersGH1dandGH1cformaclearlydefinedstra-
tigraphicboundaryseparatingGH2andGH1bandthusmarkingthe
transitionbetweenthesite’sMPandUPdeposits.GH1bisupto60cm
thick in the eastern part of the excavation and thins westward to
approximately 15cm. A thin concentration of lithic artifacts was
identifiedwithinthislayer.OneOSLsample(Buhais8)yieldedanage
of 35±3ka. GH 1a accumulated behind a large rockfall block,
restrictingitsspatialextenttotheeasternpartoftheshelternearthe
presentbackwall(Fig.4).TwoOSLsamplesfromGH1aindicateamean
depositionalageof35ka±5ka(Buhais1:30±2ka,Buhais9:41±2ka).
GH 1a contains the lithic assemblage designated AHIa(see Supple-
mentary Note 1: Site Information for details on the nomenclature).
GivenstatisticallyindistinguishableagesofGH1bandGH1a,artefacts
fromGH1barecombinedwiththosefromGH1aandpresentedasa
singlearchaeologicalhorizon(AHIa).GH1representstheuppermost
PleistocenelayeratBuhaisRockshelterandwaspartlyexposedduring
theIronAgeexcavationsconductedinthe1990s.Thecentralpartof
the Palaeolithic excavation was initially sealed by large limestone
blocks resulting from overhang collapse. Following their removal,
lithicartifactsinundisturbedpositionbelongingtoAHIwererecov-
ereddirectlybeneath.GH1isapproximately40cmthick,increasingto
about50cminthewesternpartoftheexcavation.TwoOSLdatesfrom
this unit indicate a meandepositional age of 16ka ±2ka (Buhais 5:
14ka±1ka,Buhais10:17 ka±2ka).

MiddleandUpperPalaeolithiclithicassemblages
The lowermost AH III comprises a relativelysmalllithic assemblage
(n=213),whichneverthelessexhibitstypicallocalMiddlePalaeolithic
(MP)characteristics(SupplementaryFig.2).LithicproductioninAHIII
isgearedtowardsflakeproduction(SupplementaryTable1).Levallois
cores with unidirectional, bidirectional and centripetal preparation
were identified. There is also evidence for the presence of bifacial
reduction. The few retouched artifacts include tool types such as
notchedflakesandsidescrapersaswellasonesmallearly-stagebiface
(Supplementary Fig. 2). AH III resembles typo-technological char-
acteristics known from Jebel Faya assemblages AH VII, AH VI and
AssemblageC13,14.

TheLMPassemblageofAHIIcontains1039artifacts.Thetargetof
lithicproductioninAHIIwastriangularmorphologiesranginginterms
ofelongationfromshort,widetriangularflakestolargebladeswith
converging edges (Fig. 5). All flake and blade types show relatively
largebulbsofpercussionandrelativelythickstrikingplatforms,which
indicatestheuseofhardstonehammersfortheirproduction.Cores
feature very limited preparation. Considering technological
characteristics(seealsoSupplementaryFigs.3–7),thereisarangeof
MP flake and blade production systems evident, including semi-
rotatinglaminarandnon-Levalloisconvergentsystems.Evidencefor
classic Levallois reduction systems are notably scarce in AH II. The
often large and unprepared striking platforms, straight ventral sur-
facesandthelackofevidenceforLevalloisunidirectional-convergent
preparation indicates the preference for technological systems dis-
tinguishablefromtraditionalLevalloismethodsfortheproductionof
flakesandbladeswithpointedmorphologies.Tooltypologiesinclude
typical MP types such as notches and denticulates as well as side-
scrapers, and short atypical endscrapers (Fig. 5, Supplementary
Table 2). The observed characteristics of the AH II assemblage are
currently unknown from the stratified records of the region and
representtoourknowledgeanewtypeofMPassemblage.

IncontrasttotheflakeassemblagesfromAHsIIIandII,theUP
assemblageofAHIa(n=525)ischaracterizedbyasignificantfocuson
the production of elongated flakes, blades and bladelets (Supple-
mentaryTable1).WeobservethefirstoccurrenceoftrueUPbladeand
bladelet technologies in the sequence and in the region. Diverse
technologicalsystemsfortheproductionofbladesandbladeletsare
evident,includingbroadfacecorereductionandbladeletproduction
fromcoresonflake(Fig.6).Bladeproductionwascarriedoutusing
unidirectional-convergent reduction of single platform cores.
Unidirectionalparallelreductionofcoreswithtwoopposedstriking
platformswasanadditionallyobservedreductionstrategyforblades.
Strikingplatformsareoftenplainbutshowgrindingofedges.Blade-
letswereproducedintentionallyusingtwoindependentsystems.First,
therearesmallbladeletcoreswhereblankswereproducedfromthe
broadfaceofthecore(Fig.6:4).Second,coresonflakestypologically
classifiableascarinatedscraperandmultipleburinsprovideevidence
foradditionalindependentbladeletproductionsystems(Fig.6:5–6).
ThetoolassemblagecomprisestypicalUPtypessuchasendscrapers,
burinsandtruncations(SupplementaryFig.3,SupplementaryTable2).

TheUPassemblagefromAHI(n=1229)showsafocusonblade
and bladelet production, while flakes as end products play only a
minor role (Supplementary Table 1). Production of blades uses the
unidirectional-parallelreductionsystemcarriedoutonsingleplatform
cores(Fig.7).Strikingplatformsareingeneraleithercorticalorplain.
Obtainedbladeblanksarecharacterizedbyatleasttwoparalleldorsal
ridges, which demonstrates that laminar reduction surfaces were
regularly prepared by a series of blade or bladelet removals. Their
cross-sectionsaremainlytrapezoidal.Mostbladeblanksareretouched
usingdifferenttechniques,includingtruncationofbladeswithabrupt
retouchandbackingofbladeswithsemi-abruptretouch.Werecov-
eredseveralbackedbladeletswithabrupt/semi-abruptretouchfrom
AHI(Fig.7:5–7).Thelayer’stoolassemblagefurtherincludesUPtypes
suchasburins,endscrapers,truncations,oneunifacialtoolandone
biface(SupplementaryFig.3,SupplementaryTable2).

Palaeoenvironmentalresearch
ArchaeologicalfieldworkintheFayaPalaeolandcapehasconsistently
been accompanied by systematic palaeoenvironmental research17,18.
Tostrengthenthebasisforinterpretationsofthepalaeoenvironmental
contextofhumanoccupationintheareaduringtheLatePleistocene,a
4.70mdeepsedimentarysectionwasexcavatedatthenorthernendof
Jebel Faya (Fig. 2). Situated within the reconstructed extent of the
Mleha playa (following19), section P6 offers valuable palaeoenviron-
mentaldata.Inaddition,a1.70mdeepsectionwasexcavatedfroman
interdunalsiteatHuweimi(sectionR1)locatedclosetoWadiDhaid
(Fig.2),intowhichtheMlehaplayacatchmentfeedsasatributary.

SectionP6consistsofa4.7mthickstratigraphicsequencechar-
acterized by fluvial and alluvial sands and gravels characterising
channel flow, as well as sands and silts associated with low energy
standingwaterenvironmentsandepisodesofaeoliandunedeposition
(Fig.8,SupplementaryNote2).OnlytheresultsfromthePleistocene
partofthesequencearepresentedhere(Fig.8A,SupplementaryFig.8,
Supplementary Table 3). The lowermost sedimentary unit
(470–440cm;Facies7,Fl)iscomposedofcarbonate-rich,cemented
sandsandsilts.Small,containingminorophioliticgravelclasts,upto
5mmindiameterconcentratednearthetopoftheunit.Highcalcium
(Ca) and Ca:Si ratios (Fig. 8A, Supplementary Fig. 3) indicate an
increasedinputofcarbonatematerial.Thisfacieslikelyformedfrom
finesedimentssettlingoutofsuspensioninacalmlakeenvironment,
suggestinglow-energyconditionsduringtheexistenceoftheMleha
playalake.Thisunitwasdatedto>152±14ka(P6/2023-OSL1).Between
430–365cm,thisunitisoverlainbyagravel-richlayerdominatedby
harzburgiteclastscharacterisedbyhighconcentrationsofchromium
(Cr),nickel(Ni),iron(Fe),andelevated(Rb+Sr)/Tiratios(Fig.8;Sup-
plementary Fig. 8). The gravels are clast-supported, cemented by
hydromagnesite, and include pebbles and occasional small cobbles
within a sandy matrix.The base of thislayer is marked by a sharp,
erosionalboundary.Slightchangesinsandcontentcausesubtlecol-
our differences throughout the sequence. These gravels are inter-
preted as the result of high-energy, unidirectional fluvial flows
transportingsedimentfromtheHajarMountains.Theylikelyrepresent
channel lag deposits formed during periods of increased water dis-
chargewithinwadichannelsandadjacentareas.Asamplefrom370cm
yieldedanageof59±7ka(P6/2023-OSL2).

From365–330cm,thesequenceisdominatedbyawidespread
red aeolian layer (Facies 8, Sem), consisting of up to 98% fine to
mediumsand.Thisunitrepresentswind-blowndunematerialtrans-
portedfromtheRubal-KhalisandseatothewestofJebelFaya.The
gravellayerbelowit,richinharzburgiteclasts,isgeochemicallydis-
tinctandmarkedbyhighvaluesofCr,Ni,Fe,and(Rb+Sr)/Ti—aclear
geochemicalfingerprintofitssourceintheHajarMountains.Incon-
trast,thisoverlyingaeolianunitshowsasharpdropinthoseelements,
alongwithasignificantincreaseinSiandtheK/Caratio(Fig.8,Sup-
plementaryFig.8).Thesedimentsaremoderatelytowellsorted,with
sub-rounded to well-rounded grains, and feature faint pin-striped
bedding. A sample from this layer was dated to 39±5 ka (P6/
2023-OSL3).

Abovethis,from330–275cm,liesanothergravellayer(Facies1,
Gcm), composed of clast-supported, hydromagnesite-cemented
gravels dominated by harzburgite clasts. This unit is geochemically
distinct,withhighlevelsofCr,Ni,Fe,and(Rb+Sr)/Ti,andlowervalues
ofSiandtheK:Caratio(Fig.8,SupplementaryFig.8).Thegravelsare
interpreted as the product of high-energy flows during periods of
increasedwaterdischarge.Thebaseoftheunitismarkedbyasharp,
unevenerosionalcontactwiththeunderlyingaeoliansands.AnOSL
datefromthislayerindicatesanageof30±2ka(P6-13).Thesediments
above this unit are of Holocene age (Fig. 8A) and are not dis-
cussedhere.

The sediment sequence at Huweimi (Fig. 8C, Supplementary
Fig.9;SupplementaryTable4)recordsashiftfromaeoliantolacus-
trineenvironmentsduringtheLatePleistocene.Thebasalunit(R1–1)
consists mainly of coarse-skewed aeolian sand (~80%), indicating
wind-drivendepositiontypicalofinterdunesettings.Abovethis,finer
sediments(R1–2)dominatedbysiltandclayweredepositedinalow-
energylakeenvironment,reflectedbysymmetricaltocoarse-skewed
grainsizedistributions.Increasingironandstrontiumconcentrations
through this lacustrine unit suggest changing sediment sources or
geochemical conditions. Subsequent units (R1–3 and R1–4) show a
gradual increase in sand content and decrease in iron, indicating a
transition toward more energetic conditions and coarser
sedimentinput.

Theuppermostunits(R1–5 andR1–6)marka returntoaeolian
dominance, with sand content rising from 20% to 75%, reflecting
renewedwindactivityandlikelydrierconditions.OSLdatingplaces
the basal aeolian sands at around 16±1ka (HWM-2; Supplementary
Table6)andtheoverlyinglacustrinesedimentsat17±1ka(HWM-1),
indicating rapid sedimentation and a brief lake phase between two
aeolianepisodes.ThispatterncorrelateswithregionalLatePleistocene
fluvialactivationinWadiIddayyah(~17–16ka),highlightingdynamic
environmentalchangesdrivenbyclimaticfluctuationsduringthis
period18.

Methods
Archaeological excavations and sampling for palaeoenvironmental
andchronometricanalyseshavebeenconductedwithpermissionby
theSharjahArchaeologyAuthorityissuedtoKB.Exportpermissions
forgeologicalsampleshavebeenissuedtoKBandAGP.Handlingand
storageoffindsandsedimentsamplesfollowedrulesandguidelines
bytheinvolvedinstitutions.

Archaeologicalexcavation
BuhaisRockshelterislocatedatthesouthernendofJebelBuhaisfacing
tothe westtowardsthesanddune area,which providesprotection
fromthesuninthemorning(Fig.2).Thesiteprovidesashelteredarea
ofabout20mwidthand3mdepthandapotentialtotalhabitation
area of about 140m². The big blocks covering large parts of the
modern rock shelter area represent repeated roof collapse. These
blockspreservedabout1.7-meter-deepsediments.Thesiteislocated
justeasttoasmallwadithatdrainssurfacewaterfromitscatchment
area of about 25ha in southwestern direction towards Wadi
Iddayyah(Fig.2B).

Followingmodernstandardexcavationtechniques,wesetupa
localx-y-zgridusingatotalstationtoallowpieceplottingofallfinds
and features at <1cm precision in all dimensions. The grid was
roughlynorth-southorientedwiththex-axisbeingperpendicularto
thebackwalloftherockshelterandyincreasingtowardsnorth.The
excavatedareawassubdividedinto1×1mareas,eachnamedafter
their coordinates in the southwest corner (e.g. square 26/36 had
x=26mandy=36mcoordinatesinthesouthwestcorner).Excava-
tors dug in ¼ squares of these 1×1m areas following the natural
geological horizons. Archaeological (AH) and geological horizons
(GH) were defined during excavation. Hence, all finds and allsedi-
mentfromeverybucket,includinglaterfindsfromthesieving,were
assignedtooneAHandoneGH.Everyquartersquarewasexcavated
toadepthofabout3cm,whichfillsaboutone12lbucket.Theexact
depth reached with every round of excavation depends on the
sedimentscharacteristicsaswellasslopeandextendofthedefined
GHs. All buckets were sieved using 6mm and 2mm meshes to
recoverthesmallsizefractionofthelithicassemblage.Everyfindwas
pieceplottedusingaLeicatotalstation.Bucketsweremeasuredat
the centre point of the ¼ squares they were excavated from. The
latterallowsthesmallfindsthatwererecoveredduringthesievingof
thebucketstobelocatedwithinthequartermeterandatthecorrect
height. All measurements are recorded in a database during the
excavationusingtheEDMsoftwarekindlyprovidedbyS.McPherron
(https://github.com/surf3s/EDM).

Palaeoenvironmentalresearch
Sedimentologicalsampleswerecollectedfroma4.7mverticalsample
trenchprofileP6excavatedintheMlehaPlaya(Fig.8,Supplementary
TableS3).Thesequencecomprisedfluvialgravels,fluvialsandsand
silts and aeolian dune/sands. Lithofacies were described and differ-
entiated basedon sedimentological characteristicsand sedimentary
structures following different classification systems70,71. Sediment
samplesweresystematicallycollectedfromtheopentrenchfaceand
placedinziplockbags.

Huweimi(Fig.8)islocatedinthedunefield3.5kmnorthofthe
village ofArRashidiyya. Thisareacomprisesaseriesofsmallinter-
dunal playa basins separated bydune ridges, whichareup to20m
above the playa floor areas. The sampling site was found withinan
interdunalcorridor,whichextendedfor1.5kmx0.5km.Ontheeast-
ern flanks of the sub-basins, lake sediments have been eroded by
gulliestoformaseriesoflow,muddyyardangs.Theseareupto1m
highand5minlength.Thewesternsectionsofthesub-basinshave
beenerodedanddeflated.A170cmdeepsamplepitwasexcavated
andsamplescollectedat4cmintervals.

Sedimentbulkdensitywasmeasuredusingcalibratedbrasspots
following standard procedures72. Organic, carbonate and inorganic
contentsweredeterminedusingthelossonignition(LOI)methodat
e
550°Cand950°C.MagneticsusceptibilitywasmeasuredwithaBar-
tingtonMS2meterandMS2sensor,withsamplesovendriedat40°C,
weighedtotwodecimalplacesandmeasuredinreplicate.Valuesare
reportedasthemassspecificsusceptibility(χ )measuredas10-6m3kg-1.
lf
Forparticlesizeanalysis,sampleswereoven-driedat105°Cfor12h,
then disaggregated and sieved at 2mm, 1mm, 0.5mm, 0.25mm,
0.125mm, and 0.063mm. Additional grain size distributions
(0.02–2000μm) wereobtained by laserdiffraction using a Malvern
Mastersizer2000afterovernightsoakingina5%sodiumhexameta-
phosphate solution. Geochemical analyses of major and trace ele-
ments were performed non-destructively using two portable X-ray
fluorescence(pXRF)devices:anOlympusVanta(GeoChemcalibration,
8–40kV,automaticfilterselection)andaNitonXLTSeriespXRF.Ele-
mentsincludingCr,Ni,andFewereusedtotracefluvialinputfrom
ophiolite-rich sources in the Hajar Mountains, while Ca indicated
allochthonouscarbonatesandSirepresentedaeoliansiltsandsands.
Geochemicalratioswereusedtointerpretsedimentprovenanceand
weatheringintensity:Ca/Sitodistinguishbetweenautochthonousand
allochthonous carbonate73,74. Rb/Sr ratio to assess weathering and
terrigenousinputs75;(Rb+Sr)/Tiasagrain-sizeindependentproxyfor
chemicalweathering76;andK/Catoevaluateterrigenousvslacustrine
trends,withelevatedK-valueslinkedtoclaymineralsorK-feldspars
transported by fluvial or aeolian processes/aridification77. The full
sedimentologicalandgeochemicaldatasetisdetailedinSupplemen-
taryFigs.8and9.

Agedetermination
We used the optically stimulated luminescence (OSL) technique to
date the Buhais Rockshelter sequence and the palaeoenvironment
sections. OSL determines the last exposure to sunlight of quartz
mineralsfromthesedimentsthatcontainthearchaeologicalrecords
(see Supplementary Note 3: Age Determination for details). Con-
sidering the archaeological sequence atBuhaisRockshelter,we
systematicallysampledthesequenceduringthecourseoftheexcavation
in different areas within the excavation in 2018, 2019 and 2022
(Fig.3A).KeystratasuchastheUP-containingGHs1and1ahavebeen
repeatedlysampledfromdifferentpartsoftheexcavationtoensure
validityoftheresults.IntotalwecollectedtensamplesfromBuhais
Rockshelter.SampleBuhais2hasbeenexcludedheresinceitisfroma
stratigraphicpositionabovethesequencepresentedherelinkedtothe
Holocene occupation of the site. All produced OSL results are in
chronological order and correspond with the sequence of layer
deposition.

ConsideringthepalaeoenvironmentsectionP6,wecollectedin
total14 samples covering the entire 4.7m deep section (Fig. 8).All
sampleswereshippedtoandprocessedintheOSLdatinglabofthe
UniversityofFreiburg.

Sampling for OSL dating was carried out in the excavation by
collectingmaterialthroughexcavatingatnightusingredheadlights.
First,theouter,light-exposedlayerofabout5–10cmwasremoved.
Thesedimentextractedfromtheexposewassievedon-site(<2mm)
tosubstantiallyreducetheamountofmaterialforshipping,whichwas
transferred into opaque bags. For the palaeoenvironment sections,
opaquetubeswerehammeredintothesedimentandtransferredinto
black bags. A representative sample of about 200g from the sur-
roundings of each OSL sample was collected for high-resolution
gamma spectrometry (no sieving). The advantage of the latter
approachisthatitallowsforthedetectionofradioactivedisequilibria
intheUraniumdecaychain78–80.Suchdisequilibriacanoccurinsedi-
mentsrichincarbonate,astheresultofpost-depositionmobilization
relatedtopercolatingwater.AlossorgainofisotopesfromtheUra-
niumdecaycanproducesignificantageoffsets.

The radiation dose accumulated by the quartz grains since
deposition(D)wasdeterminedforsmall(1mm)aliquotsofquartz(ca.
e
50grains),veryclosetoasingle-grainlevel.About40–50aliquotswere
measuredpersampleforarchaeologicallayers,andca.20formost
palaeoenvironmentalsections.D distributionswereanalysedapply-
e
ing different statistical methods as explained in the Supplemen-
taryNote3.

Reportingsummary
Further information on research design is available in the Nature
PortfolioReportingSummarylinkedtothisarticle.

Dataavailability
Alldatausedinthispaperareprovidedinthemaintextandsupple-
mentaryinformation.Archaeologicalsamplesusedherearestoredby
theSharjahArchaeologyAuthority(SAA).Requestsforaccessshould
beaddressedtoSAA(info@saa.shj.ae).

Codeavailability
Luminescencedataanalyseswereperformedusingfunctionsimple-
mentedintheRpackage‘Luminescence’1.1.2.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "Comments on the manuscript “Evidence from Buhais Rockshelter reveals human settlement in Arabia between 60,000 and 16,000 years ago” by Bretzke et al.\nThis study reports OSL-based human occupations at ~125, 59, 35, and 16 ka at Buhais Rockshelter (Arabian Peninsula), challenging the previous Last-Glacial abandonment models and reframing Arabian habitability and human dispersal. It fits the scope of the NC, and could have wide readership. I will suggest major to moderate revision before publication.\nMy review centers on two pillars: (1) the robustness of the chronological framework that underpins all archaeological and palaeoenvironmental interpretations, and (2) the clarity and readability about field-wide significance and cross-disciplinary relevance expected by NC.\nFirst, the authors should strengthen validation of the OSL ages:\n1. The study’s chronology places substantial weight on statistical age models (MAM/FMM). While the authors explain key parameter settings (e.g., σᵦ), these models rest on specific assumptions and empirically set inputs. Model application should be guided not only by statistical grounds but also by the depositional context of each sample and any additional pertinent information (e.g., independent age control). Regarding De analysis, two major concerns need to be addressed:\nEnhance geomorphological justification for age model application. For example, the authors substitute MAM with FMM for sample BUHAIS3, hypothesizing three distinct grain input processes: aeolian influx (well-bleached), rock face weathering (unzeroed), and post-depositional mixing (younger mixing). While this reasoning is plausible, the processes proposed, e.g., weathering and bioturbation leading to discrete components, require dedicated discussion and empirical support from sedimentary or geomorphological evidence.\nThe absence of independent age control for cross-validation constitutes a significant weakness in the chronological assessment. The author should acknowledge this limitation or integrate independent chronological controls (if available) for validation.\n2. For the Dr calculation, the authors should provide a clear and evidence-based justification for the assumed water content values (e.g., comparison with regional moisture measurements, soil properties, or saturation limits used in similar regional studies) or explain the rationale for the assumed ranges (3±3% and 4±4%) – how did you integrate climate change and geological history into this value/error? What was the field water content in comparison?\nSecond, while the manuscript’s technical rigor is strong and detailed, the Discussion’s through-line seems fragment, diluting the translation of the chronological results into the narrative readability for capturing new noteworthy findings and perspectives. The through-line thereby requires strengthening.\nClarify a stepwise pathway for challenging Last-Glacial absence models: why the consensus held the interior to be unpopulated in hyper-arid periods (MIS 4/3/2), how stratigraphic scarcity and regional climate interpretations shaped that view, and how your 60–16 ka chronology reframes it via multi-pulses of terminal-Pleistocene occupation with short-lived hydrological conditions.\nOnce the core findings are sharpened, the compilation of dated archaeological sites should enable revisions to dispersal routes and late-Pleistocene settlement dynamics, which could be delineated further in both text and map. For regional comparison with “northern corridor” frameworks, a similar work of OSL-based MIS 5 Levant wetland corridors by Abbas et al. (2023, Human dispersals out of Africa via the Levant, Science Advances) would be helpful.\nMake the cross-disciplinary bridge explicit by showing how the Buhais sequence serves as an archaeological anchor for evaluating the hypothesized Basal Eurasian population; temper claims where evidence is indirect.\nA few missing references with OSL ages of Arabian water-lain sediments in the last glacial:\n1.Steffen Mischke et al., 2021. A Late Pleistocene Wetland Setting in the Arid Jurf ed Darawish Region in Central Jordan. Frontiers in Earth Sciences. doi: 10.3389/feart.2021.722435\n2.Bety S. Al-Saqarat, et al., 2020. A wetland oasis at Wadi Gharandal spanning 125–70 ka on the human migration trail in southern Jordan. Quaternary Research, https://doi.org/10.1017/qua.2020.82\n3.Abbas M et al., 2023. Human dispersals out of Africa via the Levant. Science Advances, https://www.science.org/doi/10.1126/sciadv.adi6838", "reviewer_2": "This manuscript reports new information from the Buhais Rockshelter in the United Arab Emirates. While the work reported is scientifically robust and has the potential to be significant, it comes across largely as a site report and it does not contribute a substantive, novel, argument or testing of hypotheses. For instance, take the title, ‘Evidence from Buhais Rockshelter reveals human settlement in Arabia between 60,000 and 16,000 years ago’. Given that several sites are already known in this time period in Arabia (e.g. SD-1, Matafah), what is fundamentally novel about the new findings? The most important part of the study is perhaps the discovery of Upper Paleolithic material – yet the authors say they are working on a separate paper about this (401), so not much information is given.\nCare is also needed with strawman arguments, namely they claim to “contradict the prevailing view of human absence in Arabia at the end of the Pleistocene”. The reference given for this is a paper about a speleothem record from Yemen. That paper argues wet periods facilitated dispersals into Arabia, but it is a strawman argument to claim that this study in particular, and the ‘general view’ more broadly, is that there were no humans in Arabia at the end of the Pleistocene. The work of Rose, Hilbert etc has long argued for a terminal Pleistocene human presence in southeast Arabia.\nSo while the study reports important findings, it does not seem like these are presented in a particular useful way, it is more like a site report with some vague indications of how the findings relate to things like adaptation to arid conditions and ‘distinctive patterns of settlement dynamics’ (page 3). Fundamentally, the story is seemingly one of repeated migrations into the area in association with wet periods. The authors argue against Late Pleistocene population continuity in Arabia. Instead, it looks like they have identified pulses of hominin dispersal into Arabia, largely correlating with those already known (e.g. SD-1 ca 60 ka, Matafah ca 33 ka). They are also present a somewhat contradictory argument by attacking the point that dispersals into Arabia correlate with wet phases, by saying their studies show the evidence of people in southern Arabia “during the presumably arid last glacial period”, but directly contradict themselves by finding that actually the periods of occupation correlate with “repeated reactivation of freshwater springs and hydrological systems”. What their findings suggest is that the European-derived glacial-interglacial dichotomy may not be the most useful framework for low latitude palaeohydrological change – as indeed many papers have argued in recent years. They themselves point out how actually the regional sequence of SE Arabia suggests human presence in association with Monsoon Index Peaks, when rainfall increased in the area.\nThe ‘nuts and bolts’ of the paper are good, such as the figures and the general descriptions of the deposits, their associated archaeological assemblages, and luminescence age estimates are all clearly presented and logical. The problem is the lack of orientation of the study to the key research themes in the region.", "reviewer_3": "The role of the Arabian Peninsula in the expansion of anatomically modern humans is a hotly debated topic in archaeological and palaeo-anthropological research. The “Southern dispersal route” is suggested by genetic evidence, but sound archaeological evidence is missing up to now. Therefore, any data from this region and this period of time is most welcome. Especially the absence of stratified deposits, covering the transition from Middle Palaeolithic to Upper Palaeolithic stone artefact traditions during the Late Pleistocene made any conclusions about this important step in human history impossible. Therefore, Buhais Rockshelter is a key-site with supra-regional relevance. The presented results are of utmost interest for the scientific community and an appropriate publication absolutely desirable. This leads me to my main point of criticism. In my opinion, the archaeological data on which these interpretations are based, are not presented in an adequate manner. With the exception of the total number of lithics of each archaeological horizon (AH) no numeric values are specified in the main text. Even in the Supporting Online Material, except for Fig. S2 and Table S1 no further information about the stone artefact assemblages is given. Table S1: Basic characteristics of lithic assemblages from Buhais Rockshelter, only shows values for the blank production. Some tables with metrical data and amount of tool-types, platform types etc. would be helpful and are in my opinion essential. The reader has to believe the description of the assemblages. But what does it mean that “Evidence for classic Levallois reduction systems are notably scarce in AH II”? Consequently, the results are not transparent and it is also not possible to compare the assemblages with assemblages from other sites.\nImportant results of the paper (and absolutely worth publishing) are:\n- the indication of a local Middle Palaeolithic tradition during times of high aridity is an important research progress.\n- evidence of human presence and inhabitable environments in SE Arabia during the last glacial period.\n- indications of a LMP population replacement.\nHowever, results and conclusions have to be verifiable and this demands a presentation of data. This has been done for the dating- and the palaeo-environmental section of the paper but is missing for the archaeological part. It should be easy to add this information (for example some tables in the SOM), but it is a requirement for publication.\nApart from that, there are only some minor questions and comments to specific text passages:\np.3, l. 3: mMarine iIsotope sStage (MIS) 5\np.6: “During the excavations, seven sediment layers were identified based on their composition and designated as Geological Horizons (GH) 1 to 3. GH1 was further subdivided into four sublayers (a-d), each exhibiting slightly different characteristics (Figs. 4, S1).” This is a little bit confusing. Rewording might help (During the excavations, three Geological Horizons (GH) were identified based on their composition and designated as GH 1 to 3. GH1 was further subdivided…….).\nFigure 4. Is the naming of the Geological Horizons correct (GH1, GH1a, GH1b & GH1c) Shouldn’t it be GH1a to GH1d?\np.8, l.4: Without reading the SOM, it is hard to understand the naming of AH Ia/I.\np.8: “All flake and blade types were produced by hard stone hammer percussion”. Why? What is the evidence for this?\np.8: “Tool typologies include typical MP types such as notches and denticulates as well as sidescrapers, and short atypical endscrapers.” How are notches and denticulates defined? What are the total numbers of tool types?\np.10: “The tool assemblage comprises typical UP types such as endscrapers, burins and truncations.” Numbers?\np.20: “Every quarter square was excavated to a depth of about 3 cm, which fills about one 12 l bucket.” What is the smallest excavation unit? Quarter square x 3cm? One 12 l bucket? And why “about 3 cm” and “about one bucket”? Shouldn’t it be “exactly 3 cm & about one bucket” or rather “about 3 cm & exactly one bucket”? Maybe, it is just my fallacy of thinking.\np.21: “Huweimi (Fig. 9) “. Fig. 9? Is this correct?"}, "author_response": "Response to reviewer questions and comments\nReviewer #1 (Remarks to the Author):\nComments on the manuscript “Evidence from Buhais Rockshelter reveals human\nsettlement in Arabia between 60,000 and 16,000 years ago” by Bretzke et al.\nThis study reports OSL-based human occupations at ~125, 59, 35, and 16 ka at Buhais\nRockshelter (Arabian Peninsula), challenging the previous Last-Glacial abandonment\nmodels and reframing Arabian habitability and human dispersal. It fits the scope of the\nNC, and could have wide readership. I will suggest major to moderate revision before\npublication.\nMy review centers on two pillars: (1) the robustness of the chronological framework that\nunderpins all archaeological and palaeoenvironmental interpretations, and (2) the\nclarity and readability about field-wide significance and cross-disciplinary relevance\nexpected by NC.\nFirst, the authors should strengthen validation of the OSL ages:\n1. The study’s chronology places substantial weight on statistical age models\n(MAM/FMM). While the authors explain key parameter settings (e.g., σᵦ), these models\nrest on specific assumptions and empirically set inputs. Model application should be\nguided not only by statistical grounds but also by the depositional context of each\nsample and any additional pertinent information (e.g., independent age control).\nRegarding De analysis, two major concerns need to be addressed:\nEnhance geomorphological justification for age model application. For example, the\nauthors substitute MAM with FMM for sample BUHAIS3, hypothesizing three distinct\ngrain input processes: aeolian influx (well-bleached), rock face weathering (unzeroed),\nand post-depositional mixing (younger mixing). While this reasoning is plausible, the\nprocesses proposed, e.g., weathering and bioturbation leading to discrete components,\nrequire dedicated discussion and empirical support from sedimentary or\ngeomorphological evidence.\n-> We thank the reviewer for pointing this out. However, in luminescence dating the choice of\ndifferent age models is generally based on statistical observations and there are dozens of\narticles describing and justifying this (e.g. Galbraith and Roberts 2012, Quat. Geochron.;\nChamberlain et al. 2018, Rad. Meas.; Peng 2021, Geochronometria). For sample BUHAIS3\nwe try to explain the origin of the D distribution. The reviewer asks for empirical evidence\ne\nproofing the hypothesis but without any suggestion how this could be done. One could\npossibly distinguish between grains of aeolian influx and rock face weathering by\ninvestigating these using scanning electron microscope images but very unlikely the ‘young’\ngrains (post-sedimentary mixing) that led to using the FMM instead of the MAM.\nThe absence of independent age control for cross-validation constitutes a significant\nweakness in the chronological assessment. The author should acknowledge this\nlimitation or integrate independent chronological controls (if available) for validation.\n-> We thank the reviewer for pointing this out, as it provides an opportunity to explain our\nsampling strategy in greater detail. Sampling was guided by the site’s sedimentological and\narchaeological stratigraphy. Over three different excavation seasons, we collected samples\nfrom different parts of the excavation area. The primary aim was to sample the same\narchaeological layer from different parts of the excavation from multiple locations. Particular\nemphasis was placed on layers containing archaeological material that is currently rare in SE\nArabia (e.g. UP archaeological evidence), while additional layers were sampled to\ncomplement the site’s chrono-stratigraphic framework. We argue that the fact that all OSL\ndating results are in correct chronological order and consistent with the site’s stratigraphy\nprovides strong support for the reliability of resulting chronological interpretation. Further\nsupport for our chronological interpretation is provided by archaeological horizon III, which\naligns closely, with results from Jebel Faya. In addition, comparison with records from\nadjacent regions indicate that the blade technology identified in the UP layers is fully\nconsistent with the proposed age range.\n-> To clarify this point, we have revised the methods section (page 23) as follows: “Key strata\nsuch as the UP-containing GHs 1 and 1a have been repeatedly sampled from different parts of\nthe excavation to ensure validity of the results. In total we collected ten samples from Buhais\nRockshelter. Sample Buhais 2 has been excluded here since it is from a stratigraphic position\nabove the sequence presented here linked to the Holocene occupation of the site. All produced\nOSL results are in chronological order and correspond with the sequence of layer\ndeposition.”\n2. For the Dr calculation, the authors should provide a clear and evidence-based\njustification for the assumed water content values (e.g., comparison with regional\nmoisture measurements, soil properties, or saturation limits used in similar regional\nstudies) or explain the rationale for the assumed ranges (3±3% and 4±4%) – how did you\nintegrate climate change and geological history into this value/error? What was the field\nwater content in comparison?\n->We agree with the reviewer that average water content during burial represents one of the\nlargest uncertainties in OSL dating but there is no approach that would allow to determine it.\nWe follow several previous studies (some now cited in the supplements) that used similar\nvalues, although none of those provided clear and evidence-based justification. Anyway, using\ndifferent water contents within a reasonable range (< 10 %) will change ages by not more\nthan 2-3 % and have no significant effect on the interpretation of the data. We have added\nsome remarks on this to the supplemental information.\nSecond, while the manuscript’s technical rigor is strong and detailed, the Discussion’s\nthrough-line seems fragment, diluting the translation of the chronological results into\nthe narrative readability for capturing new noteworthy findings and perspectives. The\nthrough-line thereby requires strengthening.\n-> We thank the reviewer for this constructive critique and agree that our previously chosen\napproach to discuss our findings could be improved to make it easier accessible for the broad\nreadership of Nature Communication. We follow the reviewer’s suggestions below and re-\norganized and extended the discussion part. -> see pp. 13-21.\nClarify a stepwise pathway for challenging Last-Glacial absence models: why the\nconsensus held the interior to be unpopulated in hyper-arid periods (MIS 4/3/2), how\nstratigraphic scarcity and regional climate interpretations shaped that view, and how\nyour 60–16 ka chronology reframes it via multi-pulses of terminal-Pleistocene\noccupation with short-lived hydrological conditions.\n-> We appreciate the suggestion of an alternative approach to the discussion. We followed\nthis recommendation and changed the entire discussion according to the reviewer’s\nsuggestions. See discussion on pages 13-21 in the revised manuscript.\nOnce the core findings are sharpened, the compilation of dated archaeological sites\nshould enable revisions to dispersal routes and late-Pleistocene settlement dynamics,\nwhich could be delineated further in both text and map. For regional comparison with\n“northern corridor” frameworks, a similar work of OSL-based MIS 5 Levant wetland\ncorridors by Abbas et al. (2023, Human dispersals out of Africa via the Levant, Science\nAdvances) would be helpful.\n-> We agree with reviewer 1 that visualization of conclusions would improve communication\nof our results. We have created a new figure (Fig. 10, page 17) to visualize the main\nconclusions regarding potential spatial connectivity of populations settling in SE Arabia\nduring the last glacial period.\nMake the cross-disciplinary bridge explicit by showing how the Buhais sequence serves\nas an archaeological anchor for evaluating the hypothesized Basal Eurasian population;\ntemper claims where evidence is indirect.\n-> We considered this suggestion and have extended the respective paragraph on pages 20-21\nas follows: “Our results demonstrate that one of the last pre-50 ka populations in SW Asia\ncan be found in SE Arabia at Buhais Rockshelter. Presented chronological and cultural\nrecords form an empirical basis that provides a first anchor point for further cross-\ndisciplinary research into deciphering the Basal Eurasian population and human’s last\nglacial history in SW Asia.”\nA few missing references with OSL ages of Arabian water-lain sediments in the last\nglacial:\n1.Steffen Mischke et al., 2021. A Late Pleistocene Wetland Setting in the Arid Jurf ed\nDarawish Region in Central Jordan. Frontiers in Earth Sciences. doi:\n10.3389/feart.2021.722435\n2.Bety S. Al-Saqarat, et al., 2020. A wetland oasis at Wadi Gharandal spanning 125–70 ka\non the human migration trail in southern Jordan. Quaternary Research,\nhttps://doi.org/10.1017/qua.2020.82\n3.Abbas M et al., 2023. Human dispersals out of Africa via the Levant. Science\nAdvances, https://www.science.org/doi/10.1126/sciadv.adi6838\nThanks for these suggestions, we have added all of them.\nReviewer #2 (Remarks to the Author):\nThis manuscript reports new information from the Buhais Rockshelter in the United Arab\nEmirates. While the work reported is scientifically robust and has the potential to be\nsignificant, it comes across largely as a site report and it does not contribute a\nsubstantive, novel, argument or testing of hypotheses. For instance, take the title,\n‘Evidence from Buhais Rockshelter reveals human settlement in Arabia between 60,000\nand 16,000 years ago’. Given that several sites are already known in this time period in\nArabia (e.g. SD-1, Matafah), what is fundamentally novel about the new findings? The\nmost important part of the study is perhaps the discovery of Upper Paleolithic material –\nyet the authors say they are working on a separate paper about this (401), so not much\ninformation is given.\n-> We thank reviewer 2 for pointing this out, which gives us the opportunity for clarification.\nThe intention of this paper is the presentation of new findings from SE Arabia, which we\nbelieve have multiple important implications that are of interest for a wider readership. We\ndo not agree that three sites in Arabia (2 for the 60-ka window, 1 for the 35-ka and none for\nthe 16-ka window) can be excepted as being representative for 44,000 years of history in an\narea of about 3 Mio km². The two sites for the 60-ka window for example are located about\n1,400 km apart. While the southern one (SD-1) indeed provides substantial data (21m²\nexcavated area, 9 OSL dates, 5488 lithic artifacts), the northern one (ALM 3) provides much\nless extensive information (ca. 2m² excavated area, 2 OSL dates, 103 lithic artifacts from\nstratified context). The one site mentioned for the 35-ka window (Matafah) is a 3 m² test\nexcavation with 89 lithics where the original excavator claims that they have too few finds to\ncharacterize the lithic tradition. Moreover, all these sites represent occupation events from\njust one time slice. In contrast, our record now provides diachronic information from one\nlocality for the first time. This is currently exceptional in Arabia considering the period 60-12\nka and allows conclusions about local continuity or discontinuity in the settlement of a region,\nwhich also have inter-regional implications when compared with available records.\nWe added information about the extent of excavation and finds from Matafah and extended\nthe discussion to make it clearer why our data provides substantially new insights into Arbian\nlast glacial history. -> see p. 19 and discussion pp. 13-21.\nRegarding the comment on the UP material, we removed this phrase and added more data to\nprovide a more comprehensive insight into the recovered UP material. This is in line with a\nsuggestion by reviewer 3. Please see SI.\nCare is also needed with strawman arguments, namely they claim to “contradict the\nprevailing view of human absence in Arabia at the end of the Pleistocene”. The reference\ngiven for this is a paper about a speleothem record from Yemen. That paper argues\nwet periods facilitated dispersals into Arabia, but it is a strawman argument to claim that\nthis study in particular, and the ‘general view’ more broadly, is that there were no\nhumans in Arabia at the end of the Pleistocene. The work of Rose, Hilbert etc has long\nargued for a terminal Pleistocene human presence in southeast Arabia.\n-> We agree with the reviewer’s point that there are previous arguments for terminal\nPleistocene occupation of southern Arabia. These, however, consider, to our knowledge,\nmainly the latest part of the Pleistocene (~12 ka). We have re-written this part and added\nmore references that argue for scarce if not lack of occupation. We write now on page 14:\n“This in addition to scarce archaeological records from this period, often leads to the\nassumption of a largely uninhabitable Arabian Peninsula between approximately 60 ka and\n16 ka2,27,28.”\nSo while the study reports important findings, it does not seem like these are presented\nin a particular useful way, it is more like a site report with some vague indications of how\nthe findings relate to things like adaptation to arid conditions and ‘distinctive patterns of\nsettlement dynamics’ (page 3). Fundamentally, the story is seemingly one of repeated\nmigrations into the area in association with wet periods. The authors argue against Late\nPleistocene population continuity in Arabia. Instead, it looks like they have identified\npulses of hominin dispersal into Arabia, largely correlating with those already known\n(e.g. SD-1 ca 60 ka, Matafah ca 33 ka). They are also present a somewhat contradictory\nargument by attacking the point that dispersals into Arabia correlate with wet phases, by\nsaying their studies show the evidence of people in southern Arabia “during the\npresumably arid last glacial period”, but directly contradict themselves by finding that\nactually the periods of occupation correlate with “repeated reactivation of freshwater\nsprings and hydrological systems”. What their findings suggest is that the European-\nderived glacial-interglacial dichotomy may not be the most useful framework for low\nlatitude palaeohydrological change – as indeed many papers have argued in recent\nyears. They themselves point out how actually the regional sequence of SE Arabia\nsuggests human presence in association with Monsoon Index Peaks, when rainfall\nincreased in the area.\n-> We thank the reviewer for considering our results important. To further strengthen our\ncommunication, we re-organized and extended the discussion to make implications of our\nfindings better understandable. Please see discussion pp. 13-21.\nRegarding potential contradictory claims about occupation in SE Arabia during the\nsupposedly arid phase of the last glacial period, we agree with the reviewer that this claim\ncan be misunderstandable and is based on a simplified view. To take account of the obvious\ncomplexity of the problem, we added available information from both climate models and\nlocal records to explain the background in greater detail. We removed the phrase “supposedly\nhyper-arid conditions” -> see abstract, p. 1 and discussion pp.13-14.\nThe ‘nuts and bolts’ of the paper are good, such as the figures and the general\ndescriptions of the deposits, their associated archaeological assemblages, and\nluminescence age estimates are all clearly presented and logical. The problem is the\nlack of orientation of the study to the key research themes in the region.\n-> We are pleased to note that the reviewer appreciates our goal of basing the presentation of\nour results on solid archaeological, chronological and palaeoenvironmental field work data.\nWe used all reviewer comments to work extensively on the presentation of the implications of\nour findings and re-organized and extended the discussion. We believe that the new discussion\nnow provides a better orientation of our study to key research themes in Arabia -> please see\nthe discussion part pp. 13-21.\nReviewer #3 (Remarks to the Author):\nThe role of the Arabian Peninsula in the expansion of anatomically modern humans is a\nhotly debated topic in archaeological and palaeo-anthropological research. The\n“Southern dispersal route” is suggested by genetic evidence, but sound archaeological\nevidence is missing up to now. Therefore, any data from this region and this period of\ntime is most welcome. Especially the absence of stratified deposits, covering the\ntransition from Middle Palaeolithic to Upper Palaeolithic stone artefact traditions during\nthe Late Pleistocene made any conclusions about this important step in human history\nimpossible. Therefore, Buhais Rockshelter is a key-site with supra-regional relevance.\nThe presented results are of utmost interest for the scientific community and an\nappropriate publication absolutely desirable. This leads me to my main poiant of\ncriticism. In my opinion, the archaeological data on which these interpretations are\nbased, are not presented in an adequate manner. With the exception of the total number\nof lithics of each archaeological horizon (AH) no numeric values are specified in the\nmain text. Even in the Supporting Online Material, except for Fig. S2 and Table S1 no\nfurther information about the stone artefact assemblages is given. Table S1: Basic\ncharacteristics of lithic assemblages from Buhais Rockshelter, only shows values for the\nblank production. Some tables with metrical data and amount of tool-types, platform\ntypes etc. would be helpful and are in my opinion essential. The reader has to believe the\ndescription of the assemblages. But what does it mean that “Evidence for classic\nLevallois reduction systems are notably scarce in AH II”? Consequently, the results are\nnot transparent and it is also not possible to compare the assemblages with\nassemblages from other sites.\n-> We appreciate that reviewer 3 raised this point. This gives us the opportunity to add more\ndetailed archaeological data. We fully agree that the requested data is of importance for\nunderstanding the different material cultures at the site and are more than happy to add more\nspecialized data for the expert part of the readership of Nature Communications.\nImportant results of the paper (and absolutely worth publishing) are:\n- the indication of a local Middle Palaeolithic tradition during times of high aridity is an\nimportant research progress.\n- evidence of human presence and inhabitable environments in SE Arabia during the last\nglacial period.\n- indications of a LMP population replacement.\nHowever, results and conclusions have to be verifiable and this demands a presentation\nof data. This has been done for the dating- and the palaeo-environmental section of the\npaper but is missing for the archaeological part. It should be easy to add this information\n(for example some tables in the SOM), but it is a requirement for publication.\n-> We follow this recommendation and have added figures 3-7 and table 2 to the\nSupplementary Information.\nApart from that, there are only some minor questions and comments to specific text\npassages:\np.3, l. 3: mMarine iIsotope sStage (MIS) 5\n-> done\np.6: “During the excavations, seven sediment layers were identified based on their\ncomposition and designated as Geological Horizons (GH) 1 to 3. GH1 was further\nsubdivided into four sublayers (a-d), each exhibiting slightly different characteristics\n(Figs. 4, S1).” This is a little bit confusing. Rewording might help (During the excavations,\nthree Geological Horizons (GH) were identified based on their composition and\ndesignated as GH 1 to 3. GH1 was further subdivided…….).\n-> done\nFigure 4. Is the naming of the Geological Horizons correct (GH1, GH1a, GH1b & GH1c)\nShouldn’t it be GH1a to GH1d?\n-> no, since GH 1d is just a local lens visible exclusively in the western profile, please see\nSupplementary Fig. 1.\np.8, l.4: Without reading the SOM, it is hard to understand the naming of AH Ia/I.\n-> thank you for pointing this out, we added a note after the first occurrence of AH Ia to make\nthe reader aware of additional information, we added “(see Supplementary Site Information\nfor details on the nomenclature)” after the first mentioning of the term AH Ia on page 7.\np.8: “All flake and blade types were produced by hard stone hammer percussion”. Why?\nWhat is the evidence for this?\n-> Hard stone hammer percussion is typically identified from morphological features of the\nflakes and blades such as pronounced bulbs of percussion and relatively thick striking\nplatforms. We have added this information to the text on page 7.\np.8: “Tool typologies include typical MP types such as notches and denticulates as well\nas sidescrapers, and short atypical endscrapers.” How are notches and denticulates\ndefined? What are the total numbers of tool types?\n-> We follow here the standard definition as for example provided by the “Handbook of\nPaleolithic Typology” (Debénath and Dibble, 1994). Notches are lithic artifacts with one\nnotch near the edge of the artifact while denticulates feature two and more notches often\ncreating toothed edges. We have added numerical information to the supplementary\ninformation.\np.10: “The tool assemblage comprises typical UP types such as endscrapers, burins and\ntruncations.” Numbers?\n-> We have added information on the typology to the supplementary information, which now\nalso includes more numerical information. Please see Supplementary table 2 and\nSupplementary fig. 3.\np.20: “Every quarter square was excavated to a depth of about 3 cm, which fills about\none 12 l bucket.” What is the smallest excavation unit? Quarter square x 3cm? One 12 l\nbucket? And why “about 3 cm” and “about one bucket”? Shouldn’t it be “exactly 3 cm &\nabout one bucket” or rather “about 3 cm & exactly one bucket”? Maybe, it is just my\nfallacy of thinking.\n-> the smallest unit is 25cm x 25cm x one 12l bucket, the 3cm are mentioned to give an\nimpression of the progress. Very often it is about 3 cm. The normal approach is that we aim at\nfilling one12l bucket in one round, but it is never exact, since we must take multiple aspects\ninto account when digging. First we follow the natural slope and thickness of the sediment\n(and we stop in case we reach a new layer), second we try to reduce the entire excavated area\nas one, which means there should be no steps to the neighboring ¼ squares. Third the amount\nof sediment excavated in one round is also related to the size of rock fragments that are part\nof the excavated sediments. Taken all this together will in reality not allow exact 12l to be\nexcavated all the time. This is why we used the wording as it is.\np.21: “Huweimi (Fig. 9) “. Fig. 9? Is this correct?\n-> thanks for spotting this, we changed the reference to figure 8. Now on page 22."}, {"round": 2, "reviewer_comments": {"reviewer_1": "I am satisfied with the revision, and reccommend publication.", "reviewer_2": "I think that the authors have addressed the review suggestions well and that the paper is ready to be published.", "reviewer_3": "I appreciate the careful reworking of the manuscript by the authors. My main concern had been the, in my opinion, inadequate presentation of the archaeological material. The presented data did not allow the reader to comprehend the interpretation of the material by the authors and, finally, also not their conclusion. This did not do justice to the significance of the site with is an important key-stratigraphy for the region.\nThe revised version fulfils my expectations in every way. For this reason, I can approve the publication of the manuscript without any objections.\nWith many thanks (to authors and editor) and best wishes"}, "author_response": ""}]

Decision letter