Reply to Blockley, Donahue & Pollard.

Reply to Blockley, Donahue & Pollard. We welcome Blockley et al.'s paper that raises the issue ofcalibration in the Late Glacial, although for reasons given below webelieve their conclusions are premature. We are also gratified grat��i��fy?tr.v. grat��i��fied, grat��i��fy��ing, grat��i��fies1. To please or satisfy: His achievement gratified his father.See Synonyms at please.2. that theyselected our paper from among several major books and papers on theperiod which have appeared since 1996 (Larsson 1996a; Otte 1997; Strauset al. 1996; Street & Terberger 1999; Tolan-Smith 1998). What thiswider sample of the relevant Palaeolithic literature demonstrates --about which Blockley et al. seem unaware -- is the degree ofinconsistency in current approaches to calibration. Some of the papersin the edited volumes by Larsson (1996b) and Straus et al. (1996)calibrate To adjust or bring into balance. Scanners, CRTs and similar peripherals may require periodic adjustment. Unlike digital devices, the electronic components within these analog devices may change from their original specification. See color calibration and tweak. , whilst others do not. Otte (1997) presents calibrated dateswhile Tolan-Smith (1998) prefers uncalibrated radiocarbon years for hisstudy of the British data. This hesitancy is not confined toarchaeologists, for the same is seen in geography. For example, at theEnglish Heritage conference on Science in Archaeology, Edwards (1998)does not calibrate his pollen curves, although in a standard textbooksuch as Lowe & Walker (1997) calibration can be found. This is in aperiod where good calibration curves are available and the author is aformer chair of the NERC NERC Natural Environment Research Council (UK)NERC North American Electric Reliability Corporation (Princeton, New Jersey, USA)NERC Northeast Recycling CouncilNERC National Environment Research Council Radiocarbon Accelerator Dating Service AdvisoryPanel. Consequently we agree with Street & Terberger (1999: 260),writing in ANTIQUITY, that in the Late Glacial: Until there is consensus for a common calibration system, thepresentation of the `raw dates' avoids confusion and even theuncalibrated radiocarbon dates provide convincing evidence forcontinuity or hiatus of settlement in different regions of Europe Europe is often divided into regions due to geographical, cultural or historical criteria. Some common divisions are as follows. Directional divisionsGroupings by compass directions are the hardest to define in Europe, since (among other issues) the pure geographical criteria . Let us be clear what Blockley et al. are advocating, namely the useof the 1993 and 1998 marine curves for calibrating radiocarbondeterminations on terrestrial archaeological samples. It is important torealize just how problematic these curves currently are for uncriticalarchaeological use. The marine curves are based on paired U/Th and AMS AMS - Andrew Message System [.sup.14]C determinations of corals. Although it is assumed that U/Thages conform to a calendrical timescale, it is not proven. One only needlook at the early history of the [.sup.14]C method to see how we oncethought [.sup.14]C was an absolute method and it was only later realizedthat uncalibrated [.sup.14]C ages were not calendar years. There is alsothe question whether corals are closed-systems, for if loss or exchangeof Th has occurred the data will be invalid. However, the over-ridingproblem for this period is the varying marine reservoir effect.Fluctuations in the amount of old carbon incorporated into the oceansduring deglaciation de��gla��ci��a��tion?n.The uncovering of glaciated land because of melting or sublimation of the glacier.deglaciation?The uncovering of land that was previously covered by a glacier. means that the 400-year present-day offset cannot beassumed. Although we acknowledge that the marine curves are useful forindicating the long-term age offset between the [.sup.14]C timescale andcalendrical time, the smoothed nature of the ocean-derived data and thevariable marine reservoir effect means they should only be used withcaution. It is because the calibration data are so heavily smoothed thatBlockley et al. dispute our notion of a northward movement of peoples.We acknowledge that calibration should be a goal but to have simplyadopted the marine data as it was available in 1997 seemed to uspremature. The subsequent publication, in late 1998, of a new integrateddecadel calibration curve (Stuiver et al. 1998) partly answers theseconcerns, but the precision is still poor in the Late Glacial oncebeyond the limit of the German Pine dataset (i.e. for ages [is greaterthan]11,871 calendar years BP). In essence, Late Glacial Palaeolithic archaeology is undergoing theinterest that surrounded the first calibration curve 25 years ago thatgave us Wessex without Mycenae (Renfrew 1968). We need to ensure that,as calibration is extended, it is extended for a good archaeologicalreason. Clearly the issue of re-colonization and settlement pattern isfertile ground for wanting the precision which calibration offers. Ourapproach to colonization as a process rather than an event provides justsuch a framework for the assessment of accuracy and the impetus forfurther precision. The rather weak correlation that Blockley et al.(FIGURE 6b) propose between climatic amelioration in the GISP GISP Global Invasive Species ProgrammeGISP Gonococcal Isolate Surveillance ProjectGISP Greenland Ice Sheet ProjectGISP Geographic Information Systems ProfessionalGISP Group Independent Study ProjectGISP Global Information Society Project 2 curve andMagdalenian settlement is precisely the sort of correlation which nowneeds to be investigated rather than asserted. Since their model appearsto be based on a simplistic sim��plism?n.The tendency to oversimplify an issue or a problem by ignoring complexities or complications.[French simplisme, from simple, simple, from Old French; see simple environmental determinism, it is up to themto explain why change in temperature was the critical factor. Simplyascribing the whole process just to environmental changes is not thefinal goal, for one has to think in terms of human response. Moreover,since they prefer a settlement system rather than a population movement,why do they curtail their study with our dates? Why do they not continuethe analysis (the dates are widely published in the books cited above)to see how the later fluctuations in the GISP2 curve (FIGURE 6b)affected, or did not affect, the radiocarbon evidence? If they prefer amodel whereby change is solely people re-organizing their settlementsystems, then they need to select an appropriate set of data adequatelyto test their environmental assumptions. This they have not done. Usingour data we tested a model of re-colonization where we suggested thatsettlement pattern had to be understood in the context of a process ofpopulation dispersal. [FIGURE 6b ILLUSTRATION OMITTED] The two-stage model we advanced is supported, albeit at longertime-scales, by Tolan-Smith's (1998) study of the re-settlement ofthe British Isles, Bracco's (1996) investigation of the MassifCentral and Larsson's (1996a) and Bang-Andersen's (1996)studies of southern Scandinavia. All of these studies use archaeologicaldata in conjunction with radiocarbon data to discern significantpatterning. The logical conclusion of Blockley et al.'s statisticalapproach is to lop LOP - A language based on first-order logic.["SETHEO - A High-Perormance Theorem Prover for First-Order Logic", Reinhold Letz et al, J Automated Reasoning 8(2):183-212 (1992)]. the tails off the distributions that would clearlymake archaeological nonsense, and we are pleased to see that they didnot. However, we are concerned that they seem unaware of the nature ofarchaeology when they criticize an approach that treats the earliestdates as significant. In all periods, but especially the Palaeolithic,new data can bring about major revisions of how we understand ourpatterns. They are criticizing us for what we cannot provide -- arepresentative assessment of the populations to be sampled before wehave sampled them. Taphonomic concerns dictate the availability of theright sort of sample, hence the bias towards caves. Carried to itsextreme they would be counselling an end to archaeological fieldwork andthe re-analysis of data because we will never he in a position toprovide what they require. We prefer the approach which has produced,since our paper, new data from Paviland (Aldhouse-Green & Pettitt1998) and the Rhineland (Street & Terberger 1999: figure 4) wheredates displayed as data clearly indicate a tiny presence during theglacial maximum followed by a major demographic expansion in theMagdalenian. Such studies also easily refute Barton's (1997: 117)claims of `over-interpretation'. The expansion now needs to becompared with the genetic evidence, which independently suggests that itwas this demographic process which established the genetic pattern ofEuropeans rather than a later dispersal of farmers from the Near East(Richards et al. 1996). We concede that there is obviously a great needfor more dates and an honest assessment from the statisticians of thelevels of accuracy that may be achieved. Ideally we would like toinvestigate the process at the interval of a human generation.Calibration should be seen as one step towards an integrated approach tosuch a major research frontier. References ALDHOUSE-GREEN, S.H.R. & P. PETTITT. 1998. Paviland Cave:contextualizing the `Red Lady', Antiquity 72: 756-72. BANG-ANDERSEN, S. 1996. The colonisation of Southwest Norway, anecological approach, in Larsson (ed.): 219-34. BARTON, R.N.E, 1997. Stone Age Britain. London: Batsford. BRACCO, J.-P. 1996. Du site au territoire: l'occupation du soldans les hautes vallees de la Loire et de l'Allier au paleolithiquesuperieur (Massif Central), Gallia Prehistoire 38: 13-67. EDWARDS, K.J. 1998, Detection of human impact on the naturalenvironment: palynological views, in J. Bayley (ed.), Science inarchaeology, an agenda for the future: 69-88. London: English Heritage. LARSSON, L. 1996a. The colonisation of south Sweden during thedeglaciation, in Larsson (ed.): 141-55. (Ed.). 1996b. The earliestsettlement of Scandinavia and its relationship with neighbouring areas.Stockholm: Almquist & Wiksell International. Acta ArchaeologicaLundensia 24. LOWE, J.J. & M.J.C. WALKER. 1997. Reconstructing Quaternaryenvironments. Harlow: Longman. OTTE, M. 1997. Paleolithique final du Nord-Ouest, migrations etsaisons, in J.-P. Fagnart & A. Thavenin (ed.), Le Tardiglaciare enEurope du Nord-Ouest: 353-66. Paris: CTHS CTHS Cherrybrook Technology High School (Sydney, Australia). RENFREW, C. 1968. Wessex without Mycenae, Annual of the BritishSchool of Archaeology at Athens 63: 277-85. RICHARDS, M., H. CORTE-REAL, P. FORSTER, V. MACAULAY, H.WILKINSON-HERBOTS, A. DEMAINE, S. PAPIHA, R. HEDGES, H.-J. BANDELT &B. SYKES. 1996. Palaeolithic and Neolithic lineages in the Europeanmitochondrial mitochondrialpertaining to mitochondria.mitochondrial RNAsa unique set of tRNAs, mRNAs, rRNAs, transcribed from mitochondrial DNA by a mitochondrial-specific RNA polymerase, that account for about 4% of the total cell RNA that gene pool, American Journal of Human Genetics 59: 185-203. STRAUS, L.G., B.V. ERIKSEN, J.M. ERLANDSON & D.R. YESNER (ed.).1996. Humans at the end of the ice age: the archaeology of thePleistocene-Holocene transition. New York (NY): Plenum. STREET, M. & T. TERBERGER. 1999, The last Pleniglacial and thehuman settlement of Central Europe: new information from the Rhinelandsite Wiesbaden-Igstadt, Antiquity 73: 259-72. STUIVER, M., P.J. REIMER, E. BARD, J.W. BECK, G.S. BURR, K.A.HUGHEN, B. KROMER, G. MCCGRMAC, J. VAN DER DER - Distinguished Encoding Rules PLICHT & M. SPURK. 1998.INTCAL98 Radiocarbon Age Calibration, 24,000-0 cal BP, Radiocarbon40(3): 1041-84. TOLAN-SMITH, C. 1998. Radiocarbon chronology and the Late Glacialand early Postglacial post��gla��cial?adj.Relating to or occurring during the time following a glacial period.postglacial?Relating to or occurring during the time following a glacial period.Adj. 1. resettlement Re`set´tle`mentn. 1. Act of settling again, or state of being settled again; as, the resettlementof lees s>.The resettlementof my discomposed soul.- Norris. of the British Isles, QuaternaryInternational 49/50: 21-7. Housley, Department of Archaeology, University of Glasgow The University of Glasgow (Scottish Gaelic: Oilthigh Ghlaschu, Latin: Universitas Glasguensis) was founded in 1451, in Glasgow, Scotland. , GregoryBuilding, Lilybank Gardens, Glasgow G12 8QQ, Scotland.r.housley@archaeology.arts.gla.ac.uk Gamble, Department of Archaeology,University of Southampton In the most recent RAE assessment (2001), it has the only engineering faculty in the country to receive the highest rating (5*) across all disciplines.[3] According to The Times Higher Education Supplement , Southampton SO17 1BJ, England.C.S.Gamble@soton.ac.uk Pettitt, Research Laboratory for Archaeology& the History of Art, 6 Keble Road, Oxford, OX1 3QJ, England.paul.pettitt@archaeology-research.oxford.ac.uk