Climatic oscillation as a factor in the prehistory of amazonia

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Climatic oscillation as a factor in the prehistory of amazonia

  1. 1. Society for American ArchaeologyClimatic Oscillation as a Factor in the Prehistory of AmazoniaAuthor(s): Betty J. MeggersSource: American Antiquity, Vol. 44, No. 2 (Apr., 1979), pp. 252-266Published by: Society for American ArchaeologyStable URL: http://www.jstor.org/stable/279075 .Accessed: 25/04/2011 23:46Your use of the JSTOR archive indicates your acceptance of JSTORs Terms and Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp. JSTORs Terms and Conditions of Use provides, in part, that unlessyou have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and youmay use content in the JSTOR archive only for your personal, non-commercial use.Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at .http://www.jstor.org/action/showPublisher?publisherCode=sam. .Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printedpage of such transmission.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact support@jstor.org.Society for American Archaeology is collaborating with JSTOR to digitize, preserve and extend access toAmerican Antiquity.http://www.jstor.org
  2. 2. CLIMATICOSCILLATIONAS A FACTORIN THEPREHISTORYOF AMAZONIABetty J.MeggersThe existence of climatic oscillations during the Quaternary in the Neotropics was inferred from thedistributions and diversities of the modern flora and fauna. Recent data on soils, geomorphology, palynology,and paleoclimatology confirm the existence of periods of aridity and permit more accurate definition of theirdurations and impacts. A review of linguistic and archaeological evidence reveals patterns similar to those ex-hibited by a wide range of biological phenomena. The significance attached to these similarities depends on thetheoretical paradigm by which they are judged.WHITTENHAS PAID ME A COMPLIMENTin labeling my use of the refugia model to interpretcultural distributions "premature." According to my unabridged dictionary, this means theanalysis is ahead of its time, which implies it will become acceptable in the future. I judge fromthe tone of the "comment," however, that he is employing a more colloquial meaning, namely, thatthe effort is "half-baked." These conflicting definitions symbolize the fundamental difference be-tween Whittens concept of scientific procedures and mine, which is masked by his contentionthat I have played fast and loose with paleoclimatological and linguistic evidence.Since 1969, when Haffer published his paper suggesting that the modern distribution of birds inlowland South America could most economically be explained as a consequence of cyclical frag-mentation and coalescence of the rain forest, tropical biologists have applied this model suc-cessfully to a great variety of flora and fauna. Detailed maps of vegetation and soils, compiled toassess the potential of the Brazilian Amazon region for agricultural development, provide addi-tional support. Although the picture is by no means complete, its general outline is far clearer nowthan it was when I first attempted to evaluate its relevance for interpreting prehistoric humanevents.Space does not permit discussing all Whittens criticisms and misstatements of my position, butmost of these should be obvious to anyone who rereads my articles. I will confine myself to threebasic issues: (1) the validity of the refugia model, (2) the relevance of the model for interpretinganthropological data, and (3) the difference between my conception of scientific method and thatheld by Whitten.THE VALIDITYOF THE MODELContrary to Whittens assertion, there is a considerable variety of direct evidence for climaticfluctuation in the Neotropics during the Quaternary (e.g., Haffer 1974:137-142). Establishing theexistence of oscillations is one problem; explaining them is another. It is not surprising thatweather patterns during the decade between 1961 and 1970 disagree with those implied by therefugia model. Reconstructing climatic history requires far more sophisticated kinds of data andmethods of analysis than those employed by Whitten. Specialists from 18 institutions have beencollaborating since 1971 on models that incorporate detailed information on sea level, extent ofpermanent ice, reflectivity of land surfaces, and temperature of the surface of the ocean, the lastbeing inferred from analysis of hundreds of cores in sea-floor sediments (CLIMAP ProjectMembers 1976; Gates 1976). A simulation of global conditions during July, 18,000 B.P., indicatesthat "compared with the simulation for present July climate, the ice age is substantially coolerand drier over the unglaciated continental areas" (Gates 1976:1143). Geological and paleo-climatological investigations by Damuth and Fairbridge (1970), Bigarella (1971), and others alsoBetty J. Meggers, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560252
  3. 3. CLIMATICOSCILLATIONINAMAZONIANPREHISTORYindicate that semiarid conditions prevailed in South America during glacial periods and humidconditions during interglacials. Systematic changes in winds and offshore currents have beenproposed to account for these fluctuations (AbSaber 1977:6). AbSaber (1977) has integratedclimatic, geomorphological, and botanical data to reconstruct the natural morphoclimatic do-mains between about 18,000 and 13,000 B.P. His map shows patches of forest closely similar insize and location to the refugia hypothesized by biogeographers (Figure 1). The processes con-ducive to biological differentiation under climatic stress and some of the variables likely to affecttheir expression have been summarized by Brown (1977:77-78, 98-102).The existence of a significant alteration in the vegetation of lowland South America betweenabout 18,000 and 13,000 B.P. seems established. The sizes, locations, compositions, and durationsof the rain-forest refuges await refinement. The duration of the climax, the nature of thenonrefuge vegetation, and the characteristics and durations of the periods of transition also re-main uncertain. Rates and intensities undoubtedly varied in different times and places, com-plicating reconstruction of this episode and assessment of its local impact. Evidence for similarclimatic changes in tropical Africa and Asia is compatible with the interpretation of these oscilla-tions as expressions of global processes just beginning to be understood (Laurent 1973; Liv-ingstone 1975).What about reduction in the extent of humid forest during the Holocene? I did not invent thisepisode to explain linguistic diversity, as Whitten supposes; had this been my procedure, I wouldhave selected dates more consistent with those provided by glottochronology. I examined all thepublications available to me for data on climatic change, compared the estimated durations ofperiods of aridity, and chose as a general approximation an interval between + 4000 and = 2000B.P. Recent data of several types strengthen the case for climatic fluctuations during the past fewmillennia.Figure 1. Refugia reconstructed from the modern distributions of plants (hachure) and butterflies(outline). Biogeographical evidence for fragmentation of the humid forest several times during the Quater-nary is supported by differences in soil types and by paleoclimatology (after Prance 1973:Figure 24 andBrown et al. 1974:Figure 3).Meggers] 253
  4. 4. AMERICAN ANTIQUITYThe changes in sea level along the coast of Brazil reconstructed by Fairbridge (1976) and theclimatic shifts during the past five millennia inferred by several investigators are compared inFigure 2. Whitten contends that the duration of the cool and dry episodes postulated by Fair-bridge "in no way agrees" with the dates I employed. It seems to me that Fairbridges Periods Vand VI, extending from 3400 to 2000 B.P., agree very well with my 4000 to 2000B.P. estimate.Period III, between 4800 and 4100 B.P, is also considered cool and dry. Thusrecool and dry condi-tions prevailed between 4800 and 2000 B.P., in the opinion of Fairbridge, except during Period IV,which lasted only about 700 years. Bigarella (1971:15) postulates intermittent dry spells between4500 and 2500 B.P. in southern Brazil. Haffer (1974:142) places the last severe arid phase be-tween 4000 and 2500 B.P. Prance (1978:Table 2) assigns an earlier inception to the Holocene dryperiod on the basis of evidence from as far north as Mexico, but his terminal date of 2000 B.P.agrees with the other estimates. His revised reconstruction of the sizes and locations of therefugia differs from the earlier version (see Figure 1) principally in showing gallery forest alongthe lower Tapajos, Madeira, and Purus (Prance 1978:Figure 9).Dates associated with marine deposits exposed on the coast of Pernambuco depart slightlyfrom the pattern of sea-level change presented by Fairbridge. Here Van Andel and Laborel (1964)observed a rise to 2.2 m about 2800 B.P. (Figure 2). Abundant evidence for localized oscillations insea level and climate has accumulated for the Caribbean area; not only did drastic changes occurseveral times in the vegetation, but communities of plants without modern analogs prevailed dur-ing some of the episodes (Carbone 1978).Existence of a recent corridor of savanna or similar open vegetation between the island ofYEARS B.P. SEA LEVEL ARID EPISODES(I) (2) (3) (4) (5) (6)o -_-10005000 ---<, ///2000 -iv7000Vy+22 +I 0 --250006000 /7000+2 +1 0 -I -2Figure 2. Changes in sea level and shifts in climate during the Holocene according to several author-ities. Although details differ, there is general agreement that conditions were drier and cooler between? 4000 and ? 2000 B.P. Sources are (1) Fairbridge 1976:Figure 3; (2) Van Andel and Laborel 1964; (3) Fair-bridge 1976; (4) Haffer 1974:142; (5) Prance 1978; (6) Bigarella 1971:15.[Vol. 44, No. 2,1979254
  5. 5. CLIMATICOSCILLATIONINAMAZONIANPREHISTORYMarajoandeastern Brazilis impliedby the relatedherpetofaunainthese regions.Marajohas anelevation onlyabout 2 m above present sea level and consequentlywouldhave been submergedwhenever the water rose above that height.Data fromthe coast of Pernambuco(citedabove)in-dicate that such a submergence prevailed from before 3600 to at least 2800 B.P. Since theherpetofauna could not have migrated through forest, its dispersal must have taken place afterexposure of the surface of the island and before reforestation of the mainland.Prance (1978:213-214) has pointed out that the enclaves of savanna in the Amazonian forestare refugia for savanna species. Thepresence of the same species in mostof these relict savan-nas "is best explained by a former more continuous distribution. The Amazon savannas are notparticularlyrichin endemicplant species which also indicatesthat theywere joinedtogether[inthe recent past]" (1978:214, Figure 11; cf. Eden 1974; Descamps et al. 1978).The low proportion of endemic families and genera among Amazonian plants is also"characteristicof a floraof relativelyrecentorigin"(Prance1978:216-221).Ofa totalof 161,onlythree small families are restricted to Amazonia. The majority of the genera are also distributedoutside the region. By contrast, most of the species are endemic and reflect adaptation to the re-cent habitats created by present environmental conditions.Although more examples could be cited, these illustrate the kinds of evidence implying that therain forest experienced climatic stress between + 4000 and ? 2000 B.P. sufficiently intense toaffect the forest biota. A better correlation between the chronologies from different parts of thelowlands would be surprising, considering the vastness of the region, the few carbon-14 deter-minations, the differential specificity of the clues (marine formations versus relict populations),and the probability of local variations in timing and intensity of drought. Reconstructions ofHolocene conditions in North America and the Caribbean, where much more work has been done,are in keeping with the pattern described for Amazonia. Given the worldwide evidence for oscilla-tions in climate, the absence rather than the presence of similar episodes in the Neotropicallowlands would require explanation.Whittens remarks to the contrary notwithstanding, neither I nor any other archaeologist mak-ing use of paleoenvironmental data has the obligation to account for them. Although a specialiston paleo-Indian cannot explain the genesis of glaciers or their withdrawal, this does not exempthim from using reconstructions of Pleistocene conditions to interpret the archaeological record.On the contrary, failure to take them into account would invalidate the results. Anthropologistslack the expertise for discerning the causes of climatic change and have no need to develop it. Ourtask is to establish whether such changes had an impact on the people who left the archaeologicalrecord.RELEVANCEOF THE MODELFOR INTERPRETINGANTHROPOLOGICALDATAThe refugia model offers an explanation for the distributions and diversities of many biologicalphenomena. The same general patterns have been observed among plants and animals, both in-vertebrates and vertebrates. Given this wide applicability, I considered it of interest to seewhether the linguistic and archaeological data exhibited similar kinds of general patterns.I did not begin with the "assumption of the breakup of the Ge-Pano-Carib language group at ca.10,000 B.P."; I began with a date corresponding to the conclusion of the arid period (indicatingrestoration of the forest) at the end of the Pleistocene and looked for some kind of linguistic cor-relation. Nor did I assume "the linguistic and temporal priority of a refugium in the southeasternpart of Amazonia"; I assumed the Brazilian highlands were unforested then as now. Whittensassertion that a constant rate of change is "the fundamental assumption of glottochronology" isrefuted by a plethora of articles discussing the variables conflicting with this assumption (e.g.,Lees 1953; Chretien 1962; Dyen 1971; Hymes 1960; Gudschinsky 1955; Bergsland and Vogt 1962;Swadesh 1952, 1955a, 1955b). Although Whitten rejects the linguistic reconstructions I used infavor of an unpublished analysis by Stark (1977) that "describes a different pattern of time anddispersal," he indicates that her estimated date for the divergence of Proto-Arawakan fromProto-Tupi-Guaranian is similar to the one suggested by Noble (1965) and Rodrigues (1955) andthat her center of dispersal is in the same general part of the lowlands. These results seem to meMeggers] 255
  6. 6. AMERICANANTIQUITYremarkably congruent, given the uncertainties of inferring linguistic relationships and identifyingcenters of dispersal (Diebold 1960; Dyen 1956).The paucity of archaeological evidence for reconstructing the prehistory of the humid lowlandsmakes language a primary source of information. If associations could be established betweenlanguage families and ceramic traditions or between stages of linguistic diversification andperiods of environmental change, these correlations not only should provide a basis for tracingmovements of populations but also might permit selecting a more accurate rate for applying glot-tochronology to unwritten languages. Until recentecly,these possibilities could not be assessed inlowland South America because neither the paleoecology nor the archaeological sequences weresufficiently well known. We now have enough data to begin searching for correlations, keeping inmind that all results must be viewed as highly tentative.To compare patterns of differentiation in Tupi-Guaranian and Arawakan-the two largest andmost widespread linguistic stocks-I tabulated the percentages of shared cognates provided byRodrigues (1955) and Noble (1965). In both stocks, these range between 7% and 45%, except forseven pairs of Tupi-Guaranian languages sharing 60% or more cognates (Figure 3). The progres-sion toward diversification appears intermittent in Arawakan and continuous in Tupi-Guaranian,but this may reflect the availability of nearly twice the number of cases in the latter sample (101versus 51 for Arawakan). Thirty-six percent of the Arawakan pairs share between 33% and 45%cognates, in contrast to 6% of the Tupi-Guaranian pairs. The range between 7% and 24% cog-nates contains 45% of the Arawakan and 73% of the Tupi-Guaranian pairs. Note that cognatecounts between 7% and 28% correspond to differentiation of these stocks into families, those be-tween 29% and 45% to differentiation of the families into languages, and those above 60% to dif-ferentiation of the language into dialects.What signifi c an be attached to these data? Among plants and animals, differentiation isfacilitated by partial or complete isolation of populations of the same species. Linguistic diver-sification is also promoted by diminution or cessation of communication between groups ofspeakers. The question is: does change occur at a sufficiently consistent rate to serve as a timescale? The answer is still ambiguous. The rate usually employed is 80.5% retention of cognatesper millennium, which is the mean obtained from comparing 13 written languages (Lees 1953). Itserves as a standard for conversion, much like the value of 5,570 years for the half-life ofcarbon-14 adopted by archaeologists; but if it is inaccurate, the consequences can be significant.The time depths calculated using rates of 70%, 75%, and 80.5% retention per millennium differsubstantially (Figure 3). Sharing of 20% cognates may imply times of separation between 2256and 5300 B.P. Sharing of 40% cognates may indicate between 1,284 and 3,100 years of separa-tion. Although this variability appears excessive, it is not much greater than the elasticity ofcarbon-14 determinations (Stuckenrath 1977). We do not reject carbon-14 dating because it is notprecise; we try to identify and minimize the sources of error. Glottochronology has demonstratedenough potential to warrant similar efforts to understand the variables affecting rates oflinguistic change (cf. Andreyev 1962).Environmental instability is not the only type of event conducive to biological or linguistic diver-sification, but when it occurs its impact is likely to be significant. If the period of aridity between?+ 4000 and ? 2000 B.P. affected the subsistence resources exploited by human populations, theywould have been forced to adapt to conditions of lower productivity. The demographic conse-quences (lowered density, increased mobility, migration, extinction) should be reflected in pat-terns of linguistic divergence. This hypothesis offers a basis for selecting the most appropriaterate among those in Figure 3. If the differentiation of the Arawakan and Tupi-Guaranian stocksinto families took place during the most recent arid episode, the range between 7% and ? 28%shared cognates should correspond to the millennia between ? 4000 and ? 2000 B.P. By thiscriterion, the 80.5% rate is too slow, but the 75% rate places separation of the families between? 4600 and ? 2100 B.P., differentiation of the languages within families between ? 2100 and? 1300 B.P., and differentiation of the dialects after ? 900 B.P.Archaeological evidence from the coast of Brazil can be used to evaluate this calibration.Historical documents and trade goods identify village sites occupied by speakers of Tupi-256 [Vol. 44, No. 2,1979
  7. 7. CLIMATICOSCILLATIONINAMAZONIANPREHISTORY>60FREQUENCIESOF COGNATEPAIRSARAWAKAN TUPI-GUARAN IANV/////145L4443424140I 3393837o 3635< 32L 31Q?3029a 28< 27eu 26250 2403 z232- 222: 21 ///o 209 /18o 17 71615z 14Li 13E- 12o IIe,1087TIME SCALE(YEARS B.P)CORRELATIONWITH ARID EPISODE716 888 10971119 1388 18411287 1593 21121472 1825 24201688 2093 27751943 2409 31962256 2797 37102659 3297 43733228 4002 53083728 4621 6129I I I I I I I I I I I I I I I I I I0 1 2 3 4 5 6 7 8 0 2 3 4 5 6 7 8 70% 75% 80.5% 75% 80.5%NUMBER OF CASES RATE OF RETENTION PER MILLENNIUMFigure 3. Progressive diversification of Arawakan and Tupi-Guaranian, as shown by the frequencies ofcognates shared by pairs of languages. The time depths calculated using rates of retention of 70%, 75%,and 80.5% per millennium differ considerably. If differentiation of the stocks into families occurred duringthe Holocene arid episode, the range from 7% to ? 29% cognates should correlate generally with theperiod from ? 4000 to ? 2000 B.P. The 75% rate fits better than the 80.5% rate, which is employed as astandard for glottochronology. (Cognate counts from Noble 1965 and Rodrigues 1955; time depths fromSpielman et al. 1974:Table 3 and Migliazza, personal communication.)Guaranian at the time of European contact. These sites have pottery with distinctive decoration,which has been traced backward through time and space. Hundreds of habitation sites have beenmapped, dozens of relative chronologies have been constructed, and more than 80 carbon-14dates have been obtained. These data indicate that speakers of Tupi-Guaranian reached thesouthern coast ? 1400 B.P. and spread northward (Figure 4). Since the other languages belongingto the same family are distributed along the south side of the lower Amazon (Figure 5), physicalseparation of the speakers must have occurred before this date. Again, the 75% rate providesbetter agreement than the 80.5% rate. These results must be viewed with extreme caution, butV)uUJ_1<Meggers] 257
  8. 8. AMERICANANTIQUITYDISPERSAL OF TUPI- GUARANIANSPEAKERSt 1400 B.P. ACCORDINGTO LATHRAPFigure 4. Conflicting reconstructions of the dispersal of Tupi-Guaranian. Lathrap has inferred a spreadout of the lower Amazon beginning ? 1400 B.P. Carbon-14 dates from numerous sites along the coast ofBrazil indicate, however, that pottery of the Tupiguarani tradition appeared in the south i 1400 B.P. andspread northward during subsequent centuries.the discovery of a possible correlation is encouraging and suggests that additional experiments ofthis kind would be worthwhile.Few linguists have been willing to venture reconstructions of ancient relationships. Swadesh isan outstanding exception (e.g., 1964), but his formulations apply mainly to North and CentralAmerica. The only comprehensive classification of South American languages is by Greenberg(1960; Steward and Faron 1959:22-23), who combined them into four "families," the largest andmost widespread of which are Andean-Equatorial and Ge-Pano-Carib. Arawakan and Tupi-Guaranian are assigned to the Equatorial division of Andean-Equatorial. Although some of thealignments have been questioned, it has not been established that his entire classification is in-valid. One means of assessing the validity of relationships not clearly discernible using linguisticmethods is by comparing the distributions of such generalized groupings with predictions basedon the refugia model.Ge-Pano-Carib languages are spoken over a large area southeast of Amazonia, in the Guianas,along the coast of Venezuela, and on the eastern margin of the Andes (Figure 6). The central low-lands are occupied by speakers of the Equatorial division of Andean-Equatorial. A biogeographerwould interpret this pattern as evidence for the intrusion of the Equatorial languages into the258 [Vol. 44, No. 2,1979
  9. 9. CLIMATICOSCILLATIONINAMAZONIANPREHISTORY /A1 ARAWAKAN. ....V TUPI:i TUPI-GUARANIANV^ /^N.tl, EJ1 CARIBAN4Xj<^ AMgAA~,7_REFUGIOSFLORESTADOS---LIMITE ATUALDEX1^~v-^PAj~ F~yPRECIPITA;AO ANUALa ^0-^ / DE 2000 MILIMETROSFigure 5. Correlationof speakers of Tupi-Guaranianand Arawakanlanguages with the portions ofAmazoniareceiving more than 2,000 mmannualrainfall. Caribanspeakers are concentratedin the driercorridorextendingfromthe coast of Venezuelaacrossthe Guianas.These habitatpreferences mayreflectancient adaptationsto forest and nonforest environments(after Meggers and Evans 1973:Figure3). Therefugia shown are those originallysuggested by Haffer, based on the distributionsof forest birds.lowlands, disrupting the formerly contiguous distribution of Ge-Pano-Carib. This inference is sup-ported by the habitats associated with recent representatives of these two generalized linguisticgroups. Ge-speakers dominate the arid uplands of eastern Brazil; Carib-speakers are concen-trated north of Amazonia and in a corridor across the Guianas, where rainfall is less than 2,000mm annually (Figure 5). Reduction of the humid forest between ? 18,000 and =4 13,000 B.P. wouldhave permitted hunter-gatherers adapted to open landscapes to spread over the lowlands. Theirrecent habitat preferences favor the hypothesis that these migrants were speakers of Proto-Ge-Pano-Carib. Similarly, coalescence of the forest would have allowed groups adapted to theseresources to spread out. The correlation between speakers of Equatorial languages and regionsreceiving more than 2,000 mm annual rainfall makes them logical candidates for this colonization.Other evidence compatible with this reconstruction comes from archaeology and from in-vestigations of genetic variation among Ge-speaking tribes. The latter have suggested the "verytentative interpretation" that these groups "are more representative of at least one of the[biological] stocks which originally entered South America than the frequencies of any otherdefined group of Indians" (Salzano et al. 1977:346). The presence of hunter-gatherers in Goias,Pernambuco, Minas Gerais, and Mato Grosso at least 10,000 B.P. has been established by car-bon-14 dates from numerous sites (Figure 6). Equally old (or older) deposits have been reportedfrom southern Brazil, Tierra del Fuego, Chile, Peru, Ecuador, Colombia, and Venezuela (Bryan1973:244). It has been suggested that these represent at least four cultural complexes, charac-Meggers] 259
  10. 10. AMERICANANTIQUITY10,750 t 300 (SI-2769)10,740 +85 (S1-311)10,400 i 130 (N-2348)lT. _~ LUU 212,770. 220 (SI- 801),,-mjl^^~~~10,985+100 (SI-2630)t /-^ ^^^^"^~~ 10,810 t 275 (SI - 2622)m GE- PANO-CARIBMII ANOEAN- EQUATORIAL:MACRO- CHICHANFigure 6. Possible correlation between linguistic distributions, archaeological evidence, and the refugiamodel. The geographic patterning of the languages assigned by Greenberg to the Ge-Pano-Carib andAndean-Equatorial groups suggests that representatives of the latter protophylum expanded eastward,displacing and separating speakers of the Ge-Pano-Carib protophylum. The association of present-dayspeakers of Equatorial languages with forest, and Ge- and Carib-speakers with drier, habitats (Figure 5), aswell as the apparent antiquity of the linguistic separation, favors the hypothesis that this displacement oc-curred when the humid forest coalesced at the end of the Pleistocene. The existence of hunter-gathererssouth of Amazonia by ? 11,000 B.P. has been established by carbon-14 dates from at least eight sites ineastern Brazil. These coincidences suggest that the people who left these archaeological remains may havebeen speakers of Proto-Ge languages. (Linguistic distributions after Steward and Faron 1959:23.)terized by different technologies and subsistence strategies and probably having different tem-poral and spatial distributions (MacNeish 1971, 1976). Since the technologies are distinct, thepopulations are likely to have had different antecedents; it is also reasonable to infer that theymay have spoken different languages.Perhaps these are all coincidences, but we have too few clues for reconstructing the distantpast to dismiss patterns compatible with biogeographical principles before giving them carefulconsideration. Lowland South America provides a rare opportunity for collaboration betweengeologists, biologists, and anthropologists. As Swadesh observed years ago, "The separate linesof study serve to verify or correct one another and to fill in details of the story" (1952:453).In Amazonia the archaeological record begins with the introduction of pottery. Whereas260 [Vol. 44, No. 2,1979
  11. 11. CLIMATICOSCILLATIONINAMAZONIANPREHISTORYlanguagesleave no markonthe soil,potteryremainswhere it was discarded.We mayargueoverthe "homeland"of a familyof languages,butidentificationof the "homeland"of a ceramictradi-tion must take account of the locations and ages of sites with related pottery.The sites and complexes with the earliest dates in various parts of northern South America areshown in Figure 7. Complexes beginning + 5000 B.P. have been reported on the coasts of Ecuador(Valdivia),Colombia(PuertoHormiga),andBrazileast of the mouthof the Amazon(Mina).Datesof + 4000 B.P have been obtained from east-central Peru (Waira-jirca), eastern Ecuador(Pastaza), and western Panama (Monagrillo). The beginning of the third millennium B.P. saw theappearance of pottery on the lower Orinoco (Ronquin Sombra and Barrancoid), at the mouth ofthe Amazon(Ananatuba),and possiblyon the central coast of Brazil(Periperi).Thereliabilityofthe earliest date from the central lowlands, + 2400 B.P. (Paredao), is uncertain, but several sitesnear the junction of the Negro with the Amazon establish that pottery was in use by + 1800 B.P.RONQUIN SOMBRA2970 t 85(I-9971)Figure 7. Location and antiquity of the earliest ceramic complexes known from South America, com-pared with the present limits of Amazonia. The oldest occurrences are along the northwestern margin ofthe continent, implying dispersal into the lowlands contrary to Lathraps reconstruction. Except forParedao, all the complexes incorporate decoration only by incision, excision, punctation, and other plastictechniques. Most have been interpreted as offshoots of the Andean Formative tradition. (Limits of thehumid forest after Meggers 1971.)Meggers] 261
  12. 12. AMERICAN ANTIQUITYComplexes dating + 2000 and ? 1650 have been reported from the lower Amazon (Poco) and thelower Xingu (Macapa). Pottery from the Japura, in the northwest lowlands, dates ? 1300 B.P. Ex-cept for shell middens of the Periperi tradition, the earliest ceramics in eastern Brazil have an an-tiquity similar to those in the central Amazon; several traditions appear between ? 1840 (Ta-quara, Una) and ? 1650 B.P. (Papeba).With one exception (Paredlo), these initial ceramics are characterized by the absence ofpainted decoration and the presence of broad incision, excision, punctation, and other plastictechniques, used alone or in combination. A relationship has been recognized between Valdivia,Puerto Hormiga, and Monagrillo (e.g., Willey 1971:489-490; Ford 1969; Meggers et al. 1965), andFord postulated the spread of this early tradition to theissoutheastern United States. Meggers andEvans (1978) have suggested that the Mina phase reflects a contemporary dispersal along thenorthern coast of South America. Although the Barrancoid style is aberrant in emphasizingelaborate adornos, it exhibits numerous features implying derivation from Andean Formativeantecedents (Sanoja 1977). The Ananatuba phase has also been linked with the Andean For-mative tradition (Willey 1971), and relationships to Valdivia have been proposed for the Pastazaphase (Porras 1975), the Poco phase (Hilbert and Hilbert 1979), and the Taquara tradition (Miller1971). Many of these connections are accepted by Lathrap (1974:143), who terms the various ex-pressions "stylistic cousins" and specifies northwestern South Ameria as "cultural donor" toboth Mesoamerica and the Central Andes between 3100 and 1300 B.C. (1974:145).Pottery from archaeological sites dating within the Christian Era exhibits tremendous variationin techniques, motifs, and frequencies of decoration, implying a complicated history. A fewgeneral traditions have been recognized, all of which have distributions outside Amazonia. ThePolychrome tradition has affiliations with complexes in western Venezuela and the highlands ofColombia (Meggers and Evans 1978); numerous dates indicate it dispersed between ?+ 2000 and? 600 B.P. The Incised-and-Punctate tradition shares techniques and motifs with pottery fromcentral Venezuela and the Antilles (Meggers and Evans 1978; Lathrap 1970:Figures 41-43); itsdiffusion appears to have occurred after ? 1500 B.P.Do any of these patterns coincide with linguistic distributions or episodes of environmentalstress implied by the refugia model? One coincidence is suggestive: the spread of pottery makingeast of the Andes seems to have occurred during the Holocene arid interval. With the exception ofthe Mina phase, all complexes dating before + 4000 B.P. are along the northwestern margin ofSouth America. Pottery appears at the mouths of the Orinoco and the Amazon at ? 3000 B.P.,midway between the estimated inception and termination of the last period of fragmentation ofthe forest. Did the existence of more open vegetation facilitate movement into the lowlands bypottery-making groups adapted to this kind of habitat?Later ceramic complexes assigned to the same tradition are more heterogeneous here than onthe Brazilian coast, suggesting more numerous sources and higher intensities of acculturation.This diversity may be the cultural counterpart of hybridization observed for the fauna. The cen-tripetal pattern of dispersal exhibited by all the ceramic traditions is another characteristicshared with the flora and fauna (Haffer 1974:150, 154). Can we reject the hypothesis of a commoncause?SCIENTIFICMETHODOLOGYData derive their significance from the manner in which they are perceived. Whitten is no morelikely to be convinced of my interpretations than I am of his because we perceive the data dif-ferently. I assumed that those who might read my discussions shared the premise that changes inthe environment are likely to affect human communities, since such correlations have beendemonstrated repeatedly by archaeologists (e.g., Aikens 1978; Wedel 1978; Fitzhugh 1977; Brysonand Murray 1977). Whitten, however, labels this kind of explanation "deus ex machina" and re-jects it in favor of a reconstruction by Lathrap, which he finds more "satisfying." Let us comparethe two models.Lathrap bases his reconstruction on the assumption that cultivation of root crops had become262 [Vol. 44, No. 2,1979
  13. 13. CLIMATICOSCILLATIONINAMAZONIANPREHISTORYso productive by ? 5000 B.P. that it caused an explosion of the population on the middle Amazon.Pottery was invented and "rather early extruded from the Amazon Basin" to the coast ofEcuador, accounting for the appearance there of the Valdivia tradition. Other groups moved upthe Negro and down the Casiquiare to the coast of Venezuela or up the Madeira to the easternslopes of the Andes. Lathrap further assumes that intensification of food production continued"so that even greater population pressures began to build up." These were relieved by new wavesof emigration between ? 3000 and 2500 B.P. The development of the Saladoid, Barrancoid, andPolychrome traditions in the central Amazon and their wide dispersals are expectations "in-herent in our general model of population dynamics [which] is that the flood plain of the CentralAmazon has long been an area of dense population, indeed over-population; and that it was thesource rather than the recipient of most of the major population movements. Such a demographicsituation should have resulted in a continuous and gradually evolving cultural tradition" (Lathrap1970:67, 74-75, 112-127, 156-158; see also 1977).Accepting this reconstruction requires accepting Lathraps two assumptions: (1) that intensiveagriculture was being practiced on the middle Amazon by ? 5000 B.P. and (2) that it caused un-controlled increase in population, creating pressures relieved by continuous outward migration.No direct or indirect evidence exists for either assumption (see, e.g., Pickersgill and Heiser 1977).Indeed, Lathrap has subsequently designated the Caribbean lowlands of Colombia as a more like-ly candidate for "cultural donor" (1974:145; cf. Meggers 1963:136-137). Archaeology hasdocumented the arrival of Tupi-Guaranian speakers on the south coast of Brazil by ? 1400 B.P.,negating Lathraps hypothesis of a late dispersal from the lower Amazon (Figure 4). The pattern-ing of the initial dates for pottery making in the continent as a whole is not compatible with its ori-gin in Amazonia (Figure 7). Even if we consider this evidence inconclusive, we can still evaluatethe relative merits of Lathraps reconstruction and the refugia model.In the physical and natural sciences, the hypothesis that accounts for the largest variety ofphenomena is considered the most acceptable. The refugia model is compatible with a wide rangeof edaphic, geological, geomorphological, climatological, biological, and cultural data. The impactof oscillations in the environment on the biota can be predicted from evolutionary theory, andvariations in expression can be explained in terms of generation length, dispersal capacity, selec-tion pressure, and other kinds of differences in the organisms and the environments. The refugiamodel not only provides a basis for understanding evolution in the humid tropics but also permitsa more consistent reconstruction of global conditions during the Quaternary. It is now evidentthat the tropical lowlands experienced drastic climatic fluctuations of the kinds observed athigher latitudes, rather than remaining unaltered throughout the Pleistocene as was previouslybelieved. Periodic fragmentation of the humid forest becomes an understandable and predictableconsequence of climatic perturbations of global magnitude, just as continental drift became a ne-cessary assumption after the discovery of plate tectonics (Gould 1977:160-167). Lathraps model,by contrast, sets Homo sapiens apart from the ecosystem and postulates a unique course forcultural history in Amazonia. The conflict between this "Human Exceptionalism Paradigm" andthe premise that cultural evolution is a form of general evolution underlies many current dis-agreements among social scientists (cf. Price 1978; Schneider 1977; Catton and Dunlap 1978).Another difference between Whittens outlook and mine is implied by the negative tone of his"comment." He appears to consider any inaccuracy in the refugia model grounds for its rejection.Haffers suggestion that rainfall patterns might have been the same during the Pleistocene as theyare today has proved wrong, but this does not invalidate the whole hypothesis. A century afterDarwin published his Origin of Species, biologists are still correcting misconceptions about theoperation of natural selection. A scientific theory should call attention to unobserved rela-tionships, which in turn suggest new avenues for exploration. For me, the many uncertainties inthe refugia model are less important than its positive aspects. It brings order out of chaos, revealsunsuspected patterns of similarity in different categories of cultural phenomena, and provides ex-citing leads for investigation. Helping to improve its accuracy should be both challenging and fun.Acknowledgments. I amgratefulto the followingarchaeologists,whose unpublishedcarbon-14dates are263Meggers]
  14. 14. AMERICAN ANTIQUITYcited in Figures 4, 6, and 7: Jose Proenza Brochado, Valentin Calder6n, Igor Chmyz, Ondemar Dias, Peter PaulHilbert, Eurico Th. Miller, Nassaro A. de Souza Nasser, Celso Perota, Walter F. Piazza, Pedro IgnacioSchmitz, and Mario F. Sim5es.REFERENCES CITEDAbSaber, Aziz N.1977 Espa9os ocupados pela expansao dos climas secos na America do Sul, por ocasiao dos glaciaisquaternarios. Paleoclimas 3. Instituto de Geografia, Universidade de Sao Paulo.Aikens, C. Melvin1978 The far west. In Ancient native Amerians, edited by Jesse D. Jennings, pp. 131-181. W. H. Freeman,San Francisco.Andreyev, Nikolay Dmitriyevich1962 CA comment. Current Anthropology 3:130.Bergsland, Knut, and Hans Vogt1962 On the validity of glottochronology [with CA comment]. Current Anthropology 3:115-153.Bigarella, J. J.1971 Variacoes climaticas no quaternario superior do Brasil e sua datacgo radiometrica pelo metodo docarbono 14. Paleoclimas 1. Instituto de Geografia, Universidade de Sao Paulo.Brown, Keith S., Jr.1977 Centros de evolucAo, reffigios quaternarios e conservacao de patrimonios geneticos na regiaoneotropical: padroes de diferenciacao em Ithomiinae (Lepidoptera: Nymphalidae). Acta Amazonica7:75-137.Brown, Keith S., Jr., P. M. Sheppard, and J. R. G. Turner1974 Quaternary refugia in tropical America: evidence from race formation in Heliconius butterflies. Pro-ceedings of the Royal Society 187:369-378.Bryan, Alan L.1973 Paleoenvironments and cultural diversity in Late Pleistocene South America. Quaternary Research3:237-256.Bryson, Reid A., and Thomas J. Murray1977 Climates of hunger; mankind and the worlds changing weather. University of Wisconsin Press,Madison.Carbone, Victor A.1978 The paleoecology of the Caribbean area. Paper presented at the 1978 Simposio sobre Problemas dela Arqueologia Antillana, Universidad Catolica de Puerto Rico, Ponce.Catton, William R., Jr., and Riley E. Dunlap1978 Environmental sociology: a new paradigm. American Sociologist 13:41-49.Chretien, C. Douglas1962 The mathematical models of glottochronology. Language 38:11-37.CLIMAPProject Members1976 The surface of the ice-age earth. Science 191:1131-1137.Damuth, J. E., and Rhodes W. Fairbridge1970 Equatorial deep-sea arkosic sands and ice-age aridity in tropical South America. Bulletin of theGeological Society of America 81:189-206.Descamps, M., J. P. Gasc, J. Lescure, and C. Sastre1978 Etude des ecosystemes guyanais, II. Donnees biogeographiques sur la partie orientale des Guyanes.C. R. Soc. Biogeogr. 467:55-82.Diebold, A. Richard, Jr.1960 Determining the centers of dispersal of language groups. International Journal of American Linguis-tics 26:1-10.Dyen, Isidore1956 Language distribution and migration theory. Language 32:611-626.1971 Review of Istivan Fedor: The rate of linguistic change. International Journal of American Linguistics37:130-134.Eden, M. J.1974 Paleoclimatic influences and the development of savanna in southern Venezuela. Journal of Bioge-ography 1:95-109.Fairbridge, Rhodes W.1976 Shellfish-eating preceramic Indians in coastal Brazil. Science 191:353-359.Fitzhugh, William W.1977 Population movement and culture change on the central Labrador coast. Annals of the New YorkAcademy of Sciences 288:481-497.Ford, James A.1969 A comparison of Formative cultures in the Americas. Smithsonian Contributions to Anthropology 11.264 [Vol. 44, No. 2,1979
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