Prehistoric Intensive Agriculturein the Mayan Lowlands

Examination of relic terraces and raised fields indicatesthat the Rio Bec Maya were sophisticated cultivators.

B. L. Turner ll

The ancient lowland Maya havebeen traditionally portrayed as swid-den (shifting cultivation) agricultural-ists (1). The persistence of the swid-den concept has inhibited field inquiryof past modes of lowland subsistence,often preserving what may be an un-founded bias concerning the cultiva-tion techniques employed by the Maya.Moreover, the absence of adequatesubsistence research has, in effect,supported traditional views regardingsuch issues as prehistoric populationsize (2) and the collapse of the ClassicMaya civilization (3).The last few years have witnessed

increased opposition to the swiddenconcept (4). Antagonists have beenstimulated by the discovery of ancientforms of intensive cultivation (5) invarious parts of the New World tropicswhich have hitherto been consideredsparsely utilized (6) and by the intro-duction of revamped theories of thedevelopment of agriculture (7, 8).Boserup's (7) contention that thegrowth of agriculture from extensiveswidden to intensive multicrop cultiva-tion is a direct response to populationpressures has been particularly sig-nificant, encouraging reexamination ofMayan subsistence (9).The theories of agricultural develop-

ment set forth by Boserup and modi-fied by Brookfield (8) are especiallyimportant to the question of Mayansubsistence in light of lowland demo-graphic evidence. Studies by Willeyet al. (10, p. 576), Bullard (11),Haviland (12), and others suggest thatspecific Mayan regions once supported

The author is a doctoral candidate in thedepartment of geography at the University ofWisconsin, Madison 53706.

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large numbers of people. Althoughprehistoric population estimates mustbe viewed in relative terms, indicationsare that several lowland groups ex-ceeded the supportive limits of forest-or bush-fallow systems of swiddencultivation (2, 13). It is plausible toassume that, in instances of demo-graphic pressure, more intensive formsof cultivation were adopted or devel-oped by the Maya, a position acceptedby a seminar on the collapse of theClassic Maya civilization (14).

Based on research in 1973 withinthe Rio Bec region of southern Cam-peche and Quintana Roo, Mexico(Figs. 1 and 2), this article examinesnew evidence of intensive Mayan agri-culture, in the form of terraces andraised fields. These prehistoric tech-niques of lowland cultivation are de-scribed and their significance dis-cussed (15).

Previous Indications of

Intensive Agriculture

Evidence of intensive agriculturewithin the Mayan lowlands is not ab-sent in the literature. Historical ac-counts describe the existence of irriga-tion networks along the Motagua andUlua rivers of Guatemala and Hon-duras respectively (16). Lundell (17,p. 73) has recorded stone markers onthe forest floor of southern Campechenear Tuxpefia and suggests that thesefeatures are relics of intensive agri-cultural activities by the ancient Maya.Check dams, or terraplenes agricolas,are reported in various sectors of theRio Bec region of Campeche by Rup-pert and Denison (18, pp. 13 and 50)

and in Belize and the Peten district ofGuatemala by Blom (19). Althoughlong noted, these features have re-ceived minor attention.The presence of relic terraces in

the Maya Mountains of Belize are welldocumented. These structures werenoted in 1927 by Ower (20, pp. 383-384) and have since been describedby several scholars (21, pp. 228-229;22, 23). Despite the proximity of theBelize terraces to such lowland popula-tion centers as Tikal and the Belize-Mopan River valley, their significanceto Mayan subsistence is almost totallyignored by proponents of a swidden-based Mayan civilization.

Relic raised fields have been recentlyLincovered in the poorly drained flood-plains of the Candelaria River in south-western Campeche and in northernBelize by Siemens and Puleston (24).These discoveries add a new dimensionto lowland Mayan agriculture, illumi-nating past adaptation and utilizationof riverine environments.

Rio Bec

The Mayan cultural region of RioBec is located in the southeasterncorner of Campeche and adjacent por-tion of Quintana Roo. The regioncontains a large number of rural house-mounds and several large ruins, includ-ing the fortified site of Becan. Thislarge center and the region surroundingit have received considerable examina-tion by field projects of the MiddleAmerican Research Institute, TulaneUniversity (25).The physical setting of the Rio Bec

area offers a variety of local environ-ments to which past cultivatorsadapted. Local relief is dominated bylimestone hills 20 to 60 meters highwith varying slopes up to, but rarelyexceeding, 500. The uplands containrelatively well-drained but shallow soilswhich are highly vulnerable to erosionwhen exposed to the torrential rainsof the wet season. Level terrain isgenerally restricted to depressions,either large wooded bajos (low areas)or small savannas, where drainage isretarded by thick deposits of subsur-face gray clays. Seasonal inundation ofthe lowlands creates soil conditionswhich are too wet and sticky for swid-den agriculture. Permanent cropping ofeither type of terrain, upland or low-land, necessitates one of two specificcultivation measures: minimization ofsoil erosion or drainage.

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Terraces an(l Associated Features

Tens of thouLsands of relic terracescrisscross the hillsides of souLthernCampechle and QUintana Roo, encom-passing an area exceeding 10,000s(luare kilometcrs. Rio Bec terracingwas recorded radiating north fronXpLjil1, Campeche, 62.5 kti; souLth, 13.8kin; east, 77.7 km; and west, 96.2 km(26, 27). The fr-equlellcy of terracillnvxaries throuLghouLt the region. By fat-the greatest nuLImber of terraced slopesare located along an cast-west axis fromNicolis Bravo, Qulintiania Rloo. toXpu,jil.

Accordincg to the classificationi de-\,eloped by Spencer anid Hale (28, p.6), the Rio Bcc terraces are predomi-nantly the linear sloping, dry fieldvai-iety that include: the "rock-em-baniked buLt noni-contouLred terrace witha sloping field laid across slope, with-oLIt facilities for artificial water, de-pendelnt ulpon natuiral precipitationl forsoil water." Figure 3 illistrates a hil-sidc profile of this type of terraciig.I he slope is broken by embanikmeintswhich collect eroding soils, creaitiligsmiiall, level (or near-level) sectionis ofland which extenid 1 to 5 m behind theterrace wall. Each terraced area, then.is sloping, with thinner soils immedi-ately in front of a terrace wall andthicker soils behinid. AlthouIgh indi-vidual terrlaces may ruIn somilewhat di-agonally across the slope, they mor-ecommonily display a contouired patteirn.As a ruIle, terraces conforimi better tohillside conitotirs as the degree of slopesteepeins.The check daimi type of terirace re-

ported by RuIppert anid Denison (18)OCCIIS less frequLently thani the linearsloping variety. Fouind in hillside ra-vines, check dams appear to closelyresemble the channel bottom weir ter-Iraces (28) which have been noted invarioLIs sectors of the Mayan lowlands(19 ). Weir terraces are laid acrossdrainage channels and capture silt-ladenruInoff. As stich, they create nearlylevel areas of soil behind each terrace.Two distinct construictional forms of

terrace cmbankments have beenl uincov-ered. Eastward from Becan, embank-mIeCnts consist of CUt limestone wallsanid ruibble fill (Fig. 4). Fronting wallsare construicted of small, dry-laid lime-stonie slabs, creating an embankmenit80 to 140 centimeters in height. Behindthis, a ruibble fill of rocks is deposited,similar to some of the ancient terracesof the Andes (29, p. 494; 30, p. 211).The entire embankment. wall and fill. is

12 JUL Y 1974

Fig. 1. Nllap of the central Mayan low lands and the Rio Bec region.

Fig. 2. Map of the Rio Bec study area showing the locations of identified terracesand raised fields. Terrace locations aie only those surveyed from the ground and, thus,reflect those areas currently cleared for agricultuial use. Aerial reconnaisance revealedlarge zones of terracing north and south of Route 186, particularly between Becan-Xpujil and Nicolas Bravo.

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0 0 a Terrce embankmentt D Stone wallterrace Accumulted terrace soil

--------------,.-, A,

b '0'4o' 6 80 100Motors

Fig. 3. Hillside profile of linear- slopin*gterriices IX km east of Xptijil.

80 to 300 cm wide at the base.To the west of Becan, terrace em-

bankments are generally smaller andlack a well-defined section of rubblefill. Embankments are composed ofeither dry-laid limestone walls, or rowsof upright rock slabs. The slab-typeterrace is built of large cut stones sunkapproximately 20 cm into the ground.These embankments rarely exceed 40cm in height and their basal widthfluctuates from 60 to 80 cm. This con-structional form displays a striking sim-ilarity, particularly in a decayed state,to the "linear border" type of relicterrace common to regions of the souLth-western United States (31 ).

Terraces occur on hillsides varyingin slope from 40 to 47°. In most in-stances, slopes exceeding 50° are voidof terracing. As expected, the distancebetween embankments is directly re-lated to the degree of slope and, withminor exceptions, decreases as theslope increases. The following distancesbetween terrace embankments havebeen recorded: 42.24 m at slope anglesof from 40 to 140; 24.10m at 150 to290; and 19.00m at 30° to 47°.

Linear ridges running up- and down-slope are common in the eastern sectorof the study area. Such ridges are com-posed of parallel, dry-laid limestonewalls separated by rubble fill. Theheights of the ridge vary from 80 to130 cm, while basal widths range from200 to 400 cm. These structures areconnected to larger terrace embank-ments, creating a network of walkwayssimilar to those described in the ter-raced regions of the Andean loinas(32). When walkways are frequent onlong, gentle slopes, terraced areas dis-play a deceptive lattice pattern fromthe air (Fig. 5).

Other terrace-associated features in-clude small rock walls laid diagonallyacross the slope, stone platforms, andhousemounds of various sizes. The lat-ter features are particularly frequent,with an average of one housemoundfor every 0.75 hectare of terracedhillside. Common in the immediate

vicinity of Becan are linear stone anddirt ridges. Apparently nonagriculturalin function, these structures are re-stricted to sections of level, non-inundated terrain. More detailed de-scriptions of these ridges are forth-coming and, thuLs, will not be treatedin this article (33).

Functions

The relic terraces of southernCampeche and Quintana Roo wereprobably constructed as impedimentsto the erosion of the very shallow (5to 45 cm) topsoils common to theregion. The continual clearance and ex-posure of slope soils 'to annual extremi-ties in precipitation created physicalconditions highly susceptible to soilerosion. To counteract the erosive forceof rainfall and to maintain fertile hill-side soils, the Rio Bec Maya built rockand rubble embankments, or soil-trapterraces (34, 35). Each embankmentcaptured the earth washed downslope,creating soil deposits of 25 to 45 cmin depth. The manner in which thetrapped soil was utilized has not beendetermined, although several possibili-ties exist: (i) it served as a superiorculltivation medium for a dominantcrop, perhaps maize, which was proba-bly also planted throughout the entireterraced section; (ii) it provided anadequate soil depth for the cultivationof root crops, maize having beenplanted on the thinner upslope soils; (iii)it was carried upslope and depositeduniformly over each terraced section.In any case, the soils were maintainedand used on hillsides, not washed away.

Drainage was undoubtedly an im-portant fuLnction of both terraces andassociated features. The concentrationof runoff behind terrace embankments,particularly during the daily showersof the rainy season, inundated sur-rounding soils and damaged the ter-race wall. To combat these hazards, atleast three drainage techniques wereemployed: guide walls, seepage outlets,and laterally sloping embankments.Walkways and small stone walls

acted as devices to control the distribu-tion of runoff water. These structuresdivided terraced slopes into quadri-lateral compartments in which precipi-tation was contained, maintaining abalance of water over the hillsides. Toprevent constructional damage withineach terrace compartment, embank-ments were built so as to facilitatedrainage. A rubble fill was deposited

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Fig. 4. The downslope face of a Rio Becterrace. Note the rubble-fill drainage sys-tem immediately behind and below theterrace wall.

behind and below each terrace wall toprovide a medium for the seepage ofrainwater under the embankment anddownslope (Fig. 4). A similar drainagetechnique was apparently utilized bythe Incas as well (30, p. 211). Fur-thermore, terrace embankments wereconstructed with a slight lateral slope,which allowed excessive runoff waterto flow along the embankment to col-lection points. Whether the collectedwater was drained downslope is tin-determined.The connective system of terraces

and walkways functioned as a trans-portation network. Terraces joined bywalkways were generally larger thanother terraces, offering pathways ofwidths exceeding 100 cm. Such an ele-vated transportation network main-tained three distinct advantages overground-level pathways. It (i) kept traf-fic away from cultivated fields wherecrop damage might have occurred, (ii)eased walking conditions over terraceembankments; and (iii) facilitatedmovement over muddy terrain duringthe long wet season.

Other possible terrace functions in-clude the creation of a level plantingsurface and field clearance. The estab-lishment and maintenance of a levelplanting surface was either an explicitor implicit function of the terraces.Trapped soils created level surfacesextending 1 *to 5 m behind each em-bankment, depending on the degree of

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slope. The significance of these levelsectors to Mayan cultivation has notbeen determined.

Terrace embankments might wellhave functioned as receptacles for rockand other field debris. This material.collected from cropping surfaces tofacilitate cultivation, may constitute therubble-fill segment of the terraces. In-deed, incipient terracing might haveresulted from the collection and depo-sition of such field debris.

Raised Fields

Raised fields, often called ridged ordrained fields, "include any preparedland involving the transfer and eleva-tion of soil above the natural surfaceof the earth in order to improve culti-vating conditions" (36, 37). This agri-cultural technique is widely distributedamong indigenous tropical cultivators(36) and was important to numerouspre-Columbian Amerinds (6). Rem-nants of raised fields have tentativelybeen identified in the Bajo del Moro-coy, a large, wooded, lowland areanortheast of Nicolas Bravo (Fig. 2).Aerial reconnaissance and photographsreveal a checkerboard pattern of ele-vated platforms covering an area inexcess of 120 km2. Because of thethickness of bajo vegetation, a thoroughexamination of these earthworks willnecessitate considerable clearing. Un-fortunately, the raised fields that werediscovered lay immediately outside theresearch permit zone, prohibiting landclearance as well as archeological in-vestigation (38).Mayan raised-field cultivation was

conducted in seasonally inundated low-lands where soils were often highlyfertile but poorly drained (34). Pro-longed inundation, often 4 to 5 monthsin duration, created waterlogged soilsnot suitable for cropping. To providea medium for cultivation, the Mayaconstructed raised, dirt platforms andan associated network of drainagecanals. This system of platforms andcanals facilitated drainage, establishinga drier cropping surface above the levelof standing water.

Tropical cultivators maintain anacute awareness of the varying agri-cultural functions provided by raisedfields. Other than drainage, "these in-clude the enhancement of soil fertilitythrough pulverization and through theconcentration of organic matter andtop soil, modification of micro-climate,control of weeds, control of erosion,12 JULY 1974

Fig. 5. Aerial photograph of a terrace system near Nicolas Bravo. When walkwaysare frequent on long, gentle slopes, terraced areas display a deceptive lattice pattern.

and facilitation of harvesting" (36).Comparisons with contemporary dataon tropical cultivation suggest that theMaya possessed methods of increasingand maintaining soil fertility, such asmulching, which were applied to ter-raced as well as raised fields. Further,the dominance of root crops withintropical raised-field agriculture (36)lends support to the contention thatthese cuLltigens were important toMayan subsistence (39).

Reconstruction of the Agricultural

Sequence

The relic terraces and raised fieldsof and near the Rio Bec region aretestimonials to past intensive agricul-ture in the Mayan lowlands. These fea-tures were constructed to facilitate an-nual or near-annual cultivation. In thismanner, the frequency of cultivation,or intensity of agriculture, was vastlyincreased. That these features wereutilized for a system of long-fallowcultivation seems highly improbable.The time and labor expended to con-struct and maintain the structures weretoo great to justify lengthy fallowperiods. It should be noted that theuse of stone terraces and raised fieldsin other regions of the world is asso-ciated with agricultural systems inwhich the frequency of cultivationexceeds the frequency of fallowing.

Terraces and raised fields representforms of land reclamation necessitatedby the demand for increased agricul-

tural production. In the Rio Bec regionthis demand was most likely stimulatedby enlarging populations during theBejuco (Late Classic) period, aboutA.D. 600-730 (40, 41). The incipientstages of intensive cultivation, how-ever, began at an earlier date.The sequence of agricultural devel-

opment within the Rio Bec region,then, quite conceivably followed thestages of growth delimited by Boserup(7). Initial cultivators in the area pur-sued a forest-fallow method of swid-den agriculture wherein a forest plotwas cleared and planted for severalyears until decreased soil fertility andweed invasion lowered yields. The plotwas then left to fallow until some mea-sure of fertility was regained.

Population pressures and, hence, pro-duction demands increased during thePakluum (about 200 B.C.-A.D. 250)and Chacsik (about A.D. 250-500)phases of Rio Bec occupation. To com-bat rising demands, the length of thefallow periods was shortened, allow-ing more land to be simultaneouslycultivated. With each appreciable cutin the fallow period, measures to main-tain adequate soil depth and fertilityand to control weeds were necessarilyadopted or developed. Cultivation mayhave reached the grass-fallow stagesduring the latter Chacsik phase (2, p.344).

Analysis of ceramics taken from ter-race fill and associated housemoundsindicates that initial terrace construc-tion began during the Sabucan phase(about A.D. 500-600) (42). Large-

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scale construction of terraces and, per-haps, raised fields during the Bej'ucoperiod paralleled a marked increase inthe population of the region. Inter-estingly, in this period there was aprobable influx of groups from south-ern Quintana Roo and Belize (40).Whether these groups brought raised-field agriculture with them is not known.

Intensive agriculture was apparentlymaintained into the Chintok period(about A.D. 730-830). As populationpressures and production demands be-gan to dwindle during the Xcocomphases (about A.D. 830-1050), agri-culture regressed through various stagesof less intensity until such a time thatextensive, swidden systems of cultiva-tion could sustain the populace. Swid-den cultivation, ranging from forest-fallow to bush-fallow systems, has re-mained dominant to this day.The temporal sequence of agricul-

tural activities within the Rio Bec re-gion is, no doubt, the result of a morecomplex set of circumstances than asimple association between populationand agricultural demand (8). Environ-mental factors, foreign intervention,and time lags between increases in de-mand and the intensity of cultivationare variables which may have alteredthe sequence somewhat. However, thebasic outline presented should remainlittle changed: (i) a gradual increasewith minor fluctuations in the intensityof agriculture up to and during theBejuco and Chintok periods, followedby (ii) a decrease in such intensity last-ing to modern times. With revisions oftime and place, this temporal sequenceshould be applicable throughouLt thecentral Mayan lowlands.

Population Implications

Demographic reconstructions of pre-historic Mayan populations must beviewed with caution, as they are con-tingent upon assumptions and interpre-tations. Exemplary are attempts to as-sess the agricultural potential, or carry-ing capacity, of the lowlands as a mea-sure of potential population limits.Such reconstructions are characterizedby the application of contemporaryswidden cultivation data to the past.This necessitates numerous interpreta-tions, often conflicting, regarding thelength of the swidden cycle, crops andproductivity, and the availability of cul-tivable land (43, 44).The presence of relic terraces and

raised fields adds a new perspective to

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assessments of the carrying capacity ofthe central lowlands. These agricul-tural structures are indicative of an-nual or near-annual cropping and in-creased productivity, if weeding andmulching or other fertility measureswere conducted. Further, the intensivetechniques considerably increased theavailability of cultivable land. Raisedfields are particularly significant, astheir construction made possible thecultivation of inundated regions in thecentral lowlands. Examples illustratethe increased population limits estab-lished by the potential production ofintensive agriculture.

Vogeler (45) estimates a populationceiling of 28 to 85 persons per squarekilometer (73 to 220 per square mile)for a zone in the center of the Rio Becarea. This estimate is based on con-temporary data on swidden cultivationapplied to Conklin's (46, p. 63) mea-sure of critical population size (carry-ing capacity) of the land. An extraordi-nary 7-year swidden cycle (3 years ofcrops, 4 years of fallow) is operativein which 0.5 ha of land can sustainone individual for 1 year. The ceilingvariance results from the estimate ofcultivable land, either 25 or 75 percentof the total area considered.

If the contemporary subsistence fig-ure of 0.5 ha is applied to a 1-year,intensive-agriculture cycle, an estimateof the potential population size isgreatly increased. If 75 percent of theland was cropped, the potential popu-lation ceiling is raised to 150 personsper square kilometer (47), a figure inline with Sanders' (2, p. 332) estimateof peak lowland population densities.In light of the agricultural techniquesutilized by the Rio Bec Maya, an esti-mate of 75 percent for the potentialcultivable land area is not excessive.Housemound studies suggest that in

certain Mayan areas populations weremaintained in excess of the demo-graphic limits estimated from contem-porary investigations of the potentialof swidden cultivation. Housemoundcounts from the PetZen region indi-cate possible rural-like populationdensities ranging from 40 to 200 peo-ple per square kilometer (10, p. 577;11, p. 366) and urban-like centersmaintaining 600 to 700 inhabitants persquare kilometer (12). The increasedestimates of critical population size de-rived from evidence of intensive culti-vation of the central lowlands lendcredibility to the housemound studies,illuminating the possibility of large anddensely populated Mayan groups.

Agricultural Methods andthe Mayan Collapse

Numerous theories, ranging from in-ternal peasant revolt to climatic change,have been offered as explanations ofthe collapse of the Classic Maya civili-zation (48). Although currently in dis-favor, theories connecting the collapseto Mayan agricultural pursuits havepersisted. Such explanations suggestthat the continual and unaltered reli-ance on swidden methods of cultiva-tion uiltimately created cropping condi-tions with which the Maya could notcope.

Specifically, agricultural-collapse the-ories contend that increased demandfor agricultural produce necessitated re-ductions in the length of the swiddenfallow periods. This impeded the re-turn flow of nutrients to swidden plots,creating exhausted soils unable to sus-tain an adequate production level (49).Alternatively, it is suggested that theextensive cutting and burning requiredby swidden cultivation converted thelowland forests into grasslands whichthe Maya, lacking the proper technol-ogy, were unable to crop (50). Also,it has been suggested that, if no pre-ventive measures were taken, soil ero-sion may have played a contributingrole in the collapse (2, p. 377).The evidence of intensive agriculture

gathered from Campeche and QuintanaRoo raises questions about the validityof swidden-collapse theories as appliedto the Rio Bec Maya. The abundantpresence of relic terraces and raisedfields imply that Rio Bec cultivatorswere not inhibited by a lack of agri-cultural know-how. Rather, they de-vised or adopted numerous methodswhich allowed a reduction in the fallowperiod, maintained soil fertility, depth,and drainage, and controlled grass in-vasion. Such measures were accom-plished with nothing more than chertand obsidian cutting tools, diggingsticks, and baskets (51). Furthermore,if terraces and raised fields prove to beas common throughout the central low-lands as they are in the Rio Bec region,the validity of swidden-collapse theoriesmust be questioned in terms of the en-tire Classic Maya civilization (52).The concept of intensive lowland

cultivation lends support to severalpreviously suggested collapse theories,those concerning environmental ramifi-cations and monocropping disasters.According to the former, large sectionsof the lowlands were stripped of forestvegetation, and drainage patterns were

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altered. Such physical tampering mighthave led to short-term, but large-scale,environmental repercussions to whichthe Mayan farmer did not have suffi-cient time to adjust. More plausible,however, is the possibility of a mono-cropping disaster. Throughout theworld, intensive cultivation is associ-ated with specialization in crop as wellas in cultivation technique. Overempha-sis on terrace maize, or raised-field rootcrop, production might have left thelowlanders' crops vulnerable to dis-eases and pests and consequent fail-ures, a less severe problem under swid-den cultivation wherein fields arewidely scattered (53).

Perspective

Historic and contemporary theoriesconcerning the subsistence techniquesemployed by the ancient lowland Mayaare largely speculative or based onmeager data. The field research onrelic agricultural structures presentedhere demonstrates that this situationneed not exist. Remnants of terracesand raised fields are common through-out southern Campeche and QuintanaRoo, indicating that the Rio Bec re-gion was inhabited by sophisticated,intensive cultivators. Based on otherreports (17, 24), it seems appropriateto apply this assessment to various othersectors of the Mayan lowlands, includ-ing Belize and the Peten region ofGuatemala (54). In areas where ter-racing or raised fields do not occur, aless intensive bush- or grass-fallow sys-tem of agriculture may have been pur-sued (2). Hence, the contention thatthe lowland Maya, restricted by a hos-tile environment, never progressedbeyond swidden cultivation is invalid.

Tentative assessment of the collectedRio Bec data suggest that Mayan agri-culture progressed through variousstages of intensity from forest-fallowswidden to annual cultivation. The in-tensity and extent of cultivation mostlikely peaked in association with en-larging populations during the LateClassic period. In the Rio Bec region,this climax took place during Bejucoand Chintok times (about A.D. 600-830). The ensuing collapse of the low-land civilization was not a result ofprimitive farming techniques, althoughagricultural ramifications may haveplayed a contributing role.

Continued research should illuminatepast Mayan agricultural pursuits, pro-viding more precise data about farming

12 JULY 1974

activities and crops utilized, the arealextent of intensive cultivation, and thetemporal sequence of agricultural de-velopment. A more accurate and com-plete description of lowland subsistencewill contribute to a more thoroughcomprehension of Mayan civilization.

References and Notes

1. The list of proponents of swidden Mayanagriculture is lengthy, and at various timesit has included most scholars who have de-voted attention to Mayan agriculture. Exem-plary are G. R. Willey and W. R. Bullard[in The Handbook of Middle American In-dians, vol. 2, Archaeology of Southern Meso-america, G. R. Willey, Ed. (Univ. of TexasPress, Austin, 1965), pp. 372-373] and M. D.Coe [The Maya (Thames & Hudson, London,1966), p. 138].

2. W. T. Sanders, in The Classic Maya Collapse,T. P. Culbert, Ed. (Univ. of New MexicoPress, Albuquerque, 1973), p. 325.

3. S. G. Morley, The Ancient Maya (StanfordUniv. Press, Stanford, Calif., 1946), p. 71.

4. G. Wilken, Am. Antiquity 26, 432 (1971). Al-though the concept of intensive Mayan agri-culture has recently received considerable at-tention, it is not new, having been suggestedas early as 1925 by T. Gann [Mystery Cities(Duckworth, London, 1925), p. 22] and laterby 0. G. and E. B. Ricketson [Carnegie Inst.Wash. Pubi. 477 (1937), p. 12].

5. Intensive agriculture is defined here as anymode of cultivation in which the frequencyof cropping per unit of land exceeds thefrequency of fallowing. Swidden is an exten-sive mode of agriculture in that the fre-quency of fallowing exceeds the frequency ofcultivation. Specific cropping techniques, labor,or productivity are not essential to the def-initions.

6. W. M. Denevan, Science 169, 647 (1970).7. E. Boserup, The Conditions of Agriciultuiral

Growth: The Economics of Agrarian Changeunder Population Pressure (Aldine, Chicago,1965).

8. H. C. Brookfield, Pac. Viewpoint 13, 30(1973).

9. W. T. Sanders, in Popzulation Growth:Anthropological Implications, B. Spooner, Ed.(MIT Press, Cambridge, Mass., 1972), p.556.

10. G. R. Willey, W. R. Bullard, J. B. Glass,J. C. Gifford, Pap. Peabody Mus. Archaeol.Ethnol. Harv. Univ. 54, 1 (1965).

11. W. R. Bullard, Am. Antiquity 25, 355 (1960).12. W. Haviland, World Archaeol. 2, 187 (1970).13. Srecific figures are difficult to calculate, as the

production of any mode of swidden cultiva-tion is dependent on varying parameters.However, S. Cook [Addison-Wesley Modular(Addison-Wesley, Reading, Mass., 1972, Publ.16)] offers subsistence data suggesting thatswidden agriculture was hard-pressed to sup-port peak Mayan populations.

14. G. R. Willey and D. Shimkin, Southwest. J.Anthropol. 27, 1 (1971); T. P. Culbert, Ed.The Classic Maya Collapse (Univ. of NewMexico Press, Albuquerque, 1973).

15. A more thorough discussion is forthcomingin B. L. Turner II, in preparation.

16. A. Palerm and E. Wolf, Social ScienceMonograph No. 3 (Pan American Union,Washington, D.C., 1957), p. 28.

17. C. L. Lundell, Southwest. Rev. 19, 65 (1933).18. K. Ruppert and J. Denison, Carnegie Inst.

Wash. Publ. 543 (1943).19. F. Blom, Irrig. Me'x. 27, 5 (1946).20. L. Ower, Geogr. J. 70, 372 (1927).21. J. E. S. Thompson, Field Mus. Nat. Hist.

Pub1. 301, Anthropol. Ser. 17, 219 (1931).22. C. L. Lundell, Carnegie Inst. Wash. Misc.

Pap. 522 (1940), pp. 9-12.23. A. Wright, D. Romney, R. Arbuckle, V. Vial,

Colonial Research Publication No. 24 (HerMajesty's Stationary Office, London, 1959).pp. 112-113.

24. A. H. Siemens and D. Puleston, Am. Antiquity37, 288 (1972); Siemans and Puleston arecurrently examining large raised-field com-plexes in the Rio Hondo floodplain and inthe bajos of northern Belize (personal com-munication).

25. See, for example, R. E. W. Adams et al.,Preliminary Reports on Archaeological Investi-

gations in the Rio Bec Area, Campeche, Mex-ico (Middle American Research Institute,Tulane Univ., New Orleans, La., in press).

26. The areal limits of Rio Bec terracing thatwere recorded are within the areas I ex-amined. J. Eaton, who has also called atten-tion to the relic terraces in the Rio Becregion (27, p. 54) has noted similar struc-tures further south and east of Xpujil (per-sonal communication).

27. J. Eaton, Ceram. Cult. Maya 8, 42 (1972).28. J. Spencer and G. Hale, Pac. Viewpoint 2,

1 (1961).29. 0. F. Cook, Natl. Geogr. Mag. 29, 474

(1916).30. J. Rowe, in The Handbook of South American

Indians, J. Steward, Ed. (Government Print-ing Office, Washington, D.C., 1947), vol. 2,p. 183.

31. R. B. Woodbury, Soc. Am. Archaeol. Men.16, 1 (1961).

32. F. Engel, Curr. Anthropol. 14, 271 (1973).33. P. M. Thomas, Jr., in (25).34. Analysis of soil samples taken fronm the Rio

Bec region are not completed. However, initialindications are that numerous soil types arerather fertile, but suffer from problems oferosion and drainage. For a similar assess-ment of Peten soils see C. S. Simmons, J.M. Tarano, J. H. Pinto, Clasificacidn deReconocimiento de los Suelos de la Republicade Guatemala (Editorial del Ministerio deEducaci6n Publica, Guatemala, 1958), and B.Olson, Agronomy Mimeograph No. 69-2 (De-partment of Agronomy, Cornell Univ., Ithaca,N.Y., 1969).

35. Similar conclusions have been suggested con-

cerning relic terraces in the Maya Mountainsby Lundell (22, p. 11) and highland Chiapasby L. Guzman [Rev. Interam. Cienc. Soc. 1,398 (1961)].

36. W. M. Denevan and B. L. Turner II, J.Trop. Geogr., in press.

37. The term "ridges" as applied to the linearwalls found in the vicinity of Becan shouldnot be confused with either terraces or raisedfields. Eaton's (27) use of the term "ridgedfields" refers to ridges that were probablynonagricultural in origin.

38. The 1973 Rio Bec permit granted to theUniversity of Texas at San Antonio-Univer-sity of Wisconsin, Madison, research groupby the Instituto Nacional de Antropologia eHistoria allowed archeological examinationonly within 30 km of Xpujil, Campeche.

39. B. Bronson, Souithwest. J. Anthropol. 22, 251(1966); also see A. Wright et al. (23, p. 111).

40. The chronological sequence was developedby J. Ball [Ceram. Ctult. Maya 8, 34 (1972)].

41. For a more detailed discussion of Rio Becceramic data and their implications, see J.Ball, thesis, University of Wisconsin, Madison(1973).

42. Ceramics were gathered from terraces andassociated housemounds on five different RioBec hillsides by J. Eaton, J. Taschek, andB. L. Turner. Ceramic analysis was conductedby J. Ball. Although the sample size issmall, ceramic data are coherent with Ball'sextensive ceramic survey (41) of Becan.

43. U. Cowgill (Am. Anthropol. 64, 273 (1962)]generously concludes (p. 277) that swiddenagriculture near Lake Peten could support 38to 77 people per square kilometer (100 to200 people per square mile).

44. R. Reina [Am. Anthropol. 69, 1 (1967)] pro-vides contradictory evidence to that gatheredby Cowgill (43) concerning the productivityof Peten cultivation.

45. I. Vogeler, in (25). The portion of Campecheinvestigated by Vogeler has only recently beenexposed to cultivation, and a full cycle hasnot been established. The cycle used tocalculate the carrying capacity figures is basedon optimistic estimates suggested by immi-grant farmers. Furthermore, Vogeler's carry-ing capacity figures may be in error. Mycalculations, using the same figures and for-mula, indicate carrying capacities of 28 to65 people per square kilometer.

46. H. C. Conklin, Proc. Ninth Pacific Sci.Assoc. 1957 7, 60 (1959). Critical populationsize, C,, is equal to LIAT, where L is themaximum cultivable land available, A is theminimum average units of land required forclearing per individual per year, and T is theminimum average duration of the full agri-cultural cycle.

47. My calculations are based on the entire per-mit area of 2827.43 square kilometers. If 75

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percent of this area is cultivable, then C =(2120.57 km2)/(1 X .005 km2), or C, = 424,145km2.

48. The term "collapse" refers to the declineand eventual abandonment of the ceremonialcenters in the southern and central lowlandsfrom A.D. 790 to 950 (see 14).

49. This theory, which is alluded to throughoutMayan literature, was perhaps first discussedby 0. F. Cook, Smithson. Inst. Annu. Rep.1919 (1921), p. 314.

50. First suggested by biologists from the Depart-ment of Agriculture, the grassland theory re-ceived considerable attention from S. G.Morley (3).

51. Terracing and raised fields are constructedthroughout the tropics by "digging stick"farmers. Perhaps most impressive are theraised-field cultivators of highland NewGuinea [see K. Heider, Viking Fund Puibl.Anthropol. 49 (1970)].

52. The Peten remains the principal central low-land region in which relics of intensive agri-culture have yet to be reported in abundance.This is, perhaps, largely the result of inade-quate field research. I noted relic terracesalong the main road from Flores to CiudadMelchor de Mencos (about 35 km southeastof Tikal) on a reconnaissance of the Pet6nin January 1974. A series of five terraces wasconstructed across a ravine which was about30 meters wide. Embankments were composedentirely of stone rubble and dirt. Informantsindicated that stone-faced terraces are com-mon on hillsides that are inland from themain road.

53. For similar assessment, see G. R. Willeyand D. Shimkin, in The Classic Maya Col-lapse, T. P. Culbert, Ed. (Univ. of New Mex-ico Press, Albuquerque, 1973).

54. A similar assessment has been adopted byT. P. Culbert [The Lost Civilization: The

Story .of the Classic Maya (Harper & Row,New York, 1974), pp. 46-49].

55. I thank R. E. W. Adams, Donald D. Brand,and William M. Denevan for criticisms andconsultation; Joseph Ball for ceramic anal-ysis; and the 1973 National Geographic So-ciety Rio Bec Project members for aiding andencouraging this research. I am indebted toGuillermo Bonfil Batalla, director general ofthe Instituto Nacional de Antropologia eHistoria (INAH), Mexico City; IgnacioMarquina, director of the Departamento deMonumentos Prehispanicos, INAH; MiquelMesmacher, former representative of the INAHin the Yucatfin archeological area; and CarlosSansores Perez, former governor of Campeche,Mexico. Financial aid was provided by theNational Science Foundation and the Ibero-American Studies Program of the Universityof Wisconsin, Madison. Maps were preparedby Bruce Van Roy.

NEWS AND COMMENT

Watergate: 1972 CampaignersTried to Use R &D Agencies

A report by the staff of the SenateWatergate committee describes in de-tail a White House plan, in 1972, tomanipulate grants, contracts, and ap-pointments throughout the government,including agencies concerned withR & D and education, to the benefit ofthose who might be friendly to theNixon campaign. The report, obtainedby Science in draft form, is a chapterof the committee's final report and isdue to be published along with thefinal report later this month. Thecommittee launched congressional in-quiry into the Watergate scandals lastyear.The White House plan was known

as the "responsiveness program," andits "chief architect" was Frederic V.Malek, then special assistant to thePresident and now deputy directorof the Office of Management andBudget (OMB). Among the agenciesto be involved in the responsivenessprogram were, according to the draftSenate report, the National ScienceFoundation (NSF), the NationalOceanic and Atmospheric Administra-tion (NOAA), the Urban Mass Trans-portation Administration (UMTA),the National Institute for Occupation-al Safety and Health (NIOSH), andsome education jobs. Other research-oriented agencies mentioned in theWhite House memorandums obtainedby the Senate committee are theNational Institute of Education (NIE)and the Consumer Product SafetyCommission (CPSC). In addition, theMalek subordinates who executed the

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responsiveness pregram wanted to havea career employee of the Equal Em-ployment Opportunity Commission(EEOC) fired after he appeared to besympathetic to Democratic candidateGeorge McGovern. But the employeestayed on, and there is scant evidencein the other instances cited in thereport that the Malek team had muchsuccess in bending the federal bu-reacracy to their aims.

Senate Watergate investigators, dur-ing the limited time they could giveto the responsiveness program in-quiry, focused on White House at-tempts to win the Spanish-speakingvote through use of grants, contracts,and appointments. These findings arethe focus of the draft report andhave already been reported in the NewYork Times. The committee, to a les-ser extent, looked into responsivenessefforts for the black vote, but the at-tempts to use the research grants andthe education appointments receive onlypassing scrutiny. Although investiga-tors found what looked like evidenceof violation of the Hatch Act and otherfederal laws in the Spanish-speakingcampaign, they did not specifically in-vestigate possible criminal activity inthese other instances. Said one staffer,"This is an area which obviously de-serves further inquiry. . . . This issomething which we hope will be in-vestigated further by other committees."The responsiveness program orig-

inated as a result of a feeling bysome White House aides that the ex-ecutive branch was being underused

as a source of help in the campaign.Typical of this sentiment was a memoby Jeb S. Magruder, then on the WhiteHouse staff, who eventually directedthe Committee for the Re-Election ofthe President (CRP). Magruder wrotethen-Attorney General John Mitchellin January 1971, according to the Sen-ate report,

[O]ur administration has not made ef-fective political use of the resources ofthe Federal government, the RNC [Re-publican National Committee], the WhiteHouse, and outside groups and corpora-tions. In developing the structure for thecampaign, proper use of these resourcesshould be of preliminary concern at theoutset of the planning.

Subsequently, Magruder, accordingto the Senate report, "at the AttorneyGeneral's request began an examina-tion of utilization of federal resourcesby others in presidential campaigns."Magruder concluded, the report says,that, while President Eisenhower didnot, President Johnson and Vice Pres-ident Humphrey did use their WhiteHouse staffs for their campaigns. PeterMillspaugh, a White House aide, urgedin May 1971 that an inventory betaken of federal resources to be used"with perhaps the federal grants areabroken out for priority treatment." Andin a 23 June 1971 memo, Millspaughincluded the NSF on his list of likelytargets.

"The Basic Types of Patronage"1) Jobs (full time, part time, retainers,

consultantships, etc.)2) Revenue

-Contracts (Federal government as pur-chaser-GSA [General Services Admin-istration])-Grants (do-good programs, EDA [Eco-nomic Development Administration], mod-el cities, NSF research, etc.)-Subsidies (needy industries-airlines,etc. )-Bank Deposits (all Federal accounts)-Social Need Programs (direct benefit tocitizens, i.e., social security, welfare, etc.)-Public Works Projects.

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