Research Article

Ancient lowland Maya complexity as revealed by airborne laser scanning of northern Guatemala

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Science  28 Sep 2018:
Vol. 361, Issue 6409, eaau0137
DOI: 10.1126/science.aau0137
  • Representation of the archaeological site of Naachtun, Petén, at twilight.

    Each ancient structure is marked by a yellow dot.

    CREDIT: L. AULD-THOMAS AND M. A. CANUTO
  • Fig. 1 Distribution of 12 PLI survey blocks.

    Location of 12 PLI survey blocks in relation to the central Maya Lowlands area as well as to the sites mentioned in text; for those survey blocks without a named site, the name of the block is provided (i.e., Env 1, Env 2, and Yala).

  • Fig. 2 Close-up of Xmakabatun.

    Image of Xmakabatun that demonstrates the high-fidelity detail of the Teledyne Opech Titan sensor. (A) Looting depressions highlighted by an openness visualization. (B) Looting features as drawn in the field (shown in red) as well as evidence of monumental architecture, causeways, residential structures, ditches, and terraces.

  • Fig. 3 Mapped areas within PLI zone.

    Map of survey blocks showing (i) areas covered by pedestrian surveys before acquisition of lidar data and (ii) areas where ground verification of the lidar data has been completed to date.

  • Fig. 4 Visualizations used for lidar analysis.

    (A) Red Relief Image Map (RRIM); (B) Sky-View Factor (SVF); (C) Simple Local Relief Model (SLRM); (D) Prismatic Openness.

  • Fig. 5 Wetland and upland agricultural features.

    Examples of intensive wetland fields featuring networks of canals (above) and upland field zones featuring low stone wall features and terraces.

  • Fig. 6 Agricultural features relative to population densities.

    Map of survey blocks showing deviations from expected density of upland field areas relative to settlement density class area. Expected (i.e., “no difference”) value is 1.0.

  • Fig. 7 Settlement density patterns.

    Density values are expressed as structures/km2.

  • Fig. 8 Cluster analysis of density patterns.

    Ward linkage method, squared Euclidean distance.

  • Fig. 9 Map of survey blocks showing causeway density patterns.

    Causeways are shown in white; values represent cumulative causeway length (in meters) normalized by survey block area (km2).

  • Fig. 10 Density of defensive features.

    Density is expressed as linear meters of defensive features per square kilometer normalized by survey block area.

  • Table 1 Lidar ground point averages.

    Important archaeological sites and lidar ground point densities within each PLI polygon.

    PolygonSurvey blockMain archaeological
    site(s)
    Area (km2)Lidar returns:
    Total points
    Lidar returns:
    Ground points
    Ground points/m2
    1601HolmulHolmul308.648,294,456,212310,174,1741.11
    Xmakabatun
    1602XultunXultun124.023,427,027,990138,067,3831.13
    San Bartolo
    1603TikalTikal146.9314,614,355,752926,848,5732.07
    UaxactunUaxactun163
    ZotzEl Zotz143.73
    1604NaachtunNaachtun135.293,666,496,941197,825,1811.48
    1605TintalTintal97.053,118,138,624184,909,3241.94
    1606CoronaLa Corona431.6712,388,384,3521,144,897,0432.72
    El Achiotal
    1607Yala172.274,495,443,060331,572,4411.95
    1608PerúEl Perú-Waka’91.272,302,198,44097,224,3971.09
    1609Env 2145.663,599,229,811868,902,2795.17
    1610Env 1184.284,147,724,212971,717,5255.32
    Total2,143.8160,053,455,3945,172,138,3202.45
  • Table 2 Lidar visualizations.

    Raster visualization combinations created and used for feature identifications.

    Terrain visualizationRaster comboColor ramp/band comboTransparencyUtilityNotes
    Simple Local Relief
    Model (SLRM)
    Very small buildings,
    slight depressions,
    agricultural features
    Layer 1SLRMBlack to white0%Created in Relief Visualization
    Toolbox (RVT) (30)
    Modified Red Relief
    Image Map (RRIM)
    Small buildings,
    depressions,
    contour terraces
    Based on procedures
    detailed in (31)
    Layer 1SlopeCustom: white to red0% Created in ArcToolbox Slope;
    visualized in QGIS with
    blending mode “multiply”
    Layer 2SLRMCustom:
    blue-gray-yellow
    0% Created in RVT (30)
    Sky-View Factor (SVF) Depressions,
    orthogonal buildings
    Layer 1SVFBlack to white0% Created in RVT (30, 32)
    Prismatic Openness Small buildings,
    agricultural features
    “Openness” (33)
    Layer 1Positive opennessWhite to black50% Created in RVT (30)
    Layer 2Negative opennessBlack to white50% Created in RVT (30)
    Layer 316-dir. hillshadeRGB: 3,2,10% Created in RVT (30) with
    vertical exaggeration of 3–5
  • Table 3 Extent mapping and ground verification.

    Areas in the PLI survey region covered by both pre-lidar pedestrian surveys and post-lidar ground validation efforts (these sometimes overlap).

    SiteArea (km2)Pre-lidar
    pedestrian
    survey (km2)
    Used by PLI
    Pre-lidar
    pedestrian
    survey (km2)
    Post-lidar ground
    validation (km2)
    Combined sampled
    area (km2)
    Corona4322.02.06.96.9
    Env 11840.00.00.00.0
    Env 21460.00.00.00.0
    Holmul30946.037.016.350.8
    Naachtun1357.97.97.715.6
    Perú918.28.221.629.8
    Tikal14786.216.30.016.3
    Tintal972.82.81.03.8
    Uaxactun16321.421.40.521.9
    Xultun1244.64.60.04.6
    Yala1720.040.00.00.0
    Zotz1443.13.116.016.0
    Total2144182.2103.270.0165.6
  • Table 4 Total structures and settlement density estimates by PLI survey blocks.
    NameArea (km2)StructuresStructures/km2
    Corona4323,6298
    Env 11843072
    Env 21462542
    Holmul3097,20723
    Naachtun13511,97989
    Perú914,09645
    Tikal14712,34184
    Tintal974,13043
    Uaxactun1635,07531
    Xultun1245,51344
    Yala1727404
    Zotz1446,25444
    Total2,14461,48029
  • Table 5 PopIndex calculations.

    Set of adjustments used to calculate a “population index” (PopIndex), which produces an estimated population when multiplied by structure number. The range in the value of each adjustment indicates the variation within the published record.

    AdjustmentMinLowMiddleHighMax
    1. Invisible or hidden structures110%110%110%110%110%
    2. Contemporaneity of occupation75%80%83%87%90%
    3. Residential structures75%80%81.1%83.5%85.7%
    4. Late Classic80%83%87.5%92%95%
    5. Persons per structure4.004.374.895.405.60
    PopIndex (for Late Classic)1.982.553.163.974.51
  • Table 6 Maximum sustainable population of each survey block.

    Calculations designed to determine the maximum sustainable population within each survey block based on (i) its total measured agricultural area (values adjusted for Late Classic contemporaneity using AgroIndex) and (ii) a minimum swidden area of 0.48 ha/person (mean value of range reported in table S3).

    Survey blockUplands
    (ha)
    Wetlands
    (adj. ha)
    Modified uplands
    (adj. ha)
    Pop. capacity
    (0.48 ha/person)
    Population
    (PopIndex 3.16)
    Under/over
    capacity
    % capacity
    Naachtun3,3872,2882,57417,06237,88920,827222%
    Tikal6,0694074,30522,29838,89216,594174%
    Xultun1,99202,84710,00817,4387,430174%
    Perú3,89203518,77712,9564,179148%
    Tintal5,40938074613,51613,063–45397%
    Uaxactun4,2382813,95817,53216,052–1,48092%
    Zotz11,485799424,11219,781–4,33182%
    Holmul12,8661,3502,32234,20622,796–11,41067%
    Corona19,39901440,15011,478–28,67129%
    Yala7,73808216,1722,341–13,83114%
    Env 18,243013017,319971–16,3476%
    Env 210,487524421,887803–21,0844%
    PLI survey area95,2054,83617,468243,039194,460–48,5790%
  • Table 7 Correlation of upland agricultural features with settlement density.

    Correlation matrix of intensive agriculture upland field zones and settlement density zones in m2 (upland zones strongly correlate with periurban and urban zones; N = 12).

    VacantRuralPeriurbanUrbanUrban
    core
    Intensive
    agr. fields
    VacantPearson correlation10.612*–0.368–0.381–0.460–0.289
    Significance (two-tailed) 0.0340.2390.2210.1330.361
    RuralPearson correlation0.612*10.278–0.021–0.1520.248
    Significance (two-tailed)0.034 0.3820.9490.6370.438
    PeriurbanPearson correlation–0.3680.27810.835**0.694*0.749**
    Significance (two-tailed)0.2390.382 0.0010.0120.005
    UrbanPearson correlation–0.381–0.0210.835**10.775**0.645*
    Significance (two-tailed)0.2210.9490.001 0.0030.023
    Urban corePearson correlation–0.460–0.1520.694*0.775**10.505
    Significance (two-tailed)0.1330.6370.0120.003 0.094
    Upland areaPearson correlation–0.2890.2480.749**0.645*0.5051
    Significance (two-tailed)0.3610.4380.0050.0230.094

    *Correlation is significant at the 0.05 level (two-tailed). **Correlation is significant at the 0.01 level (two-tailed).

    • Table 8 Late Classic structure density classes, modified from Rice and Culbert (35).
      PLI density classSite centersSite peripheriesRural
      ClassDensitySiteArea (km2)DensitySiteArea (km2)DensityRegionDensity
      Urban core300+Caracol2.2300
      Tikal9235
      Urban150–300Ceibal1.6222
      Becan3171Tikal (16 km)7181
      Tayasal2.5128Ceibal13.6116Belize Valley116
      Periurban60–150Cenote0.5128
      Uaxactun16106
      Tikal/Yaxha60
      Nohmul458 Lakes Macanche-Salpeten57
      Lakes Yaxha-Sacnab47
      Rural<60 Lakes Quexil-Petenxil36
      Tikal (survey strips)39
      Uaxactun30
      Nohmul12
      Vacant≤10
    • Table 9 Relative frequency of structures in each density class by PLI survey block.

      NameRuralPeriurbanUrbanUrban core
      Corona81%14%5%0%
      Env 1100%0%0%0%
      Env 2100%0%0%0%
      Holmul43%48%8%0%
      Naachtun13%41%36%10%
      Perú35%24%6%34%
      Tikal12%49%25%14%
      Tintal28%48%11%12%
      Uaxactun46%47%7%0%
      Xultun25%42%25%7%
      Yala100%0%0%0%
      Zotz36%54%11%0%
      All30%43%18%9%
    • Table 10 Defensive data for individual defended areas.

      Summary of defensive data for individual defended areas and perimeter statistics. Bold lines separate different lidar survey blocks (in order as Yala, Tikal, Uaxactun, Holmul, Zotz, Xultun, Perú, Corona, and Tintal).

      Site/regionDefended areaNumber of
      defensive
      features
      Number of
      defensive
      systems
      Area
      (ha)
      Length of
      all built
      defenses
      (m)
      Total
      perimeter
      length
      (m)
      Length of
      built perimeter
      defenses
      (m)
      Length of
      natural
      perimeter
      defenses (m)
      Total length
      of perimeter
      defenses
      (m)
      % of perimeter
      with built
      defenses
      % of perimeter
      with natural
      defenses
      % of total
      perimeter
      defended
      E4 River SiteSite core447.57271,1707274431,17062%38%100%
      Tikal*City extent1391010,677.418,60315,67512,0723,41815,49077%22%99%
      Tikal PolityGroup NW of
      Tikal Wall
      6270.41,0273,6709002,7633,66325%75%100%
      AtalayaAtalaya core2113.61981,9961981,7871,98510%90%99%
      RS028Refuge213.213276413263176417%83%100%
      RS07Eastern hilltop221.74525394528753984%16%100%
      CivalCival core5328.21,0801,9741,0803611,44155%18%73%
      Dos AguadasDos Aguadas
      North E plateau
      2211.41,8251,6371,625131,63799%1%100%
      Dos AguadasDos Aguadas
      North N plateau
      3123.21,3412,1605281,5852,11324%73%98%
      Dos AguadasDos Aguadas
      North W plateau
      117.86541,3636547081,36348%52%100%
      Dos AguadasDos Aguadas
      South core
      14752.13,3913,6601,6501,8613,51145%51%96%
      Dos Aguadas*Dos Aguadas
      South macro
      74162.02,2434,3492,2438043,04752%18%70%
      KanalnaKanalna N refuge217.12871,2801161,1641,2809%91%100%
      KanalnaKanalna S refuge1116.72182,5842182,3442,5638%91%99%
      La SufricayaLa Sufricaya core439.65561,2045569665246%8%54%
      Turca†Turca core1199
      TurcaTurca E refuge212.827169514854769521%79%100%
      WitznaWitzna core3144.05474,2542003,0113,2115%71%75%
      Witzna EastWitzna East10414.19422,0666301,3902,02031%67%98%
      Xmakabatun
      Polity
      Summit E
      of drainage
      642.988174641218159455%24%80%
      Xmakabatun
      Polity
      Summit W of
      drainage
      115.452592452521373857%23%80%
      El ZotzEl Diablo15421.63,3472,4031,8294712,30076%20%96%
      El ZotzEl Tejon1139.31,7171,3995428051,34639%58%96%
      El ZotzHill NW of El Diablo
      Group
      510.933248014833248031%69%100%
      El Zotz Polity‡Drainage N of
      La Cuernavilla
      6110.44371,106
      El Zotz PolityHills at N drainage
      intersection
      3215.37711,9667711,1911,96239%61%100%
      El Zotz PolityHills W of
      La Cuernavilla
      7311.51,0352,9046022,2932,89521%79%100%
      La CuernavillaLa Cuernavilla East27655.05,0144,2221,2781,7773,05530%42%72%
      La CuernavillaLa Cuernavilla West24321.74,2622,6971,7777222,49966%27%93%
      Xultun Polity‡City extent211298
      Xultun Polity‡Unknown21332
      El Perú-Waka’El Perú-Waka’
      core
      32164.11,1005,1931,1002,1513,25121%41%63%
      El Perú-Waka’
      Polity‡
      Territorial extent111,240
      El Achiotal PolityDefensive enclosure1011.8827522505050597%0%97%
      El Achiotal PolityPeninsula refuge3116.75542,1933541,7922,14516%82%98%
      TintalTintal core15337.32,7032,4811,8114522,26373%18%91%

      *The defended area extends beyond the limits of the lidar data, but a substantial portion is visible. All statistics are based on the visible perimeter and area, but may not be reliable metrics of the actual defended area.

      †There is no clearly discernible defended area for the defensive systems present. Area not included in comparative analyses.

      ‡The defended area extends beyond the limits of the lidar data and is too incomplete to include in comparative analyses.

      • Table 11 Statistics for reinforcing defenses.

        Bold lines define natural breaks (Jenks) in the percentages of additional defenses in relation to an area’s perimeter.

        Site/regionDefended areaLength of additional
        defenses (m)
        % of additional
        defenses from
        total built
        % of additional
        defenses from total
        perimeter
        La CuernavillaLa Cuernavilla East373675%122%
        La CuernavillaLa Cuernavilla West248558%99%
        El ZotzEl Tejon117668%87%
        TintalTintal core181167%80%
        Xmakabatun PolitySummit E of drainage46953%79%
        El ZotzEl Diablo151945%66%
        El Achiotal PolityDefensive enclosure32139%64%
        Dos AguadasDos Aguadas South core174251%50%
        Tikal*City extent653135%42%
        Dos AguadasDos Aguadas North N plateau81361%38%
        El ZotzHill NW of El Diablo Group18455%38%
        TurcaTurca E refuge12345%18%
        Witzna EastWitzna East31233%15%
        El Zotz PolityHills W of La Cuernavilla43342%15%
        KanalnaKanalna N refuge17160%13%
        Dos AguadasDos Aguadas North E plateau20011%12%
        WitznaWitzna core34763%11%
        El Achiotal PolityPeninsula refuge20036%9%
        Tikal PolityGroup NW of Tikal Wall12712%3%
        RS028Refuge00%0%
        Dos AguadasDos Aguadas North W plateau00%0%
        RS07Eastern hilltop00%0%
        E4 River SiteSite core00%0%
        El Zotz PolityHills at N drainage intersection00%0%
        AtalayaAtalaya core00%0%
        KanalnaKanalna S refuge00%0%
        Xmakabatun PolitySummit W of drainage00%0%
        CivalCival core00%0%
        Dos Aguadas*Dos Aguadas South macro00%0%
        El Perú-Waka’El Perú-Waka’ core00%0%
        La SufricayaLa Sufricaya core00%0%

        *The defended area extends beyond the limits of the lidar data, but a substantial portion is visible.

        • Table 12 Degree of preparedness for each defended area.

          The degree to which the need for defense was anticipated at the time of initial settlement. Scores closer to 0 indicate minimal preparedness.

          Site/regionDefended areaPreparedness index
          El ZotzHill NW of El Diablo Group369
          RS028Refuge199
          El Zotz PolityHills W of La Cuernavilla199
          TurcaTurca E refuge194
          KanalnaKanalna N refuge164
          KanalnaKanalna S refuge140
          AtalayaAtalaya core132
          El Achiotal PolityPeninsula refuge107
          Witzna EastWitzna East99
          Dos AguadasDos Aguadas North W plateau91
          El ZotzEl Tejon87
          El Zotz PolityHills at N drainage intersection78
          WitznaWitzna core68
          Dos AguadasDos Aguadas North N plateau68
          Xmakabatun PolitySummit E of drainage62
          E4 River SiteSite core59
          RS07Eastern hilltop50
          Xmakabatun PolitySummit W of drainage39
          Tikal PolityGroup NW of Tikal Wall39
          Dos AguadasDos Aguadas South core36
          La CuernavillaLa Cuernavilla West33
          La CuernavillaLa Cuernavilla East32
          El ZotzEl Diablo22
          El Perú-Waka’El Perú-Waka’ core13
          CivalCival core13
          TintalTintal core12
          La SufricayaLa Sufricaya core10
          Dos Aguadas*Dos Aguadas South macro5
          Dos AguadasDos Aguadas North E plateau1
          Tikal*City extent0
          El Achiotal PolityDefensive enclosure0

          *The defended area extends beyond the limits of the lidar data, but a substantial portion is visible.

          • Table 13 Cost index for each defended area.

            Cost statistics for defending areas in relation to idealized forms.

            Site/regionDefended areaTotal built defenses (m)z-score of TBDOverbuild scoreEfficiency scoreCost index
            La CuernavillaLa Cuernavilla West4,2620.732.580.613.08
            La CuernavillaLa Cuernavilla East5,0140.961.910.622.94
            El ZotzEl Diablo3,3480.452.030.691.34
            Tikal*City extent18,6035.090.512.341.11
            Dos AguadasDos Aguadas South core3,3910.471.330.700.88
            TintalTintal core2,7030.261.250.870.37
            Dos Aguadas*Dos Aguadas South macro2,2430.120.501.040.06
            Dos AguadasDos Aguadas North E plateau1,825–0.011.520.73–0.02
            El Perú-Waka’El Perú-Waka’ core1,100–0.230.240.87–0.06
            El ZotzEl Tejon1,717–0.041.590.77–0.09
            Tikal PolityGroup NW of Tikal Wall1,027–0.250.350.81–0.11
            AtalayaAtalaya core198–0.500.150.65–0.12
            RS028Refuge132–0.520.210.83–0.13
            KanalnaKanalna S refuge218–0.500.150.56–0.13
            CivalCival Core1,080–0.240.570.95–0.14
            Dos AguadasDos Aguadas North N plateau1,341–0.160.780.79–0.16
            WitznaWitzna core547–0.400.230.55–0.17
            KanalnaKanalna N refuge287–0.480.300.74–0.20
            La SufricayaLa Sufricaya core556–0.400.510.91–0.22
            El Achiotal PolityPeninsula refuge554–0.400.380.66–0.23
            TurcaTurca E refuge271–0.480.450.86–0.26
            El Zotz PolityHills at N drainage intersection771–0.330.560.71–0.26
            Xmakabatun PolitySummit W of drainage525–0.400.640.89–0.29
            Witzna EastWitzna East942–0.280.710.64–0.31
            E4 River SiteSite core727–0.340.750.83–0.31
            Dos AguadasDos Aguadas North W plateau654–0.370.660.73–0.33
            RS07Eastern hilltop452–0.430.970.86–0.48
            El Zotz PolityHills W of La Cuernavilla1,035–0.250.860.41–0.52
            Xmakabatun PolitySummit E of drainage881–0.301.460.81–0.53
            El Achiotal PolityDefensive enclosure827–0.311.730.91–0.59
            El ZotzHill NW of El Diablo Group332–0.460.990.70–0.65

            *The defended area extends beyond limits of lidar data, but a substantial portion is visible.

            • Table 14 Regional defensive statistics by lidar survey block.

              TLD, total length defended; TBD, total built defenses.

              PolygonMajor
              site
              Lidar
              area
              (km2)
              Number of
              defensive
              systems
              km2 of
              lidar per
              defensive
              system
              Number of
              defensive
              features
              km2 of
              lidar per
              defensive
              feature
              Total length
              of defended
              perimeters
              (m)
              Length of
              defended
              perimeter per
              km2 of lidar
              Defended
              area
              (km2)
              % lidar
              area
              defended
              TLD
              (m)
              TLD per
              km2
              of lidar
              TBD
              length
              (m)
              TBD per
              km2 of
              lidar
              E1184.1400.000.0000.00.0%00.000.0
              E2145.5900.000.0000.00.0%00.000.0
              E4172.02443.0443.01,17070.10.0%1,1706.87274.2
              1Tikal161.331213.41451.119,345120107.566.6%25,811160.019,630121.7
              2Uaxactun164.94441.2627.53,298200.20.1%3,28719.97824.7
              8Naachtun135.2600.000.0000.00.0%00.000.0
              9Holmul308.66358.8625.028,895943.91.3%29,13994.414,86248.1
              10El Zotz127.20235.5981.317,9221411.51.1%24,507192.716,915133.0
              11Xultun124.02262.0235.4000.00.0%6305.16305.1
              12El Perú90.96330.3422.75,193571.61.8%4,49149.42,34025.7
              13La Corona424.692212.31332.72,71560.20.0%3,1737.51,3813.3
              15Tintal97.03332.3156.52,481260.40.4%3,15532.52,70327.9
              Total2,135.848824.33705.881,01938115.35.4%95,36344.659,97128.1
              Average177.997.3337.430.8312.16,752399.66.0%7,94747.44,99831.1

            Supplementary Materials

            • Ancient lowland Maya complexity as revealed by airborne laser scanning of northern Guatemala

              Marcello A. Canuto, Francisco Estrada-Belli, Thomas G. Garrison, Stephen D. Houston, Mary Jane Acuña, Milan Kováč, Damien Marken, Philippe Nondédéo, Luke Auld-Thomas, Cyril Castanet, David Chatelain, Carlos R. Chiriboga, Tomáš Drápela, Tibor Lieskovský, Alexandre Tokovinine, Antolín Velasquez, Juan C. Fernández-Díaz, Ramesh Shrestha

              Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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