Research ArticleANTHROPOLOGY

Boiled or roasted? Bivalve cooking methods of early Puerto Ricans elucidated using clumped isotopes

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Science Advances  27 Nov 2019:
Vol. 5, no. 11, eaaw5447
DOI: 10.1126/sciadv.aaw5447
  • Fig. 1 Location figure.

    (A) Map of Puerto Rico with highlighted region. (B) Details of the highlighted region showing the Cabo Rojo National Wildlife Refuge and the location of the excavation site discussed here (CRNWR_P13). The figure was adapted from park data published by the U.S. Fish and Wildlife Service.

  • Fig. 2 Stratigraphic section of shell midden excavation site including location of radiocarbon age estimates.

  • Fig. 3 Δ47 values for uncooked modern shells and shell midden constituents from CRNWR and experimental results for cooked bivalves presented by Müller et al. (9).

    (A) Δ47 values of all modern and ancient samples measured in this study (black dots); colored regions display the probability distribution for each group of analyses. Shaded regions behind points delineate sample frequency and are generated using distributionPlot for MATLAB by J. Dorn. The location, estimated age ±2σ, and sample ID of radiocarbon measurements are shown in the bottom of the figure as stars. (B) Δ47 values (y axis) and temperature of heating (x axis) of Müller et al. (9) cooked clams. T1/2 estimates for Δ47 equilibration half-lives based on the Arrhenius model extrapolating through direct heating experiments of biogenic aragonite between 125° and 175°C (10). The secondary y axis for both figures is estimated maximum cooking temperature.

  • Table 1 Average δ13C, δ18O, and Δ47 values for all 30 sample materials.

    Uncertainty corresponds to ±1 SD from replicate analyses. Inferred paleotemperatures were calculated from Δ47 values using the calibration from Staudigel et al. (25). ARF, absolute reference frame; VPDB, Vienna PDB.

    δ13Cδ18OΔ47Inferred
    paleotemperature
    Sample groupIDN(‰VPDB)±(‰VPDB)±(‰ARF)±(°C)
    CR_ModernA23.5580.052−0.1260.0920.6730.00432.7
    CR_ModernB1−2.7750.1660.69226.1
    CR_ModernC1−2.9110.2800.67532.0
    CR_ModernD2−3.1960.0250.3070.1300.6870.00027.8
    CR_ModernE14.708−0.4480.70123.2
    CR_ModernF11.7300.7100.69425.4
    CRNWR_P13 (shell midden) samples
    Level 1.1A13.413−0.0970.68727.8
    Level 1.1B12.954−0.4310.68727.8
    Level 1.1C12.8660.1950.68129.8
    Level 1.1D24.2440.033−0.5700.0120.5980.04763.3
    Level 1.1E24.4120.021−0.4290.0440.5970.00864.1
    Level 1.1F24.2410.069−0.0770.0310.6390.01045.3
    Level 1.2A23.1230.0790.0620.0670.7040.01922.1
    Level 1.2B13.6790.0610.66037.2
    Level 1.2C23.7760.005−0.7480.0490.5070.044117.6
    Level 1.2D14.029−0.3950.67930.5
    Level 1.2E23.4940.0070.0840.0830.6390.00145.6
    Level 1.2F23.2340.1520.1130.0750.5730.02776.0
    Level 1.3A22.3780.0910.1680.1430.6200.01953.5
    Level 1.3B21.8720.011−0.2360.0060.5610.02282.4
    Level 1.3C23.4560.0710.0300.0280.6890.00727.1
    Level 1.3D24.0200.039−0.2120.0080.6890.00627.1
    Level 1.3E13.3660.1470.68827.4
    Level 1.3F13.0390.0330.68528.2
    Level 1.4A23.2730.022−0.0280.0850.7060.02621.3
    Level 1.4B21.6450.040−0.4820.0280.6340.00547.7
    Level 1.4C23.2900.002−0.0280.0140.5440.02192.7
    Level 1.4D24.2600.034−0.5160.0010.5860.00469.3
    Level 1.4E24.0840.013−0.4950.0480.6570.00338.4
    Level 1.4F13.9740.1780.67232.9

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/11/eaaw5447/DC1

    Supplementary discussion on quantifying mineralogy using XRD

    Table S1. XRD peak areas for calcite [104] (Acalc) and aragonite [111] (Aarag) of calibration materials and bivalves from the CRNWR excavation site.

    Fig. S1. XRD scans of pure aragonite and calcite.

    Fig. S2. Relative peak area for aragonite and calcite relative to the molar fraction of each mineral.

    Fig. S3. Photographs of all shells analyzed in this study.

    Fig. S4. Cross plot of δ13C and δ18O values for all modern and shell midden bivalves discussed in the main text.

    Data S1. Isotopic analyses of equilibrated gases, Cabo Rojo bivalves, and ETH carbonate standards.

  • Supplementary Materials

    The PDFset includes:

    • Supplementary discussion on quantifying mineralogy using XRD
    • Table S1. XRD peak areas for calcite 104 (Acalc) and aragonite 111 (Aarag) of calibration materials and bivalves from the CRNWR excavation site.
    • Fig. S1. XRD scans of pure aragonite and calcite.
    • Fig. S2. Relative peak area for aragonite and calcite relative to the molar fraction of each mineral.
    • Fig. S3. Photographs of all shells analyzed in this study.
    • Fig. S4. Cross plot of δ13C and δ18O values for all modern and shell midden bivalves discussed in the main text.
    • Legend for data S1

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    Other Supplementary Material for this manuscript includes the following:

    • Data S1 (Microsoft Excel format). Isotopic analyses of equilibrated gases, Cabo Rojo bivalves, and ETH carbonate standards.

    Files in this Data Supplement:

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