The Maya formed a prime relationship with wetlands, but the dynamic of Maya engagement varied by place and time largely due to environmental change. Ground truthing each locale remains essential.

We and our research team have conducted archaeological investigations along the lower courses of the Hondo and New Rivers of northern Belize (Pohl et al. 1996). The key to our project’s success lies in our geoarchaeological strategy of combining paleoecological coring with excavation pits extending below the water level using a sophisticated pumping system. The pits have filled in data on material culture extending far back into the Preclassic and Archaic periods and have yielded valuable organic remains for radiocarbon dating.    

When agriculture first appeared in northern Belize remains an open question. Paleoecological data, including pollen, have inherent weaknesses in identifying the onset of cultivation. Palynologist John Jones identified a small, archaic type of domesticated maize appearing about 3400 BCE at Cob Swamp. Our pollen diagram for Pulltrouser Swamp shows forest disturbance as early as about 5000 BCE but without definitive evidence for cultigens.

We speculate that migration played a role in changes in subsistence as documented in southern Belize (Kennett et al. 2022).  Genetic evidence from burials points to a south to north migration from Central and northern South America sometime between about 5300 BCE and 3600 BCE. Chibchan speaking migrants likely brought maize they had genetically modified (Kistler et al. 2018). This in-migration phenomenon may have impacted indigenous populations living along the Hondo and New rivers of northern Belize during this same time frame.  

Our cores recorded a dramatic expansion of human activity after about 2500 BCE. Pollen markers include a sharp decline in forest taxa such as Moraceae, charcoal from burning, appearance of weedy species, and cultigens including both maize and manioc.

The onset of drought conditions apparent in our stratigraphy, especially after 2200 BCE, would have influenced food strategies, especially in wetlands. Rich organic soils that originally formed along river margins and in karst depressions in response to late Holocene sea level rise were exposed as groundwater levels fell, providing an attractive resource for farmers. The Maya initially cultivated their crops on the wetland margins in the Late Archaic to Early Preclassic periods. Only much later did we identify evidence of ditching when water levels began to rise.

Water levels continued to rise due to sea level change, and by the Classic Period the wetlands along the lower courses of the Hondo and New rivers were mostly flooded. Near the end of the Classic Period a layer of sediment, often referred to as “Maya Clay” and resulting from soil mismanagement and erosion, filled the river margins and karst depressions. This Maya Clay, and the underlying Preclassic organic soils, are riddled with secondary gypsum, which precipitated in situ from sulfate-rich groundwater, confirming that the precipitation occurred after the Maya Clay was deposited. For this to happen, water levels had to have dropped significantly, exposing the sediments and organic soils to seasonal drying, an event we correlate with the Terminal Classic megadrought. 

None of our excavations produced evidence of wetland field construction.  Preclassic period ditching of the organic soils was detected in a few locations, at Douglas, San Antonio, Lagarto, and to a lesser extent Cob and possibly Pat, probably in response to rising groundwater. Our trenches into what appeared at the surface to be raised platforms and adjacent canals (including at Pulltrouser Swamp) turned out to be natural features created by in situ gypsum precipitation that expanded the volume of the soil more than 50%, heaving the surface upward and leaving troughs between heaved sections. The high levels of gypsum in these soils precluded maize cultivation.

In sum, the Maya pioneered wetland agriculture along the lower courses of rivers in northern Belize. Faced with environmental challenges, they attempted to rescue their fields from flooding with ditching beginning in the Late Preclassic period. The Maya eventually abandoned most wetland fields here by the Classic Period when natural processes of flooding and drought created an unstable environment. It is possible, even likely, that much of the patterned ground found today in Maya wetlands where groundwater has high concentrations of sulfate is a result of the Maya megadrought rather than Maya wetland engineering.

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Cited references

Kennett, Douglas J., Mark Lipson, Keith M. Prufer, David Mora-Marín, Richard J. George, Nadin Rohland, Mark Robinson, Willa R. Trask, Heather H. J. Edgar, Ethan C. Hill, Erin E. Ray, Paige Lynch, Emily Moes, Lexi O’Donnell, Thomas K. Harper, Emily J. Kate, Josue Ramos, John Morris, Said M. Gutierrez, Timothy M. Ryan, Brendan J. Culleton, Jaime J. Awe, and David Reich
 2022    South-to-north migration preceded the advent of intensive farming in the Maya region. Nature Communications 13(1):1530. DOI:10.1038/s41467-022-29158-y.

Kistler, Logan, S. Yoshi Maezumi, Jonas Gregorio de Souza, Natalia A. S. Przelomska, Flaviane Malaquias Costa, Oliver Smith, Hope Loiselle, Jazmín Ramos-Madrigal, Nathan Wales, Eduardo Rivail Ribeiro, Ryan R. Morrison, Claudia Grimaldo, Andre P. Prous, Bernardo Arriaza, M. Thomas P. Gilbert, Fabio de Oliveira Freitas, and Robin G. Allaby
 2018    Multiproxy evidence highlights a complex evolutionary legacy of maize in South America. Science 362(6420):1309–1313. DOI:10.1126/science.aav0207.

Pohl, Mary E. D., Kevin O. Pope, John G. Jones, John S. Jacob, Dolores R. Piperno, Susan D. deFrance, David L. Lentz, John A. Gifford, Maria E. Danforth, and J. Kathryn Josserand
 1996    Early Agriculture in the Maya Lowlands. Latin American Antiquity 7(4):372. DOI:10/d83tks.

Turner, B.L. II and Peter D. Harrison, eds.
1983 Pulltrouser Swamp. Ancient Maya habitat, agriculture, and settlement in northern Belize.  University of Texas Press, Austin.

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