Epiclassic and Early Postclassic Settlement in the Teotihuacan Valley

Changes are apparent in the distribution of Coyotlatelco and Mazapa phase ceramics (Table 1) within the prehispanic city, based on George Cowgill’s maps (Reference Cowgill2015), as well as beyond the limits of the Classic period urban center. A decrease in the number of settlements and their distribution within the subareas, as recognized by the Teotihuacan Valley Project, followed the demise of Teotihuacan´s hegemony and the subsequent Coyotlatelco and Mazapa phases (Gorenflo and Sanders Reference Gorenflo and Sanders2007). These data emphasize, however, that neither the center nor the surrounding valley was totally abandoned at this time. Although their inhabitants are assumed to have continued to cultivate accessible lands within the surrounding alluvial plain, little is known about their subsistence procurement, production, and plant use during this period.

Table 1. Prehispanic Occupation and Associated Ceramic Phases in the Teotihuacan Valley.

Inhabitants of the quarry tunnels occupied a unique setting: they lived in cave-like conditions that offered shelter but also had ritual significance (Manzanilla Reference Manzanilla and Linda2023:31–38; Manzanilla et al. Reference Manzanilla, López and Freter1996). However, these spaces are not caves in a strict geological sense but were created by the extraction of volcanic scoria (tezontle), which was used in the construction of the Classic period city. Archaeological evidence such as storage structures (“silos”), hearths, and interments, together with studies of plant and faunal remains and pollen, indicates a considerable range of domestic and ritual activities (McClung de Tapia, Martínez-Yrizar, et al. Reference de Tapia, Emily, Ibarra-Morales, Cristina Adriano-Morán, Herrera-Escobar and Linda2023). Taxa recovered from macrobotanical analyses were similar overall to the remains reported from previous excavations carried out in the Classic period urban center (González et al. Reference González, Ibarra-Morales, Zurita-Noguera, McClung de Tapia, Tapia-Recillas and Linda1993; McClung de Tapia Reference McClung de Tapia, de Tapia and Rattray1987), Late Postclassic Otumba (McClung de Tapia and Aguilar Hernández Reference McClung de Tapia and Aguilar-Hernández2001), and Cihuatecpan (Evans Reference Evans1988). The tunnels’ microenvironment favored preservation of charred and uncharred materials such as seeds in comparison with those found in extensive excavations and test pits elsewhere in the valley.

Macro- and microbotanical remains were recovered from quarry tunnels designated as Cueva de las Varillas and Cueva del Pirul (Figure 1). Both provided relatively intact occupation sequences with similar activity areas: circular bases of possible storage structures (referred to as “silos”), hearths, burials, ceramic concentrations, and other features consisting mainly of ceramic and lithic debris, ash, and contents of selected ceramic vessels. More than 1,680 sediment samples recovered during excavations provided macrobotanical evidence, including occasional in situ finds, pollen, and phytoliths (not considered in this analysis). Samples were analyzed in the Laboratorio de Paleoetnobotánica y Paleoambiente (LPP) of the Universidad Nacional Autónoma de México (UNAM) between 1994 and 1997 (Supplementary Text 1). This summary of plant remains is focused on results from activity areas identified as possible storage installations in the two tunnels pertaining to the Coyotlatelco and Mazapa phases and reused during the Aztec occupation, as confirmed by both ceramic materials and ¹⁴C determinations (Beramendi-Orosco and González-Hernández Reference Beramendi-Orosco, González-Hernández and Linda2023; Manzanilla et al. Reference Manzanilla, López and Freter1996).

Figure 1. Location of quarry tunnels east of the of the Sun Pyramid, Teotihuacan.

Charred and uncharred seeds and other macrobotanical materials indicate cultivated food resources, including Zea mays (maize), Phaseolus sp. (beans), and Opuntia spp. (nopal, tuna). The macrobotanical and pollen taxa recovered from the tunnels are summarized in Table 2 and compared in Supplementary Table 1. The archaeological contexts, particularly the circular bases of storage structures (silos), reflect diverse activities corresponding to the three occupations. The silos were possibly used initially for grain storage during the Coyotlatelco and Mazapa phases and appear to have been reused as refuse deposits during the subsequent but less extensive Aztec occupation (Supplementary Table 2). Additional plant taxa preserved throughout the occupation sequence include Portulaca oleracea (purslane), Jaltomata procumbens (jaltomate), Salvia sp. (chia), Amaranthus sp. (amaranth), and Chenopodium sp. (chenopod), suggesting that edible plants were possibly gathered or cultivated in some cases. These taxa are opportunistic plants that adapt easily to disturbed conditions, as found in paths, field margins, or other clearings. Furthermore, amaranth and chenopods are present in the pollen samples in low numbers; they are designated as “cheno-ams” because these two taxa are generally indistinguishable in archaeological pollen (Figures 2–4).

Figure 2. (a) Amaranthus sp. (4×) CV C2, N33- E96, layer 1j, Burial 3; (b) Chenopodium sp. (1×) CV C3, N33- E76, level R4, AA100; (c) cheno-am pollen (100×) CV C2, N344-E96, AA148. (Color online)

Figure 3. (a) Zea mays cob fragment. CV C2, N332-E96, layer 1h, AA98, Burial 13; (b) Zea mays pollen (40×), CP C5, N397-E117, AA204; (c) Opuntia sp. (1×) CV C2, N332-334-E93, layer 1a-1b, AA77b; (d) Opuntia sp. pollen (100×) CV C3 N330-31-E75, AA99. (Color online)

Figure 4. (a) Salvia sp. (2×) CV C2, N332-E95, layer 1g, AA90; (b) Portulaca sp. (3.2×), CV C2, N333-34 E93, layer 1a-1b, AA77b; (c) Phaseolus sp. CP C1, N357-E116, layer 2a, AA157, 3-Dimensional Register 3700; (d) Jaltomata sp., (3.2×) CP C1, N358-E124, layer 1s/Earth floor 10. (Color online)

Table 2. Plant Taxa Recovered from Cueva de las Varillas and Cueva del Pirul (S = Seeds, P = Pollen).

In the Cueva de las Varillas during the Coyotlatelco phase, macrobotanical remains of maize, amaranth, purslane, chia, and beans were present in both silos and hearths but were absent in burials. Chenopods, however, were found in silos, hearths, and burials. During the subsequent Mazapa phase, maize, amaranth, chenopod, tuna, chía, and jaltomate were present in all three contexts, whereas beans were only recovered from silos and purslane was restricted to hearths and burials. During the Aztec occupation, only hearths provided relevant plant remains. Taxa in Aztec hearths included maize, amaranth, chenopods, chía, purslane, and jaltomate, although sunflower (Helianthus sp.) was recovered from a concentration of diverse materials corresponding to this occupation. Pollen evidence for maize and cheno-ams was recovered in silos, hearths, and burials during the Coyotlatelco and Mazapa phases, but only in hearths during the Aztec occupation (Supplementary Table 1).

In the Cueva del Pirul, macrobotanical remains of the aforementioned plant taxa were less plentiful, and their distributions differed somewhat from those in Cueva de Varillas. Only chenopods and maize were present in silos, hearths, and burials in Coyotlatelco contexts; amaranth was present in silos and burials, beans and purslane were present in silos, tuna and jaltomate were in hearths and burials, and chia was found in hearths. Sunflower was recovered from a concentration of ceramic debris as well. During the subsequent Mazapa occupation, amaranth, chenopod, and maize, together with jaltomate and purslane, were present in hearths and burials. Beans were present only in silos, and chía was associated with hearths during this phase. Maize, amaranth, and chenopods were recovered from hearths in this tunnel from the Aztec occupation.

There was considerably less pollen evidence in Cueva del Pirul than in Cueva de las Varillas. Cheno-ams were recovered in silos and burials corresponding to the Coyotlatelco occupation, but during the Mazapa phase were present in silos, hearths, and burials. Cheno-ams and maize pollen were present in hearths during the Aztec occupation as well.

In both Coyotlatelco and Mazapa phase contexts, three taxa were relatively common: Zea mays (maize), Amaranthus sp. (amaranth), and Chenopodium sp. (McClung de Tapia, Tapia-Recillas et al. Reference de Tapia, Emily, Ibarra-Morales, Cristina Adriano-Morán, Herrera-Escobar and Linda2023). Although found in both quarry tunnels, they were more numerous in Varillas, particularly during the Coyotlatelco occupation. For example, a storage installation in Chamber 3 of the Cueva de las Varillas, AA100, is one of several such structures in which large quantities of chenopods were recovered (Supplementary Figure 1; Supplementary Table 3). Maize was minimal in AA 99, west of AA 100, although chenopods were predominant in this context. In Cueva del Pirul, AA 161, a fragmented silo in Chamber 1, chenopods were similarly predominant together with cheno-am pollen; there was only a scarce presence of maize and amaranth (Supplementary Table 3). We interpret notable quantitative differences among plant taxa between the two tunnels as a product of preservation factors, human and faunal disturbance regimes, preparation and consumption habits, and variable seed production in different taxa; however, the abundance of chenopods led us to hypothesize their intensive use.

Considerable disparity among the frequencies of different plant taxa in both silos and other contexts represents a limiting factor to comparing them (Supplementary Table 3). As a result, we grouped taxa recovered from the silos according to their provenience: Cueva de las Varillas (CV) and Cueva del Pirul (CP). A two-sample Kolmogorov-Smirnov test (Shennan Reference Shennan1997) was carried out, and results from both tunnels were evaluated at significance levels of 0.05 and 0.001 (Table 3). The observed difference between the two samples is greater than the minimum required to reject a null hypothesis that the samples are drawn from the same distribution (Supplementary Figure 2).

Table 3. Cumulative Frequencies for Macrobotanical Taxa from Cueva de las Varillas (CV) and Cueva del Pirul (CP) Used in the Kolmogorov-Smirnov Two-Sample Test.

A morphological analysis of both complete and fragmented chenopod achenes indicates that the specimens generally correspond to nondomesticated plants (Chenopodium berlandieri), which perhaps were cultivated, although foraging is not excluded. High counts of charred and uncharred achenes in diverse contexts, particularly in silos, favor their possible cultivation. However, the margins of these achenes are generally biconvex or slightly rounded rather than truncated, a sign that they were not yet fully domesticated. Although both amaranth and chenopod greens provide a nutritive vegetal resource, the storage of achenes suggests that they were possibly ground and used as flour in atoles or other preparations, although the consumption of leaves and immature inflorescences is also probable.

Post-Teotihuacan Agricultural Production in the Teotihuacan Valley

Soil profiles studied in different sectors of the valley between 1992 and 2014 suggest a characteristic buried black soil horizon, broadly distributed in different geomorphological positions in the Teotihuacan region and either overlain by up to several meters of redeposited sediments or exposed on eroded surfaces of Cerro Gordo and the Patlachique Range (González Arqueros Reference González Arqueros2014; McClung et al. Reference McClung, Emily, Gama Castro, Solleiro Rebolledo and Sedov2005; Sánchez-Pérez et al. Reference Sánchez-Pérez, Solleiro-Rebolledo, Sedov, McClung de Tapia, Golyeva, Prado and Ibarra-Morales2013; Stahlschmidt et al. Reference Stahlschmidt, McClung de Tapia and del Carmen Gutiérrez-Castorena2019). Although the contribution of erosive events to the formation of the modern landscape has been apparent for decades, the widespread distribution of the black soil suggests prior availability of more fertile soil resources in the region than usually considered.

Plant remains from several archaeological excavations—particularly specimens from Cueva de las Varillas and Cueva del Pirul—suggest a mixed subsistence base that was partially dependent on gathering possibly noncultivated taxa such as amaranth and chenopods, together with maize and other cultigens. The favorable preservation of remains in these tunnels provides a unique opportunity to develop new hypotheses concerning procurement and productive subsistence practices and their organization in post-Teotihuacan communities. Future studies should incorporate the following analytical techniques: systematic phytolith and starch grain analyses of residues in ceramic vessels and dental calculus, the establishment of baseline reference collections of starch, and the application of advanced techniques of phytolith analysis and interpretation.

From a regional perspective, erosion and sedimentation suggest an unknown number of Epiclassic and Early Postclassic sites that are not visible on the surface of the alluvial plain, rendering previous population estimates unverifiable. Extension of the black soil in prehispanic times (Sánchez-Pérez et al. Reference Sánchez-Pérez, Solleiro-Rebolledo, Sedov, McClung de Tapia, Golyeva, Prado and Ibarra-Morales2013) and its hypothesized agricultural potential compel a reassessment of the productivity of the region’s subareas. Evidence for prehispanic inhabitants’ use of a range of locally available subsistence resources, the distribution of potential agricultural lands, and considerable landscape modifications suggests the need to review past interpretations. Favorable preservation of plant remains in the quarry tunnels east of the Sun Pyramid expands the panorama of post-Teotihuacan subsistence, contributing to the legacy of traditional Mesoamerican foodways and landscape management through procurement, as well as the production of plant resources.