FORMATIVE LITHIC ECONOMIES IN THE CENTRAL HIGHLANDS

Lithic economies were one of the mechanisms that integrated cultural traditions from eastern and western Mesoamerica in Mexico's central highlands during the Formative period (Plunket and Uruñuela Reference Plunket and Uruñuela2012). Residents exploited local sources of obsidian, chert, basalt, and felsic stones, if any, or acquired obsidian through regional and interregional exchange networks supplied by intermittent household production. The networks were accessed primarily through gateway communities, emerging urban centers, and cities (Boksenbaum et al. Reference Boksenbaum, Tolstoy, Harbottle, Kimberlin and Neivens1987; Charlton Reference Charlton and Hirth1984; Healan Reference Healan2019; Johnson and Hirth Reference Johnson and Hirth2019; Nichols and Stoner Reference Nichols and Stoner2019; Tolstoy et al. Reference Tolstoy, Fish, Boksenbaum, Vaughn and Earle Smith1977). Major obsidian sources include the Mesa Central sources northeast of Mexico City (Paredón, Tulancingo, Otumba, and Pachuca or Sierra de Las Navajas, hereafter SDLN); Sierra Madre Oriental sources in eastern Puebla and western Veracruz (Oyameles/Zaragoza, Guadalupe Victoria, and Orizaba); and the Ucareo-Zinapecuaro source area in Michoacán (Figure 1). Clark (Reference Clark, Johnson and Morrow1987) proposed that regional obsidian exchange networks developed due to elite control associated with the rise of chiefly centers, but more recent work suggests a stronger role for independent consumer demand (Hirth et al. Reference Hirth, Cyphers, Cobean, De León and Glascock2013). Otumba was the dominant source for obsidian tools at most Early and Middle Formative sites in the Basin of Mexico (Johnson and Hirth Reference Johnson and Hirth2019:304). However, lower frequencies of other obsidian sources at early sedentary sites in the Basin also indicate long-distance exchange networks following natural transportation corridors leading to the Gulf Coast, Mixteca Alta, and the Valley of Oaxaca (Blomster and Glascock Reference Blomster and Glascock2011; Carballo and Pluckhahn Reference Carballo and Pluckhahn2007; Cobean Reference Cobean2002; Parry Reference Parry1987). For example, five obsidian sources appear at the village of Coapexco (1520–1350 cal b.c.), and four of these sources comprise at least 10 percent of the lithic assemblage (Johnson and Hirth Reference Johnson and Hirth2019:304). Coapexco's location in the Amecameca pass made it a likely effective gateway community that imported pre-prepared cores of Ucareo-Zinapecuaro obsidian from the west and Zaragoza obsidian from the east and exported pressure blades to consumer sites in the central highlands (Johnson and Hirth Reference Johnson and Hirth2019:307).

In their discussion of Formative obsidian networks, Johnson and Hirth (Reference Johnson and Hirth2019:300) identify “processor” sites as communities with inhabitants who engaged in mining and preparing obsidian for exchange, which could have involved the creation of value-added items in the form of finished tools. Processor sites with evidence for mining/quarrying or core preparation have been found for the Classic onward (e.g., Cobean Reference Cobean2002; Hernández and Healan Reference Hernández and Healan2008; Pastrana Reference Pastrana1998; Pastrana and Domínguez Reference Pastrana and Domínguez2009), but they have remained comparatively elusive for the Formative. For example, despite its very high density of obsidian artifacts and short distance from the Otumba obsidian source, the small village of Altica (1250–800 cal b.c.) did not systematically prepare obsidian nodules, cores, or tools for exchange (Healan Reference Healan2019). Instead, residents of this earliest settlement in the Teotihuacan Valley obtained Otumba obsidian nodules to produce expedient percussion flakes and blades, unlike the bipolar tools commonly found at contemporaneous sites in the Basin (Boksenbaum Reference Boksenbaum1980) and other regions in Early to Middle Formative Mesoamerica (e.g., Clark Reference Clark, Johnson and Morrow1987; Parry Reference Parry1987; Walton Reference Walton2017). The use-wear data from Altica indicate that residents used their percussion tools for subsistence (foraging and non-intensive maize agriculture) and woodworking attributed to the construction and maintenance of houses and agricultural plots (Walton Reference Walton2020).

Over the Middle Formative (900–500 b.c.), the population increased and some groups moved to previously unoccupied areas. Social differentiation began to increase at functionally urban centers such as Chalcatzingo, but expressions of social difference became more pronounced at the larger Late Formative (500–100 b.c.) cities of Cuicuilco and Xochitecatl, which exhibited political and religious institutions through monumental architecture analogous to later Classic (a.d. 100–600) cities. Social differentiation generally increased but manifested differently at smaller towns and villages in the Late and Terminal (100 b.c.–a.d. 100) Formative (Carballo Reference Carballo2009, Reference Carballo2011b; Plunket and Uruñuela Reference Plunket and Uruñuela2012; Serra Puche and Lazcano Arce Reference Serra Puche and Lazcano Arce2011). The trade of obsidian prismatic blades (i.e., blades removed from prepared blade cores by pressure, hence the nomenclature of pressure blades) began during the Archaic (ca. 4000 b.c.; Macneish et al. Reference Macneish, Nelken-Terner and Johnson1967:22; Niederberger Reference Niederberger1976), but they were not traded extensively across the central highlands until the Late Formative. Clark (Reference Clark, Johnson and Morrow1987) originally attributed this increase in pressure blade production and trade to the emergence of social elites. In the Late Formative, a concentration of lithic production debris attached to the city of Xochitecatl's Edificio del Serpiente indicates institutional sponsorship of lithic production events utilizing labor tribute, an arrangement which may foreshadow later state-sponsored production events near Teotihuacan's Moon Pyramid (Blanco Reference Blanco and Paz1998; Carballo Reference Carballo2011a). However, recent studies have cast doubt on the purported evidence for elite sponsorship from Chalcatzingo and Loma Torremote. These studies developed new models highlighting source proximity, access to exchange networks, and population increase as primary factors linked to higher frequencies of pressure blades in lithic assemblages over the course of the Formative (Walton Reference Walton2017; Walton and Carballo Reference Walton and Carballo2016). Evidence from the urban center of Chalcatzingo, which has the earliest well-documented blade workshop deposit (T-37), lends itself to conflicting interpretations about how production debris is linked to one (Grove Reference Grove1987:75–76) or multiple (Hirth Reference Hirth2008) residences. Santley's (Reference Santley, Santley and Hirth1993) interpretation of lithic production at the town of Loma Torremote is problematic in a different way. Here, Santley (Reference Santley, Santley and Hirth1993:82) identifies an elite residence as the head of a local redistributive economy that provided obsidian pressure blades to other residences but argues that this and other diachronic developments at the site were all “density-dependent phenomena.” While a concentrated zone of blade production correlates with a probable elite/political leader's house compound cluster at Loma Torremote, correlation does not equal causation. Instead, I argue that dense residential nucleation, an overall increasing population, and Loma Torremote's position in the regional economy—rather than the correlating increase in social status differentiation—together created a setting where inhabitants of one house compound could supply other neighboring house compounds by increasing their scale of lithic production, especially if raw materials were easy to acquire. De León and colleagues (Reference De León, Hirth and Carballo2009) demonstrate that obsidian was indeed easy for residents in the Basin of Mexico to obtain—primarily in the form of whole blades—and select sites along the lakeshores specialized in obsidian production and trade via water transport (e.g., Boksenbaum et al. Reference Boksenbaum, Tolstoy, Harbottle, Kimberlin and Neivens1987).

This model for an increasing scale of blade production in connection with more spatial restriction of the activity at Loma Torremote is supported by a contrasting model in northern Puebla-Tlaxcala Valley, where a different set of conditions lead to different testable expectations for the organization of domestic lithic production. The smaller and lower populated sites of Amomoloc, Tetel, Las Mesitas, and La Laguna were located farther from obsidian sources and regional exchange systems and settlement patterns were relatively dispersed, which created scenarios where all households provisioned themselves and independently conducted lithic production (Walton and Carballo Reference Walton and Carballo2016). Resource accumulation strategies shifted away from local cherts and Sierra Madre Oriental obsidian sources toward the use of Mesa Central obsidian sources and fewer raw material sources around 600 b.c. (Carballo et al. Reference Carballo, Carballo and Neff2007). Paredón became the primary source for blades and other tool forms increasingly over time, while the importation of whole SDLN blades also increased from La Laguna's Late Formative to Terminal Formative occupation. Local blade production was not conducted at Amomoloc, where residents imported whole blades. Starting in the Late Formative, blade production took place primarily in all residential contexts, rather than institutional contexts, and a production strategy for exchange did not emerge in either elite or commoner residences as social differentiation increased and more rural areas became integrated with regional economic systems. The primary lithic production zone (Area I) located just beyond the main civic-ceremonial zone at Terminal Formative La Laguna, however, indicated that more frequent lithic production activities took place in a combined domestic-communal setting linked to suprahousehold feasting and communal ritual (Carballo et al. Reference Carballo, Barba, Ortíz, Blancas, Cingolani, Toledo Barrera, Walton, López and Couoh2014a; Walton and Carballo Reference Walton and Carballo2016). The most active blade makers were not necessarily the most productive nor skilled. Blade production output levels doubled from the Late to Terminal Formative occupations at the secondary production zones linked to elite (Area H) and commoner (Area F) residences, but the primary blade production zone at Area I increased its productivity by only 23 percent (Walton Reference Walton2017:Table 8.2). The Area I production zone exhibits both higher rates of overshot and other blade production errors compared to the secondary production zones. The blade makers in these commoner and elite residences were equally skilled. Lower densities of blade production- and blade consumption-related artifacts at Area H compared to Area F, despite similar blade production outputs, further indicate that these equally skilled commoners were more active contributors to the site's blade economy.

The production, trade, and consumption of long-distance prestige goods, usually classified as network strategies (Blanton et al. Reference Blanton, Feinman, Kowalewski and Peregrine1996), were a prominent focus of Middle Formative economies in many regions of Mesoamerica. Blanton and colleagues (Reference Blanton, Fargher, Heredia Espinoza and Blanton2005) link the increase in obsidian production in the central highlands during the Early to Middle Formative (ca. 1200–500 b.c.) to a regional economic transformation focused on prestige or socially valued goods. They argue that this transformation produced few, if any, systemic changes to agroeconomy, demography, market systems, or household economic strategies. Compositional and technological analyses have produced little to no evidence indicating that obsidian artifacts were viewed as prestige goods by Early and Middle Formative residents of the central highlands. However, obsidian tools may have been used to craft prestige goods from other materials, which can be detected through use-wear analyses. Obsidian began to be transformed into specialized tools designed for domestic rituals during the later Middle Formative but more frequently for public ritual practices in the Terminal Formative (Walton Reference Walton2021; Walton and Carballo Reference Walton and Carballo2016). Simply put, social elites and public institutions neither systemically controlled or sponsored lithic production systems nor stimulated consumer demand for obsidian prestige goods during the Early and Middle Formative. However, a noticeable shift took place around 500 b.c. with an increase in obsidian pressure blade production and the growth of distribution systems, reflecting an economic transformation in regional goods—defined by links to regional-scale systems of tribute flow and periodic markets—in response to population growth, regional urbanism, and state formation (Blanton et al. Reference Blanton, Fargher, Heredia Espinoza and Blanton2005; Carballo Reference Carballo2016). Here, the effects of elites and social institutions on Formative lithic economies can be detected through compositional and technological analyses, and the addition of use-wear analyses may enable us to see the impacts of these changes on individual households.

SITES AND EXCAVATION CONTEXTS

The villages of Amomoloc (900–650 b.c.), Tetel (750–500 b.c.), and Las Mesitas (600–500 b.c.), and the town of La Laguna (600–400 b.c. and 100 b.c.–a.d. 150) are in northern Tlaxcala, adjacent to the Tlaxcala Corridor that connects the Basin of Mexico with the Gulf Coast to the east and the Maya region to the south (Figure 1). The first permanent residents of northern Tlaxcala migrated as fully operational maize agriculturalists from Early Formative centers, likely in the adjacent Puebla-Tlaxcala Valley to the south (Lesure et al. Reference Lesure, Borejsza, Carballo, Frederick, Popper and Wake2006:489). These migrations to higher elevations (over ca. 2,400 m asl) in Tlaxcala reflect macroregional processes of population in-filling across the peripheral landscapes of the central highlands by 800 b.c. (Lesure Reference Lesure2014:6). Pottery and figurines from Amomoloc, Tetel, and Mesitas show close cultural ties with the nearby contemporaneous site of Xochitecatl, but there is no current evidence to support a model of Xochitecatl's direct political control over north-central Tlaxcala during the Middle and Late Formative (Lesure Reference Lesure2014:6).

Lesure (Reference Lesure2014:8) defines Amomoloc as a modest village, between two and seven hectares, that was largely a single component site. The excavation contexts include loose domestic refuse and secure features comprising refuse-filled pits, roasting pits, and one burial. Carballo and Lesure (Reference Carballo, Lesure and Lesure2014:23–25, Figure 2.7) hypothesize the boundaries of seven distinct house yards at Amomoloc, based on concentrations of secure pit features.

Lesure (Reference Lesure2014:8) defines Tetel as a small village that covered about two hectares. Lesure and Carballo (Reference Lesure, Carballo and Lesure2014:54–69, Figure 3.3) identify five possible house yards based on loose domestic refuse and secure pit features filled with domestic refuse and two deposits of human bones. A basaltic extrusion lies just 300 m from the site, and it supplied residents with raw material for flaked basalt tools, which were not included during technological analysis (Carballo Reference Carballo2004).

Lesure (Reference Lesure2014:8–9) defines Las Mesitas as a dispersed homestead, which was likely part of a scatter of dispersed homesteads, each surrounded by cultivated fields. The excavations themselves originated from an eroded road cut, but a light scatter of sherds around the site covers about seven hectares. Excavated materials came mostly from areas A and F, which likely represent one house yard, but additional house yards may have been located near areas D and E (Carballo and Carballo Reference Carballo, Carballo and Lesure2014:76, Figure 4.2). The excavation contexts include loose domestic refuse and secure refuse-filled pits, one of which also contained a human burial.

Carballo (Reference Carballo2016) classifies La Laguna as a town (>30 ha) with two Formative occupations prior to its abandonment near the onset of the Classic and Teotihuacan's militaristic expansion across the central highlands. Domestic contexts used for use-wear analyses comprise both occupations across three distinct household compounds—Area I, Area H, and Area F—ranging from the site center to the periphery (Walton and Carballo Reference Walton and Carballo2016:Figure 2). Excavations in Area I revealed a house compound and outdoor space, and during the Terminal Formative it functioned as a combined residential and communal space for suprahousehold rituals and food storage, production, and consumption (Carballo et al. Reference Carballo, Barba, Ortíz, Blancas, Cingolani, Toledo Barrera, Walton, López and Couoh2014a). Excavations in Area H uncovered an elite residential platform with an additional kitchen and storage facility, while excavations in Area F discovered a single-structure commoner residence (Carballo Reference Carballo2009).

TOOLKITS AND SAMPLING STRATEGY

The artifacts that comprise the sample for use-wear analysis (Table 1) were chosen as part of a larger project investigating how different obsidian sources and lithic technologies may have been used for specific tasks in domestic spaces within sites and over time in the central highlands (Walton Reference Walton2017). To best identify and evaluate these patterns, I chose use-wear specimens—after completing technological classifications for each assemblage—first by scarcity of technological forms and second by proportion to their occurrence. The specimens almost exclusively originate from secure excavation contexts in association with structures (e.g., pit features, occupation floors, structural collapse, and sealed platform fill), keeping the number of specimens from unsecure excavation contexts (e.g., surface lots, geological disturbance, bioturbation, and looter pits) limited to associations with ceramic phases and general site areas to a bare minimum necessary for achieving the project's goals. When reading Table 1, it is important to note that the tool counts originate from all excavation contexts at Amomoloc, Tetel, Las Mesitas, and Terminal Formative La Laguna, respectively. The Late Formative excavation lots at La Laguna were identified only by clear stratigraphic and archaeological evidence that differentiated them from the higher Terminal Formative excavation lots. Therefore, all tool counts presented for Late Formative La Laguna reflect only secure excavation contexts. The tool counts presented for the extensively excavated Terminal Formative occupation at La Laguna include those from both secure and unsecure excavation contexts linked to households and public spaces because eight use-wear specimens were chosen from unsecure household excavation contexts and technological diversity in public lithic consumption is essential to consider for diachronic analysis. We identify 723 tools from the most secure Terminal Formative contexts (Walton and Carballo Reference Walton and Carballo2016:Table 1), compared to the 1,086 tools listed for the Late Formative occupation, making the 125 Terminal Formative use-wear specimens (17.3 percent) proportionately comparable to the other samples in this study (Table 1).

Table 1. Sampling strategy for high-magnification use-wear analysis. Use-wear specimen count and percentages are in parentheses. LF, Late Formative; TF, Terminal Formative.

^a Refer to the end of the first paragraph of the section Toolkits and Sampling Strategy, which explains how the 125 specimens from Terminal Formative La Laguna more accurately represent 17.3 percent of all tools from the most secure contexts, whereas this table presents the sampling strategy in terms of all excavation contexts at all sites.

My technological classification system is based on experimental replication studies (Carballo Reference Carballo2011a; Clark and Bryant Reference Clark and Bryant1997; Hirth and Flenniken Reference Hirth, Flenniken and Hirth2006) in addition to my own observations during analysis. Bipolar flaking refers to the smashing of either small irregular pebbles/cobbles (Boksenbaum Reference Boksenbaum1980:20–23) or spent blade cores on anvils to recover flat flakes (Figure 2f) and angular chunks. A bipolared blade can be produced by taking a blade and striking one end with a hammer stone while the opposite end is placed on an anvil. Unifacial forms include “scrapers,” outlined originally by Tolstoy (Reference Tolstoy, Ekholm and Bernal1971), created from percussion flake or blade banks using percussion trimming along one or more edges along one face or side of the material (Figure 2r), and what I call unifacial tools, which include variously shaped pieces with percussion and/or pressure trimming along one side or face of the material that do not fit within established scraper forms. Bifacial tool categories include completed and fragmented knives (Figure 2o), spear or atlatl dart points (Figures 2c–2e, 2k, 2l, and 2q), and drills produced either through percussion trimming or, more commonly, bifacial pressure retouch on late-series pressure blade segments (Figure 2a). Artifacts with bifacial trimming that do not fit within these categories are grouped under the label bifacial trimmed tool.

Figure 2. Photographs of use-wear specimens from Amomoloc: (a and b) Bifacial drills; (c–e) bifacial points; (f) bipolar flake; Tetel: (g) percussion blade; (h) late-series pressure snapped blade segment; (i) late-series pressure proximal blade segment; (j) bloodletter; (k) bifacial point; Las Mesitas: (l) bifacial point; La Laguna: (m and n) bifacial drills; (o) bifacial knife; (p) bloodletter; (q) bifacial point; (r) unifacial scraper. Photographs by the author.

Blades are defined as sequential percussion (Figure 2g) and pressure (Figure 2i) removals from blade cores. Early-series pressure blades exhibit dorsal scars from prior percussion blade removals, whereas late-series pressure blades exhibit only dorsal scars from prior pressure removals. Some late-series pressure blade segments—referred to as snapped blades—were produced by intentionally snapping off the proximal and distal ends, leaving the medial section flat (Figure 2h). Blades identified as notched or trimmed were deliberately modified as such prior to their use.

Technological criteria that can be used to identify bloodletters include very thin (i.e., 0.5 cm or often less in width) and precise bifacial pressure-trimming flake scars, or retouch, on distal and/or proximal ends of a pressure blade that is less than 1 cm wide (Figures 2j and 2p), or a similarly thin blade with an unusually tapered distal termination that ends with a fine point (Walton Reference Walton2021; Walton and Carballo Reference Walton and Carballo2016:115). Stemp and colleagues (Reference Stemp, Peuramaki-Brown and Awe2019) find that measuring cutting-edge/mass ratios to identify the finest range of blades in an assemblage can help to predict which blades may have been designed and used as bloodletters. Eccentrics are exquisitely knapped bifaces shaped into symbolic geometric, anthropomorphic, serrated, and zoomorphic forms, among others, and may be large in size (Walton and Carballo Reference Walton and Carballo2016:Figures 9–11). Eccentrics were recovered only in association with public ritual spaces at Terminal Formative La Laguna; thus, they were not sampled for this study focused on households.

METHOD FOR HIGH-MAGNIFICATION USE-WEAR ANALYSIS

The term “use-wear” applies to surface modifications that occurred during all stages of an artifact's use-life history (e.g., Fullagar Reference Fullagar, Balme and Paterson2006), which can include overlapping activities, hafting, burning, and post-discard soil abrasion. High-magnification use-wear analysis (e.g., Keeley Reference Keeley1980; Semenov Reference Semenov1964; Vaughan Reference Vaughan1985) can detect four attributes created by acts of obsidian tool use: striations, edge rounding, micropolishes, and residues (Kononenko Reference Kononenko2011:7–9; Walton Reference Walton2019:898). Striations, micropolishes, and residues are much more reliable attributes for determining specific materials, while edge rounding is more suitable for identifying materials according to a range of densities or activity durations.

Striations can be described in terms of their morphology (e.g., sleek versus rough-bottomed) and orientation (e.g., parallel versus perpendicular to the working edge). Different materials and activities can affect the locations of striations on tool surfaces. Thus, it is important to note whether striations are isolated or located near other striations; different materials tend to affect this characteristic more than activity motion or duration.

Edge rounding refers to the erosion/smoothing of tool edges, and degrees of edge rounding increase with denser materials and/or longer activity durations. I classify degrees of edge rounding as very light, light, medium, intensive, and very intensive, following a similar qualitative classification scheme used by Kononenko (Reference Kononenko2011). It is necessary to differentiate edge damage—the fracturing or chipping of a tool edge from either use or post-depositional processes—from edge rounding, which can be produced only through durations of tool use.

Use-wear polish can be created by repeated physical contact between tool surfaces and different materials. Researchers debate the specific mechanisms that contribute to polish formation. Fullagar (Reference Fullagar1991:2–3) summarizes theories of polish formation on stone tools and demonstrates that amorphous silica is a major contributor toward polish formation on stone tools used to process plants. Christensen et al. (Reference Christensen, Calligaro, Consigny, Dran, Salomon and Walter1998) argue that polish itself is an encrusted coating of the worked material spread across the irregular surface of the tool. There are four stages of polish development for obsidian tools (Fullagar Reference Fullagar1991:6; Kononenko Reference Kononenko2011:8). In stage 1, freshly flaked edges experience very light edge rounding as jagged edges and loosely adhering flakes are worn back. In stage 2, patches of smooth polish develop as the surface is abraded, peaks are leveled, subsurface cracks are deepened, and granular material is deposited into surface depressions. In stage 3, polish characteristics are strong enough to be linked with specific worked materials. During this stage, subsurface cracks are extended and flaked out of the surface just as other surface defects are smoothed out via abrasion. In stage 4, an extensive polished surface can be developed but only through contact with moist siliceous plant material. The distinguishable clarity and thickness of polish or pattern of alteration on a tool edge can be affected by numerous factors including activity duration, number of strokes, applied force, and the material properties of the tool itself.

Following Kononenko (Reference Kononenko2011:4), residues are the materials that are either attached to or absorbed by a tool surface. Residues often appear trapped within the varying topographies of microcavities on tool surfaces, but the exact formation processes that cause these residues to remain in contact with tool surfaces are still under investigation (e.g., Fullagar Reference Fullagar, Balme and Paterson2006). In this study, I recognize the colors and basic morphologies of residues that remained on tool surfaces after the artifacts were cleaned. Here, I recognize blood residues based on visual characteristics shared by blood residues (Walton Reference Walton2019:Figure 13) identified through chemical testing with Hemastix® active reagent strips, following a protocol developed by Matheson and Veall (Reference Matheson and Veall2014).

The use-wear characteristics and obsidian tool functions identified here are based on my systematic program of 300 experiments with 145 obsidian tool specimens that controlled for two obsidian sources, two activity durations (5 and 15 minutes), and 29 different materials that were accessible to prehispanic residents of central Mexico (Walton Reference Walton2019). In March 2018, I also performed four experiments using obsidian percussion flakes to cut slate and observe the resulting use-wear characteristics. The results from those experiments are the basis for identifications of stone cutting on artifacts in this study. Obsidian tools for experimentation were created to replicate six common tool forms found in central Mexican archaeology: percussion flakes, percussion blades, unifacial scrapers, bifacial knives, drills, and retouched pressure blades labeled variously as needles, perforators, or bloodletters (Walton Reference Walton2017:70–84). Each freshly knapped tool specimen for the study was cleaned and photographed before use to provide control data for each experiment (Figure 3). All specimens were used by hand with a single tool motion for each one.

Figure 3. Photographs of ventral surface topographies on four unused obsidian tools. Photographs by the author.

Comparing the experimental use-wear patterns replicated by different studies (Aoyama Reference Aoyama1995; Kononenko Reference Kononenko2011; Stemp Reference Stemp2016a; Walton Reference Walton2019), along with their own unique findings linked to specific resources within their respective geographic regions, reveals that some specific types of plants can be distinguished from broader categories of plants. The most generalized category of plant materials used with the method of high-magnification obsidian use-wear analysis is “soft plants,” which includes a wide array of plants (e.g., gourds, cactus leaves, cactus fruits, potatoes, tomatoes, avocados, and goosefoot) that produce very light to light edge rounding and striations that are extremely fine, thin, and isolated near a tool's puncture point (Figure 4a). Thicker grasses can produce more frequent and thicker striations, but generally their use-wear patterns—identified by Kononenko (Reference Kononenko2011:76) as part of a “non-woody plant” group—are essentially identical to those documented in the soft plant category that Aoyama (Reference Aoyama1995) and I (Walton Reference Walton2019) prefer to use. While the working of soft woods (Figure 5d) and hard woods can be distinguished in experimental studies based on comparing striation densities (Walton Reference Walton2019: Figures 5 and 6), making these distinctions becomes more challenging with archaeological specimens, often due to the presence of overlapping or adjacent activities that involved soft wood and hard wood. Thus, the safest approach is to use a generalized wood category, which I do here. Maize can be distinguished apart from grasses and other soft plants because it produces longer striations, polish development located farther beyond a tool edge, and higher degrees of edge rounding (Figure 4b). Maguey heart scraping can be identified because of the signs of that very specific tool motion: restricted groups of short perpendicular striations bunched together near the impact point, which further displays very light to light edge rounding (Walton Reference Walton2019: Figure 8). Maguey leaf can be identified through its extensive polish development, which can be present even at five minutes of tool use (Figure 4d).

Figure 4. Photographs of experimental results using obsidian tools. (a) 15 minutes of goosefoot cutting; (b) 15 minutes of maize cutting; (c) 15 minutes of turkey cutting; (d) 15 minutes of maguey leaf scraping; (e) 5 minutes of rabbit skin scraping with white arrow indicating striations; (f) 25 strokes of pig skin piercing. Photographs by the author.

Figure 5. Photographs of experimental results using obsidian tools. (a) 15 minutes of clay scraping; (b) 15 minutes of red ware ceramic cutting; (c) 5 minutes of boiled chicken bone cutting; (d) 15 minutes of huisache (wood) whittling; (e) 20 minutes of shell boring; (f) 5 minutes of slate cutting. Photographs by the author.

While the formation of a bright polish or film created by meat cutting usually takes about 40–55 minutes to form (Hurcombe Reference Hurcombe1992:43–44; Stemp Reference Stemp2016a:168), blood residues (Walton Reference Walton2019:Figure 9) and thick striations isolated near the tool edge (Figure 4c) can remain on an obsidian tool edge after only 5 minutes of tool use. The scraping of skin/fresh hide produces greasy, rounded edges and often visible striations on ventral surfaces positioned very close to the tool edge after 5 minutes of tool use (Figure 4e). The piercing of pig skin—used as a close substitute for human skin—can produce Stage 1 polish with very short diagonal striations and blood residues after only 5 strokes, while 25 strokes ensures that striations will be visible (Figure 4f).

Clay smoothing/shaping can be detected through striations with various lengths and widths that cross each other and run perpendicular and diagonal to a tool's edge, which create a very unpredictable or random scratchy pattern (Figure 5a). This randomness is likely due to the dispersion of various mineral inclusions within clay structures. The cutting of ceramic sherds can be detected via Stage 3 polish with intensive edge rounding and multicolored residues trapped in microcavities (Figure 5b). White powdery residues and very intensive edge damage resulting in crushed, multifaceted edge topographies help to distinguish shell working (Figure 5e) from bone working (Figure 5c), which produces a smoother, pitted polish that extends across the utilized edge towards the dorsal and ventral centers of a tool. Stone cutting (Figure 5f) produces Stage 3 polish with very intensive edge rounding and sharply defined striations via attrition.

The documentation and photography of use-wear characteristics on lithic artifacts was performed with a Brunel SP 202-XM dual metallurgical microscope and Canon Rebel XT EOS 350D. Each specimen was immersed in a warm 10 percent HCL solution for 10 minutes. After HCL immersion, each specimen was removed while wearing latex-free gloves and wiped clean with Kimwipes. Each specimen was viewed through incident light (bright field) and LED lights (dark field) because incident light is more useful for identifying polish stages and striations, while the LED lights are more useful for identifying residues. Both 100× and 200× magnifications are effective options for classifying and photographing use-wear patterns, while magnifications of 400× and 600× can be useful for distinguishing between very similar-looking polish stages/types and identifying residues.

RESUMEN

Los análisis a gran aumento de huellas de uso crean datos que permiten estudios microeconómicos del consumo lítico, así como las actividades domésticas que complementan los estudios macroeconómicos de la producción y el intercambio del material lítico para mejorar colectivamente nuestras reconstrucciones de economías antiguas. En las últimas décadas, los análisis composicionales y tecnológicos han revelado cómo ciertas fuentes de obsidiana y tecnologías líticas fueron explotadas, producidas e intercambiadas en el altiplano central de México durante el período formativo (1500 a.C.–100 d.C.). Este artículo presenta un estudio sobre el uso de 275 artefactos líticos de cuatro sitios en el norte de Tlaxcala–Amomoloc (900–650 a.C.), Tetel (750–500 a.C.), Las Mesitas (600–500 a.C.) y La Laguna (600–400 a.C. y 100 a.C.–150 d.C.)—con el fin de comparar las actividades domésticas con las tecnologías líticas y evaluar sus roles en las economías regionales.

El análisis a gran aumento de huellas de uso puede detectar cuatro rasgos creados por el uso de herramientas de obsidiana: estriaciones, redondeo en los filos, micropulidos y residuos. Las características de uso y las funciones de las herramientas de obsidiana identificadas aquí se basan en mi programa sistemático de 300 experimentos con 145 especímenes de obsidiana que controlaron dos fuentes de obsidiana, dos duraciones de actividad (5 y 15 minutos), y 29 materiales diferentes a los que podían acceder las comunidades prehispánicas del centro de México. Los artefactos en este estudio fueron seleccionados como una muestra representativa dentro de la amplia gama de formas de herramientas completas presentes en los conjuntos líticos de los cuatro sitios.

Los resultados indican que los antiguos habitantes del norte de Tlaxcala usaban navajas de obsidiana para la subsistencia y la artesanía doméstica; la extracción de fibra de maguey para la producción textil aumentó con el tiempo, especialmente en hogares no pertenecientes a la élite. La preparación y el consumo de la carne adquirida mediante la caza, y otros métodos, aumentaron con el tiempo y las tecnologías bipolares se utilizaron como utensilios de cocina. El derramamiento ritual de sangre requería una tecnología específica, pero esta forma y otros artefactos no se intercambiaban como objetos de prestigio ni se usaban para fabricar objetos de prestigio, a menudo considerados como potencias principales de las economías en Mesoamérica durante el formativo.