Ancestral Puebloans

The Ancestral Puebloans—known in the Hopi language as the Hisatsinom ("People of Long Ago") and in older archaeological literature by the Navajo exonym Anasazi—were a Pre-Columbian Indigenous agricultural culture that inhabited the Colorado Plateau across the Four Corners region of the present-day United States (northwestern New Mexico, southwestern Colorado, southeastern Utah, and northeastern Arizona), bordered to the south and west by the contemporary Mogollon, Hohokam, and Patayan traditions. Evolving continuously from Late Archaic hunter-foragers who adopted Mesoamerican maize (Zea mays) and squash cultivation around 2100–1000 BCE, Ancestral Puebloan history is organized via the Pecos Classification (established by Alfred V. Kidder at the 1927 Pecos Conference) into the Basketmaker II–III and Pueblo I–IV periods, culminating in the monumental regional system of Chaco Canyon (~850–1150 CE) and the defensible sandstone alcove cliff dwellings of Mesa Verde, Canyon de Chelly, and Bandelier (~1150–1300 CE). Following the pronounced Great Drought of 1276–1299 CE (precisely dated to the calendar year by dendrochronology), Ancestral Puebloan communities migrated from the northern Four Corners mesas into the Rio Grande Valley, the Zuni Mountains, and the Hopi Mesas, where their direct biological and cultural descendants—the 21 federally recognized Pueblo tribes of New Mexico, Arizona, and Texas—thrive today.

Across the semi-arid Colorado Plateau (elevation 1,500 to 2,300 m, receiving only 150 to 350 mm of strongly variable bimodal winter-snow and late-summer monsoon rainfall and bounded by a short 110-to-130-day frost-free growing season), Ancestral Puebloan survival depended on ingenious micro-topographic water harvesting and soil conservation:

• Ak-Chin (Alluvial Fan), Check-Dam, and Waffle-Garden Hydrology: Farmers planted deep-rooted desert landraces of maize (Zea mays)—whose elongated mesocotyls can emerge from seeds planted 15 to 30 cm deep in moist subsurface sand!—at the mouths of ephemeral arroyos (ak-chin floodwater fields), behind thousands of stone check-dams (trincheras) stepped down canyon drainages to trap moisture and nutrient-rich silt, inside cobble-bordered gravel-mulch plots (which curtailed evaporative soil moisture loss and warmed spring soil temperatures), and inside gridded clay-rimmed waffle gardens.
• The "Three Sisters" Nutritional Synergy: Beginning in Basketmaker III (~500 CE), the pairing of maize, common beans (Phaseolus vulgaris), and squash (Cucurbita pepo / moschata) created a complete agro-ecological and biochemical symbiosis: Rhizobium bacteria in bean root nodules fixed atmospheric nitrogen (N₂ → NH₃) in nitrogen-poor desert soils; broad squash leaves shaded the soil to suppress weeds and evaporation; and in the human diet, the lysine and tryptophan amino acids abundant in beans complemented the methionine in maize (further unlocked as bioavailable niacin [vitamin B₃] when maize was boiled in alkaline wood-ash or lime water, nixtamalization, preventing pellagra), supplemented by domesticated turkeys (Meleagris gallopavo) raised primarily for feather blankets and ritual offerings until Pueblo III when turkey meat became a major dietary protein source (confirmed by turkey bone collagen δ¹³C ≈ -8‰ showing they were hand-fed stored maize!).

Between 850 and 1140 CE, Chaco Canyon—a 15-km-long sandstone canyon cut by the ephemeral Chaco Wash in the center of the arid San Juan Basin of northwestern New Mexico—became the political, architectural, and ceremonial capital of a regional network spanning 100,000 km² and over 150 outlier communities:

1. Monumental Core-and-Veneer Great Houses: Twelve monumental Great Houses—led by Pueblo Bonito, Chetro Ketl, Pueblo del Arroyo, Pueblo Alto, Peñasco Blanco, and the isolated Great Kiva of Casa Rinconada—were constructed along the canyon floor and northern cliff rim. Rising 4 to 5 stories high in a giant D-shaped amphitheater enclosing a divided central plaza with more than 650 rooms and 35 kivas, Pueblo Bonito was built using specialized Chacoan core-and-veneer masonry (Types I–IV): load-bearing stone walls up to 1 meter thick faced with thousands of tabular sandstone blocks hand-chipped into uniform courses and originally coated in bright white plaster.
2. specific Dendrochronological Construction Sequences and Distant Timber Hauling: Because A. E. Douglass and Thomas Windes dated thousands of preserved roof beams (vigas) inside Pueblo Bonito and Chetro Ketl via dendrochronology, archaeologists know the specific calendar years when individual wings were built (e.g., Old Bonito in 850–935 CE, followed by large-scale expansion waves in 1040–1085 CE). notably, over 200,000 straight ponderosa pine (Pinus ponderosa), Douglas fir, and Engelmann spruce trees (~5 m long, weighing 250–300 kg each) were felled with stone axes and carried largely by human hands without pack animals or wheels across 75 to 100 kilometers from subalpine forests atop the Chuska Mountains (to the west) and Mount Taylor / San Mateo Mountains (to the south)—proven by strontium isotope (⁸⁷Sr/⁸⁶Sr) matching of the archaeological wood to Chuska and San Mateo mountain soils (English et al., 2001).
3. Engineered Chacoan Roads and Cardinal/Solar Alignments: Radiating out from Chaco Canyon across the San Juan Basin is a network of over 650 kilometers of monumental engineered roads—including the Great North Road (running 50 km dead-straight at 0^° true North to the badlands of Kutz Canyon)—excavated 9 meters (30 feet) wide down to bedrock, bordered by earthen berms or stone curbs, and ascending vertical sandstone cliffs via rock-cut stairways rather than detouring around obstacles. Simultaneously, Anna Sofaer and colleagues documented archaeoastronomical alignments: both the Fajada Butte "Sun Dagger" (where three leaning sandstone slabs channel daggers of sunlight across two pecked spiral petroglyphs at the summer/winter solstices and the 18.6-year lunar standstill cycle) and the cardinal/solstice orientations of Pueblo Bonito and Casa Rinconada.
4. Long-Distance Mesoamerican Trade (Cacao, Scarlet Macaws, and Copper Bells): In 2009, Patricia Crown and W. Jeffrey Hurst analyzed organic residues inside distinctive tall, white-slipped Chacoan Cylinder Jars excavated from Room 28 of Pueblo Bonito and detected theobromine, proving that Chacoan elites imported Theobroma cacao (chocolate) from tropical Mesoamerica >1,800 km to the south, alongside live Scarlet Macaws (Ara macao) (bred in a specialized aviary at Paquimé/Casas Grandes and kept in Pueblo Bonito), 40+ cast copper bells from West Mexico, and over 50,000 turquoise beads and inlays buried in the sub-floor crypt of Room 33! In 2017, nuclear and mitochondrial ancient DNA sequenced by Douglas Kennett, Stephen Plog, and colleagues from nine elite individuals buried across 330 years (800–1130 CE) inside Room 33 of Pueblo Bonito revealed that all nine individuals shared the specific same mitochondrial haplotype (B2y1), proving that Chaco Canyon was governed for over three centuries by a hereditary matrilineal dynasty—directly paralleling the matrilineal clan leadership of modern Hopi, Zuni, and Acoma Pueblos.

Throughout the Pueblo I–III periods, the spiritual and social heart of every community was the kiva (a Hopi word meaning "ceremonial room"): a circular (or keyhole-shaped at Mesa Verde), subterranean or semi-subterranean masonry chamber entered via a wooden ladder through a central roof hatchway:

• Evolving architecturally from earlier Basketmaker III domestic pit houses, every kiva contains a central firepit, a fresh-air ventilator shaft separated from the firepit by an upright stone deflector slab, masonry pilasters supporting a cribbed log roof, a surrounding bench (banquette), and a small circular hole in the floor north of the hearth—the sipapu—symbolizing the sacred portal of emergence through which the ancestors climbed from the lower worlds into the present Fourth World.

Following a pronounced 50-year drought in 1130–1180 CE that ended monumental construction in Chaco Canyon (shifting the regional center briefly north to Aztec Ruins on the Animas River), Pueblo III communities (~1150–1300 CE) aggregated into large, defensible towns in the Mesa Verde region of southwestern Colorado:

• Including giant canyon-head and open-air villages (Yellow Jacket Pueblo with 1,200 rooms and 195 kivas; Sand Canyon Pueblo; and the multi-story towers of Hovenweep) and, during the final century (1200–1280 CE), approximately 600 overhanging sandstone alcove cliff dwellings at Mesa Verde—led by Cliff Palace (150 rooms and 23 kivas), Long House, Spruce Tree House, and Balcony House.
• Between 1276 and 1299 CE, tree-ring chronologies document the 24-year "Great Drought" accompanied by a breakdown of the summer monsoon and a cooling onset of the Little Ice Age that shortened the high-altitude growing season on the 2,100-meter Mesa Verde plateau. By 1300 CE, the entire Four Corners region was systematically depopulated as thousands of Ancestral Puebloan families carried their sacred clan lineages southward and eastward into the perennially watered Rio Grande Valley, Acoma ("Sky City"), Zuni (Halona:wa), and the spring-fed Hopi Mesas of Arizona.

1. Kidder, A. V. (1927). Southwestern archeological conference. Science, 66(1716), 489–491. https://doi.org/10.1126/science.66.1716.489
2. English, N. B., Betancourt, J. L., Dean, J. S., & Quade, J. (2001). Strontium isotopes reveal distant sources of architectural timber in Chaco Canyon, New Mexico. Proceedings of the National Academy of Sciences, 98(21), 11891–11896. https://doi.org/10.1073/pnas.211305498
3. Crown, P. L., & Hurst, W. J. (2009). Evidence of cacao use in the Prehispanic American Southwest. Proceedings of the National Academy of Sciences, 106(7), 2110–2113. https://doi.org/10.1073/pnas.0812817106
4. Kennett, D. J., Plog, S., George, R. J., Culleton, B. J., Watson, A. S., Skoglund, P., ... & Perry, G. H. (2017). Archaeogenomic evidence reveals prehistoric matrilineal dynasty. Nature Communications, 8, 14115. https://doi.org/10.1038/ncomms14115