Preceramic maize from Paredones and Huaca Prieta, Peru

Abstract

Maize (Zea mays ssp. mays) is among the world's most important and ancient domesticated crops. Although the chronology of its domestication and initial dispersals out of Mexico into Central and South America has become more clear due to molecular and multiproxy archaeobotanical research, important problems remain. Among them is the paucity of information on maize's early morphological evolution and racial diversification brought about in part by the poor preservation of macrofossils dating to the pre-5000 calibrated years before the present period from obligate dispersal routes located in the tropical forest. We report newly discovered macrobotanical and microbotanical remains of maize that shed significant light on the chronology, land race evolution, and cultural contexts associated with the crop's early movements into South America and adaptation to new environments. The evidence comes from the coastal Peruvian sites of Paredones and Huaca Prieta, Peru; dates from the middle and late preceramic and early ceramic periods (between ca. 6700 and 3000 calibrated years before the present); and constitutes some of the earliest known cobs, husks, stalks, and tassels. The macrobotanical record indicates that a diversity of racial complexes characteristic of the Andean region emerged during the preceramic era. In addition, accelerator mass spectrometry radiocarbon determinations carried out directly on different structures of preserved maize plants strongly suggest that assays on burned cobs are more reliable than those on unburned cobs. Our findings contribute to knowledge of the early diffusion of maize and agriculture and have broader implications for understanding the development of early preindustrial human societies.early crops | social complexity G enetic and archaeological data indicate that corn or maize (Zea mays ssp. mays) was domesticated in Mexico by ∼8700 calibrated years before the present (cal BP) (1-4). It then spread into other tropical regions in and south of Mexico in the following millennia (5-13). In South America, preceramic-aged microfossils such as starch grains and phytoliths are reported from southwest Ecuador by ∼7000-5500 cal BP (11-13); in the southern Andean highlands, by 4000 cal BP (14); and in southeastern South America, by 4500 cal BP (15). Macrofossils (cobs and kernels) have been recovered from a number of archaeological sites in the Andean region, yet none have produced secure accelerator mass spectrometry (AMS) age determinations before ∼3800 cal BP (7).We report here 293 newly excavated macrofossils of popcorn and flour corn remains; 15 radiocarbon ages directly determined from these fossils; and maize phytoliths and starch grains from deep, undisturbed stratigraphic contexts AMS-dated as early as 6775-6504 cal BP at the sites of Paredones and Huaca Prieta on the north coast of Peru (Fig. 1) (dates on maize from the sites are given in 2σ-calibrated age ranges). Our data appear to document the chronological development and use of early landraces of maize at these sites.Huaca Priet...

Independent Molecular Basis of Convergent Highland Adaptation in Maize

“…Pairwise F ST among populations reveals low overall differentiation (Table 1), and the higher F ST values observed in South America are consistent with the decreased admixture seen in STRUCTURE. Archaeological evidence supports a more recent colonization of the highlands in South America (Perry et al 2006;Piperno 2006;Grobman et al 2012), suggesting that the observed differentiation may be the result of a stronger bottleneck during colonization of the South American highlands. …”

“…N A was set to 150,000, using estimates of the composite parameter 4N A m $ 0:018 from parviglumis (Eyre-Walker et al Grobman et al 2012) and estimated the remaining four parameters (a, b 1 ; b 2 ; and g).…”

Late Archaic–Early Formative period microbotanical evidence for potato at Jiskairumoko in the Titicaca Basin of southern Peru

“…Accordingly, beginning in the 1960s, Andeanists Towle (8) and Ugent et al (9,10) sought to further their insights through microbotanical analysis of starch morphology from macrogeophytes. Their pioneering work foreshadowed the mounting role of microbotanical studies around the world, including the study area (11)(12)(13)(14)(15)(16)(17)(18). Following suit, this study contributes direct microbotanical evidence for potato within its botanical hearth at the onset of food production.…”

La milpa del occidente de Mesoamérica: profundidad histórica, dinámica evolutiva y rutas de dispersión a Suramérica

“…Más hacia el sur, la ruta pudo haber sido por la costa sur de Ecuador y el norte de Perú (Dillehay, Rossen, Maggard, Stackelbeck, & Netherly, 2003;Stothert, et al, 2003;Pearsall, Chandler-Ezell, K. & Chandler-Ezell, A. 2004;Grobman et al, 2012). La difusión hacia Brasil se ha planteado a través de dos rutas: una por el sur, cruzando Los Andes hacia el suroeste de Brasil y noroeste de Bolivia y otra por el norte, siguiendo el río Orinoco y el río Amazonas (Freitas, Bendel, Allaby, & Brown, 2003) (Figura 1).…”

“…Los registros arqueo-botánicos de granos de almidón y fitolitos de maíz asociados a las piedras moledoras, sugieren esta ruta e indican el arribo del maíz a Panamá tan temprano como hace 7,400 años AP, a la costa norte de Suramérica entre 7,900-7,670 AP., al valle medio del río Cauca en Colombia entre 7,000-6,500 AP., y a la costa sur de Ecuador y norte del Perú entre 6,700-6,500 AP (Dickau, Ranere & Cooke, 2007;Zarrillo, et al, 2008;Grobman et al, 2012;Aceituno & Loaiza, 2014) …”