Archaeological Central American maize genomes suggest ancient gene flow from South America

Maize (Zea mays ssp. mays) domestication began in southwestern Mexico ∼9,000 calendar years before present (cal. BP) and humans dispersed this important grain to South America by at least 7,000 cal. BP as a partial domesticate. South America served as a secondary improvement center where the domestication syndrome became fixed and new lineages emerged in parallel with similar processes in Mesoamerica. Later, Indigenous cultivators carried a second major wave of maize southward from Mesoamerica, but it has been unclear until now whether the deeply divergent maize lineages underwent any subsequent gene flow between these regions. Here we report ancient maize genomes (2,300–1,900 cal. BP) from El Gigante rock shelter, Honduras, that are closely related to ancient and modern maize from South America. Our findings suggest that the second wave of maize brought into South America hybridized with long-established landraces from the first wave, and that some of the resulting newly admixed lineages were then reintroduced to Central America. Direct radiocarbon dates and cob morphological data from the rock shelter suggest that more productive maize varieties developed between 4,300 and 2,500 cal. BP. We hypothesize that the influx of maize from South America into Central America may have been an important source of genetic diversity as maize was becoming a staple grain in Central and Mesoamerica

FARMING AND CATASTROPHE AT LA JOYA: A CONSIDERATION OF AGRICULTURAL INTENSIFICATION AND RISK IN THE FORMATIVE SIERRA DE LOS TUXTLAS (Agricultura y catástrofe en La Joya: un examen de la intensificación agrícola y riesgo en el período Formativo de la Sierra de los Tuxtlas)

This paper examines the process of agricultural intensification as it occurred during the Formative period (1400 BC-AD 300) along the southern Gulf Coast of Mexico. Over the course of two millennia, rural villagers living in the Olmec hinterland of the Sierra de los Tuxtlas invested more time and labor into farming activities as they became increasingly sedentary and dealt with episodic volcanic eruptions and ash fall. This period of time witnessed the development of a regional political hierarchy in the Tuxtlas, which also had consequences for village-level subsistence. In examining agricultural intensification in the context of volcanic catastrophe and political development, I analyze archaeological plant and animal data from the site of La Joya, a farming village located in southern Veracruz, Mexico spanning the Formative period. The subsistence data indicate that maize intensification was a long, incremental process that began in the Middle Formative period, hundreds of years before political development and the establishment of a regional center. At the close of the Late Formative period, after the region's political consolidation, a severe volcanic eruption blanketed the region with ash, leading to significant, if temporary, environmental circumscription. La Joya villagers responded to this catastrophe by intensifying maize production on infields and expanding their hunting and fishing territories to exploit a wider range of animal prey. ESPAÑOL: Este estudio examina el proceso de sedentarización, intensificación agrícola y desarrollo de una jerarquía política regional durante el período Formativo (1400 a. C.-300 d. C.) a lo largo de la costa meridional del Golfo de México, en la zona olmeca de la Sierra de los Tuxtlas. Los resultados obtenidos analizando los datos de animales y plantas provenientes del sitio de La Joya, un pueblo agrícola ubicado en el sur de Veracruz (México) que abarca todo el Formativo, indican que la intensificación del maíz fue un proceso largo y gradual que se inició en la fase media de esta etapa, cientos de años antes del establecimiento de un centro regional. A finales del Formativo Tardío, después de su consolidación política, una severa erupción volcánica cubrió con ceniza la región. Los aldeanos de La Joya respondieron a esta catástrofe incrementando la producción de maíz en las inmediaciones y ampliando sus territorios de caza y pesca para explotar una gama más amplia de animales

Paleoethnobotany and Ancient Alcohol Production: A Mini-Review

The production and consumption of alcoholic beverages in the past is an important consideration when addressing issues involving ancient food. However, successfully demonstrating that alcoholic beverages were produced in prehistoric contexts is problematic.  As a result, archaeobotanists have developed a multi-scalar approach, incorporating multiple lines of evidence, to argue for the production of fermented beverages in the past.</p

High-precision chronology for Central American maize diversification from El Gigante rockshelter, Honduras

The first steps toward maize (Zea mays subspecies mays) domestication occurred in the Balsas region of Mexico by ∼9,000 calendar years B.P. (cal B.P.), but it remains unclear when maize was productive enough to be a staple grain in the Americas. Molecular and microbotanical data provide a partial picture of the timing and nature of morphological change, with genetic data indicating that alleles for some domestication traits were not yet fixed by 5,300 cal B.P. in the highlands of Mexico. Here, we report 88 radiocarbon dates on the botanical remains from El Gigante rockshelter (Honduras) to establish a Bayesian chronology over the past ∼11,000 y spanning the transition to maize-based food production. Botanical remains are remarkably well preserved and include over 10,000 maize macrofossils. We directly dated 37 maize cobs to establish the appearance and local change of maize at the site. Cobs are common in deposits dating between 4,340 and 4,020 cal B.P., and again between 2,350 and 980 cal B.P. The earliest cobs appear robustly domesticated, having 10–14 rows, suggesting strong selection for increased yield. The later cobs are comparable to these earliest ones, but show clear emergence of diverse traits, including increased cob width, rachis segment length, and cupule width. Our results indicate that domesticated landraces of maize productive enough to be a staple grain existed in Central America by 4,300 cal B.P

High-precision chronology for Central American maize diversification from El Gigante rockshelter, Honduras

The first steps toward maize (Zea mays subspecies mays) domestication occurred in the Balsas region of Mexico by ∼9,000 calendar years B.P. (cal B.P.), but it remains unclear when maize was productive enough to be a staple grain in the Americas. Molecular and microbotanical data provide a partial picture of the timing and nature of morphological change, with genetic data indicating that alleles for some domestication traits were not yet fixed by 5,300 cal B.P. in the highlands of Mexico. Here, we report 88 radiocarbon dates on the botanical remains from El Gigante rockshelter (Honduras) to establish a Bayesian chronology over the past ∼11,000 y spanning the transition to maize-based food production. Botanical remains are remarkably well preserved and include over 10,000 maize macrofossils. We directly dated 37 maize cobs to establish the appearance and local change of maize at the site. Cobs are common in deposits dating between 4,340 and 4,020 cal B.P., and again between 2,350 and 980 cal B.P. The earliest cobs appear robustly domesticated, having 10-14 rows, suggesting strong selection for increased yield. The later cobs are comparable to these earliest ones, but show clear emergence of diverse traits, including increased cob width, rachis segment length, and cupule width. Our results indicate that domesticated landraces of maize productive enough to be a staple grain existed in Central America by 4,300 cal B.P

Data for Archaeological Central American maize genomes suggest ancient gene flow from South America

Maize (Zea mays ssp. mays) domestication began in southwestern Mexico ~9,000 calendar years before present (cal. BP) and humans dispersed this important grain to South America by at least 7000 cal. BP as a partial domesticate. South America served as a secondary improvement center where the domestication syndrome became fixed and new lineages emerged in parallel with similar processes in Mesoamerica. Later, Indigenous cultivators carried a second major wave of maize southward from Mesoamerica, but it has been unclear until now whether the deeply divergent maize lineages underwent any subsequent gene flow between these regions. Here we report ancient maize genomes (2,300-1,900 cal. BP) from El Gigante rock-shelter, Honduras, that are closely related to ancient and modern maize from South America. Our findings suggest that the second wave of maize brought into South America hybridized with long-established landraces from the first wave, and that some of the resulting newly admixed lineages were then reintroduced to Central America. Direct radiocarbon dates and cob morphological data from the rock-shelter suggest that more productive maize varieties developed between 4,300 and 2,500 cal. BP. We hypothesize that the influx of maize from South America into Central America may have been an important source of genetic diversity as maize was becoming a staple grain in Central and Mesoamerica