skip to main content

Search for: All records

Creators/Authors contains: "Kennett, Douglas J."

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. The origins of maize were the topic of vigorous debate for nearly a century, but neither the current genetic model nor earlier archaeological models account for the totality of available data, and recent work has highlighted the potential contribution of a wild relative,Zea maysssp.mexicana. Our population genetic analysis reveals that the origin of modern maize can be traced to an admixture between ancient maize andZea maysssp.mexicanain the highlands of Mexico some 4000 years after domestication began. We show that variation in admixture is a key component of maize diversity, both at individual loci and for additive genetic variation underlying agronomic traits. Our results clarify the origin of modern maize and raise new questions about the anthropogenic mechanisms underlying dispersal throughout the Americas.

    more » « less
    Free, publicly-accessible full text available December 1, 2024
  2. Accelerator mass spectrometry radiocarbon (AMS 14C) dates ( n = 78) from human bone collagen were analyzed in the largest high-resolution chronology study to date at the ancient city of Teotihuacan in central Mexico (ca. AD 1–550). Samples originate from the residential neighborhood of La Ventilla, located in the heart of this major urban center. Here, a trapezoidal model using Bayesian statistics is built from 14C dates combined with data derived from the stylistic analysis of ceramics from burial contexts. Based on this model, we suggest possible refinements to Teotihuacan’s ceramic chronology, at least within the La Ventilla neighborhood. We also explore the abandonment and reoccupation of La Ventilla after the political collapse of Teotihuacan in the Metepec and Coyotlatelco phases. Findings suggest that these ceramic phases began earlier than is currently projected and that the well-documented abandonment period of La Ventilla may have occurred more abruptly than originally estimated. 
    more » « less
  3. Abstract People could have hunted Madagascar’s megafauna to extinction, particularly when introduced taxa and drought exacerbated the effects of predation. However, such explanations are difficult to test due to the scarcity of individual sites with unambiguous traces of humans, introduced taxa, and endemic megaherbivores. We excavated three coastal ponds in arid SW Madagascar and present a unique combination of traces of human activity (modified pygmy hippo bone, processed estuarine shell and fish bone, and charcoal), along with bones of extinct megafauna (giant tortoises, pygmy hippos, and elephant birds), extirpated fauna (e.g., crocodiles), and introduced vertebrates (e.g., zebu cattle). The disappearance of megafauna from the study sites at ~ 1000 years ago followed a relatively arid interval and closely coincides with increasingly frequent traces of human foraging, fire, and pastoralism. Our analyses fail to document drought-associated extirpation or multiple millennia of megafauna hunting and suggest that a late combination of hunting, forest clearance, and pastoralism drove extirpations. 
    more » « less
  4. Revisamos la antigüedad y el carácter tipológico de la cerámica conocida como “Pox Pottery”. Ésta fue descrita con base en un atributo específico reportado en la década de 1960 por Charles Brush, quien lo consideró particularmente temprano (~2440 aC). Excavaciones en los mismos sitios de la costa de Guerrero donde Brush trabajó permitieron recuperar cerámica del periodo Formativo Temprano y mostraba las características “pox”. Aquí reportamos las frecuencias de fragmentos cerámicos de esos depósitos, de acuerdo con las tipologías regionales establecidas, y reportamos fechas radiométricas (AMS 14 C) usadas para establecer una cronología estratigráfica Bayesiana para delimitar la edad de los depósitos en cada sitio. Proponemos que “Pox Pottery” no corresponde con un tipo cerámico per se, y que el atributo “pox” ocurre en varios tipos cerámicos del Formativo Temprano. Ésta es similar a las tradiciones rojo sobre bayo que se desarrollaron temprano en las tierras altas del centro de México y al occidente del Istmo de Tehuantepec. Nuestro refinamiento cronológico demuestra que esta cerámica data entre 1820 y 1400 cal aC. Es consistente con estudios recientes que indican una edad similar para las cerámicas rojo sobre bayo, sugiriendo la existencia de tradiciones culturales diferentes al complejo Locona que emergió paralelamente. 
    more » « less
  5. Abstract The genetic prehistory of human populations in Central America is largely unexplored leaving an important gap in our knowledge of the global expansion of humans. We report genome-wide ancient DNA data for a transect of twenty individuals from two Belize rock-shelters dating between 9,600-3,700 calibrated radiocarbon years before present (cal. BP). The oldest individuals (9,600-7,300 cal. BP) descend from an Early Holocene Native American lineage with only distant relatedness to present-day Mesoamericans, including Mayan-speaking populations. After ~5,600 cal. BP a previously unknown human dispersal from the south made a major demographic impact on the region, contributing more than 50% of the ancestry of all later individuals. This new ancestry derived from a source related to present-day Chibchan speakers living from Costa Rica to Colombia. Its arrival corresponds to the first clear evidence for forest clearing and maize horticulture in what later became the Maya region. 
    more » « less
  6. Abstract Data from rock shelters in southern Belize show evidence of tool making, hunting, and aquatic resource exploitation by 10,500 cal b.c. ; the shelters functioned as mortuary sites between 7600 and 2000 cal b.c. Early Holocene contexts contain stemmed and barbed bifaces as part of a tradition found broadly throughout the neotropics. After around 6000 cal b.c. , bifacial tools largely disappear from the record, likely reflecting a shift to increasing reliance on plant foods, around the same time that the earliest domesticates appear in the archaeological record in the neotropics. We suggest that people living in southern Belize maintained close ties with neighbors to the south during the Early Holocene, but lagged behind in innovating new crops and farming technologies during the Middle Holocene. Maize farming in Belize intensified between 2750–2050 cal b.c. as maize became a dietary staple, 1000–1300 years later than in South America. Overall, we argue from multiple lines of data that the Neotropics of Central and South America were an area of shared information and technologies that heavily influenced cultural developments in southeastern Mesoamerica during the Early and Middle Holocene. 
    more » « less
  7. Introduced predators currently threaten endemic animals on Madagascar through predation, facilitation of human-led hunts, competition, and disease transmission, but the antiquity and past consequences of these introductions are poorly known. We use directly radiocarbon dated bones of introduced dogs ( Canis familiaris ) to test whether dogs could have aided human-led hunts of the island’s extinct megafauna. We compare carbon and nitrogen isotope data from the bone collagen of dogs and endemic “fosa” ( Cryptoprocta spp.) in central and southwestern Madagascar to test for competition between introduced and endemic predators. The distinct isotopic niches of dogs and fosa suggest that any past antagonistic relationship between these predators did not follow from predation or competition for shared prey. Radiocarbon dates confirm that dogs have been present on Madagascar for over a millennium and suggest that they at least briefly co-occurred with the island’s extinct megafauna, which included giant lemurs, elephant birds, and pygmy hippopotamuses. Today, dogs share a mutualism with pastoralists who also occasionally hunt endemic vertebrates, and similar behavior is reflected in deposits at several Malagasy paleontological sites that contain dog and livestock bones along with butchered bones of extinct megafauna and extant lemurs. Dogs on Madagascar have had a wide range of diets during the past millennium, but relatively high stable carbon isotope values suggest few individuals relied primarily on forest bushmeat. Our newly generated data suggest that dogs were part of a suite of animal introductions beginning over a millennium ago that coincided with widespread landscape transformation and megafaunal extinction. 
    more » « less
  8. null (Ed.)
    El cambio de la recolección de moluscos a la pesca como una estrategia primaria de forrajear costero pueda permitir las cazadores-recolectores a obtener más comida y asentar con poblaciones más altas. En las islas Channel más norteñas de California (NCI), después el desarrollo de los anzuelos hechos de piezas individuales de concha cerca de 2500 años calibrados ante de presente (cal BP), la dieta expandía de moluscos ante todo a incluir peces de cerca de la orilla en cantidades mayores. Durante la anomalía climática medieval (1150–600 cal BP), asentamiento en las islas condensaba a una cantidad pequeña de pueblos costales grandes con poblaciones de alta densidad apoyados por especies de pez de cerca de la orilla incluso de los rocotes, las mojarras y las señoritas. Datos faunales de cinco sitios de la región oeste de la Isla Santa Rosa (CA-SRI-15, -31, -97, -313 y -333) demuestran un aumento en la pesca cerca de la orilla a través del tiempo. Discutimos que cambios demográficos que ocurrían en la NCI eran acompañados por cambios en las estrategias subsistencias relacionadas en parte al riesgo de el fracaso cuando intentar a obtener recursos diferentes. Mientras la densidad de población aumentaba, la estrategia de bajo riesgo de cosechar los moluscos declinaba en importancia relativa y la estrategia del riesgo alto de la pesca cerca de la orilla aumentaba. Aunque ejemplos de múltiples estrategias de subsistencia simultáneos en comunidades de cazadores-recolectores están presentes en el registro etnográfico, este estudio proporciona una estructura a observar patrones semejantes en el registro arqueológico. 
    more » « less
  9. Abstract Objectives

    We leverage recent bioarchaeological approaches and life history theory to address the implications of the osteological paradox in a study population. The goal of this article is to evaluate morbidity and mortality patterns as well as variability in the risk of disease and death during the Late Intermediate period (LIP; 950–1450 C.E.) in the Nasca highlands of Peru. We demonstrate how the concurrent use of multiple analytical techniques and life history theory can engage the osteological paradox and provide salient insights into the study of stress, frailty, and resilience in past populations.

    Materials and methods

    Crania from LIP burial contexts in the Nasca highlands were examined for cribra orbitalia (n = 325) and porotic hyperostosis (n = 270). All age groups and both sexes are represented in the sample. Survivor/nonsurvivor analysis assessed demographic differences in lesion frequency and severity. Hazard models were generated to assess differences in survivorship. The relationship between dietary diversity and heterogeneity in morbidity was assessed using stable δ15N and δ13C isotope values for bone collagen and carbonate. One hundred and twenty‐four crania were directly AMS radiocarbon dated, allowing for a diachronic analysis of morbidity and mortality.


    The frequency and expression of both orbital and vault lesions increases significantly during the LIP. Survivor/nonsurvivor analysis indicates cranial lesions co‐vary with frailty rather than robusticity or longevity. Hazard models show (1) decreasing survivorship with the transition into the LIP, (2) significantly lower adult life expectancy for females compared to males, and (3) individuals with cranial lesions have lower survivorship across the life course. Stable isotope results show very little dietary diversity. Mortality risk and frequency of pathological skeletal lesions were highest during Phase III (1300–1450 C.E.) of the LIP.


    Results provide compelling evidence of increasing physiological stress and mortality in the Nasca highlands during the LIP, but also reveal substantial heterogeneity in frailty and the risk of death. Certain members of society experienced a heavier disease burden and higher mortality compared to their contemporaries. Elevated levels of disease and lethal trauma among females account for some of the sex differences in survivorship but cannot explain the large degree of female‐biased mortality. We hypothesize that parental investment in males or increased female fertility rates may explain these differences.

    more » « less
  10. Abstract

    The influence of climate change on civil conflict and societal instability in the premodern world is a subject of much debate, in part because of the limited temporal or disciplinary scope of case studies. We present a transdisciplinary case study that combines archeological, historical, and paleoclimate datasets to explore the dynamic, shifting relationships among climate change, civil conflict, and political collapse at Mayapan, the largest Postclassic Maya capital of the Yucatán Peninsula in the thirteenth and fourteenth centuries CE. Multiple data sources indicate that civil conflict increased significantly and generalized linear modeling correlates strife in the city with drought conditions between 1400 and 1450 cal. CE. We argue that prolonged drought escalated rival factional tensions, but subsequent adaptations reveal regional-scale resiliency, ensuring that Maya political and economic structures endured until European contact in the early sixteenth century CE.

    more » « less