Biology subjects

Hadden, C. S.

Publications and source records attributed to Hadden, C. S..

3 recordsLinked to original sources

bioRxiv2026

Subsistence transition preceded population turnover in the eastern Colombian Andes

Northwest South America was a pivotal region for human dispersals and cultural exchange during the Holocene. The Altiplano Cundiboyacense, a high-altitude plateau in the Eastern Cordillera of the Northern Andes of Colombia, preserves one of the most continuous archaeological sequences in the Americas, spanning from late Pleistocene hunter-gatherer groups to final late Holocene Muisca chiefdoms. Increasing the regional ancient DNA sample size 11-fold, we report genome-wide data from 209 individuals who lived over a period of more than 7000 years. This includes hunter-gatherers from the early-middle (10,000-7000 BP) and middle (7000-4000 BP) Holocene, initial late Holocene people (4000-2500 BP) who have the first isotopic evidence of C-enriched diets (attributed to maize), and populations associated with increasing sedentism and food production in the Herrera (2200-1300 BP) and Muisca (1200-500 BP) Periods. Previous work identified a major population turnover distinguishing earlier groups from Herrera-Muisca Period populations, but the absence of individuals dating 6000-2000 BP in that study left unresolved whether this ancestry shift was gradual or abrupt and whether it accompanied the earliest isotopic evidence of dietary input from maize or coincided with the later emergence of Herrera culture. We show that individuals predating the Herrera Period form a lineage that persisted for over five millennia, with population structure driven by drift in small groups and no detectable external gene flow. Two individuals who lived [~]2800 years ago - one directly dated to 983-835 calBCE - exhibit genetic profiles entirely consistent with hunter-gatherer ancestry yet have isotopic values consistent with the incorporation of maize into their diets, indicating subsistence change without population replacement. The emergence of Herrera culture [~]2200 BP coincided with a sharp genetic break, reflecting the migration of people carrying ancestry diverged by up to ten millennia into the Sabana de Bogota and displacing previously established peoples. By co-analyzing ancient data with modern Native Americans, we show these later populations derived from a mixture [~]4000 years ago of groups related to Chibchan language speakers of lower Central America and ones related to present-day people at the Amazonian-Andean interface who may have lived along the Chibchan expansion route. In the Herrera and Muisca Periods, genetic substructure distinguishes people from the southern and northern Altiplano, consistent with the cultural differentiation of these regions in the archaeological record. IN BRIEFAncient DNA data from the eastern Colombian Andes reveal five millennia of population continuity during which C plants were incorporated into subsistence systems without population replacement, followed later by a major ancestry turnover involving a population with ancestry admixed between that found in Chibchan-related groups and at the Amazonian-Andean interface.

genetics↗

bioRxiv2021

A Multi-proxy assessment of the impact of climate change on Late Holocene (ca 4500-3800 BP) Native American villages of the Georgia coast

Circular shell rings along the Atlantic Coast of southeastern North America are the remnants of some of the earliest villages that emerged during the Late Archaic Period (5000 - 3000 BP). Many of these villages, however, were abandoned during the Terminal Late Archaic Period (ca 3800 - 3000 BP). Here, we combine Bayesian chronological modeling with multiple environmental proxies to understand the nature and timing of environmental change associated with the emergence and abandonment of shell ring villages on Sapleo Island, Georgia. Our Bayesian models indicate that Native Americans occupied the three Sapelo shell rings at varying times with some generational overlap. By the end of the complexs occupation, only Ring III was occupied before abandonment ca. 3845 BP. Ring III also consists of statistically smaller oysters (Crassostrea virginica) that people harvested from less saline estuaries compared to earlier occupations. These data, when integrated with recent tree ring analyses, show a clear pattern of environmental instability throughout the period in which the rings were occupied. We argue that as the climate became unstable around 4300 BP, aggregation at shell ring villages provided a way to effectively manage fisheries that are highly sensitive to environmental change. However, with the eventual collapse of oyster fisheries and subsequent rebound in environmental conditions ca. 3800 BP, people dispersed from shell rings, and shifted to non-marine subsistence economies and other types of settlements. This study provides the most comprehensive evidence correlations between large-scale environmental change and societal transformations on the Georgia coast during the Late Archaic period.

ecology↗

bioRxiv2021

Social stratification without genetic differentiation at the site of Kulubnarti in Christian Period Nubia

Nubia has been a corridor for the movement of goods, culture, and people between sub-Saharan Africa, Egypt, and West Eurasia since prehistory, but little is known about the genetic landscape of the region prior to the influence of the Islamic migrations that began in the late 1st millennium CE. We report genome-wide data for 66 individuals from the site of Kulubnarti ([~]650-1000 CE), increasing the number of ancient individuals with genome-level data from the Nile Valley from three to 69. Our results shed light on the genetic ancestry of a Christian Period group and help to address a long-standing question about the relationships among people buried in two neighboring cemeteries who show skeletal evidence of differences in morbidity and mortality that are broadly suggestive of differences in social status. We find that the Kulubnarti Nubians were admixed with [~]43% Nilotic-related ancestry on average (individual proportions varied between [~]36-54%) and the remaining ancestry reflecting a West Eurasian-related gene pool likely introduced into Nubia through Egypt, but ultimately deriving from an ancestry pool like that found in the Bronze and Iron Age Levant. The admixed ancestry at Kulubnarti reflects interactions between genetically-distinct people in northeast Africa spanning almost a millennium, with West Eurasian ancestry disproportionately associated with females, highlighting the impact of female mobility in this region. We find no significant differences in ancestry among individuals from the two plausibly socially-stratified cemeteries at Kulubnarti, supporting hypotheses that the groups may have been socially divided but were not genetically distinct. We identify seven pairs of inter-cemetery relatives as close as second-degree, suggesting that any social divisions at Kulubnarti did not prevent mixing between groups. Present-day Nubians are not directly descended from the Christian Period people from Kulubnarti without additional admixture, attesting to the dynamic history of interaction that continues to shape the cultural and genetic landscape of Nubia.

genomics↗