Papers by Elizabeth Sawchuk
American Journal of Human Genetics, 2024
Population history-focused DNA and ancient DNA (aDNA) research in Africa has dramatically increas... more Population history-focused DNA and ancient DNA (aDNA) research in Africa has dramatically increased in the past decade, enabling increasingly fine-scale investigations into the continent's past. However, while international interest in human genomics research in Africa grows, major structural barriers limit the ability of African scholars to lead and engage in such research and impede local communities from partnering with researchers and benefitting from research outcomes. Because conversations about research on African people and their past are often held outside Africa and exclude African voices, an important step for African DNA and aDNA research is moving these conversations to the continent. In May 2023 we held the DNAirobi workshop in Nairobi, Kenya and here we synthesize what emerged most prominently in our discussions. We propose an ideal vision for population history-focused DNA and aDNA research in Africa in ten years' time and acknowledge that to realize this future, we need to chart a path connecting a series of ''landmarks'' that represent points of consensus in our discussions. These include effective communication across multiple audiences, reframed relationships and capacity building, and action toward structural changes that support science and beyond. We concluded there is no single path to creating an equitable and self-sustaining research ecosystem, but rather many possible routes linking these landmarks. Here we share our diverse perspectives as geneticists, anthropologists, archaeologists, museum curators, and educators to articulate challenges and opportunities for African DNA and aDNA research and share an initial map toward a more inclusive and equitable future.
Bookmarks Related papers MentionsView impact
Proceedings of the Royal Society B, 2024
The histories of African crops remain poorly understood despite their contemporary importance. In... more The histories of African crops remain poorly understood despite their contemporary importance. Integration of crops from western, eastern and northern Africa probably first occurred in the Great Lakes Region of eastern Africa; however, little is known about when and how these agricultural systems coalesced. This article presents archaeobotanical analyses from an approximately 9000-year archaeological sequence at Kakapel Rockshelter in western Kenya, comprising the largest and most extensively dated archaeobotanical record from the interior of equatorial eastern Africa. Direct radiocarbon dates on carbonized seeds document the presence of the West African crop cowpea (Vigna unguiculata (L.) Walp) approximately 2300 years ago, synchronic with the earliest date for domesticated cattle (Bos taurus). Peas (Pisum sativum L. or Pisum abyssinicum A. Braun) and sorghum (Sorghum bicolor (L.) Moench) from the northeast and eastern African finger millet (Eleusine coracana (L.) Gaertn.) are incorporated later, by at least 1000 years ago. Combined with ancient DNA evidence from Kakapel and the surrounding region, these data support a scenario in which the use of diverse domesticated species in eastern Africa changed over time rather than arriving and being maintained as a single package. Findings highlight the importance of local heterogeneity in shaping the spread of food production in sub-Saharan Africa
Bookmarks Related papers MentionsView impact
African Archaeological Review, 2023
Gishimangeda Cave, near Lake Eyasi in northern Tanzania, exemplifies many challenges inherent in ... more Gishimangeda Cave, near Lake Eyasi in northern Tanzania, exemplifies many challenges inherent in studying poorly documented "legacy collections" in African archaeology. The archaeological assemblage of at least twelve human individuals and associated artifacts was excavated in 1967 for primarily physical anthropological purposes. However, it has been difficult to link the materials to archaeological contexts or chronology. Recently, ancient DNA analysis of eleven individuals, eight of whom
Bookmarks Related papers MentionsView impact
Antiquity, 2022
The megalithic pillar sites found around Lake Turkana, Kenya, are monumental cemeteries built app... more The megalithic pillar sites found around Lake Turkana, Kenya, are monumental cemeteries built approximately 5000 years ago. Their construction coincides with the spread of pastoralism into the region during a period of profound climate change. Early work at the Jarigole pillar site suggested that these places were secondary burial grounds. Subsequent excavations at other pillar sites, however, have revealed planned mortuary cavities for predominantly primary burials, challenging the idea that all pillar sites belonged to a single 'Jarigole mortuary tradition'. Here, the authors report new findings from the Jarigole site that resolve long-standing questions about eastern Africa's earliest monuments and provide insight into the social lives, and deaths, of the region's first pastoralists.
Bookmarks Related papers MentionsView impact
Ancient DNA and deep population structure in sub-Saharan African foragers, 2022
Bookmarks Related papers MentionsView impact
Nature Briefings, 2022
Archaeologists have various hypotheses for how populations changed in Africa about 50,000 years a... more Archaeologists have various hypotheses for how populations changed in Africa about 50,000 years ago, during the Later Stone Age transition. Now, the earliest available ancient-DNA sequences from sub-Saharan Africa reveal a complex Late Pleistocene population structure, pointing to large shifts in human movement and in patterns of social interaction.
Bookmarks Related papers MentionsView impact
by Elizabeth Sawchuk, Kathryn de Luna, John Arthur, Alex Bertacchi, Jessica Inés Cerezo-Román, Potiphar Kaliba, Maggie Katongo, Myra Laird, Jason E Lewis, Audax Mabulla, George Mudenda, Christine Ogola, and Pamela R Willoughby Nature, 2022
Multiple lines of genetic and archaeological evidence suggest that there were major demographic c... more Multiple lines of genetic and archaeological evidence suggest that there were major demographic changes in the terminal Late Pleistocene epoch and early Holocene epoch of sub-Saharan Africa1,2,3,4. Inferences about this period are challenging to make because demographic shifts in the past 5,000 years have obscured the structures of more ancient populations3,5. Here we present genome-wide ancient DNA data for six individuals from eastern and south-central Africa spanning the past approximately 18,000 years (doubling the time depth of sub-Saharan African ancient DNA), increase the data quality for 15 previously published ancient individuals and analyse these alongside data from 13 other published ancient individuals. The ancestry of the individuals in our study area can be modelled as a geographically structured mixture of three highly divergent source populations, probably reflecting Pleistocene interactions around 80–20 thousand years ago, including deeply diverged eastern and southern African lineages, plus a previously unappreciated ubiquitous distribution of ancestry that occurs in highest proportion today in central African rainforest hunter-gatherers. Once established, this structure remained highly stable, with limited long-range gene flow. These results provide a new line of genetic evidence in support of hypotheses that have emerged from archaeological analyses but remain contested, suggesting increasing regionalization at the end of the Pleistocene epoch.
Bookmarks Related papers MentionsView impact
The Encyclopedia of Ancient History, 2021
Bookmarks Related papers MentionsView impact
Nature, 2021
We are a group of archaeologists, anthropologists, curators and geneticists representing diverse ... more We are a group of archaeologists, anthropologists, curators and geneticists representing diverse global communities and 31 countries. All of us met in a virtual workshop dedicated to ethics in ancient DNA research held in November 2020. There was widespread agreement that globally applicable ethical guidelines are needed, but that recent recommendations grounded in discussion about research on human remains from North America are not always generalizable worldwide. Here we propose the following globally applicable guidelines, taking into consideration diverse contexts. These hold that: (1) researchers must ensure that all regulations were followed in the places where they work and from which the human remains derived; (2) researchers must prepare a detailed plan prior to beginning any study; (3)
Bookmarks Related papers MentionsView impact
Azania: Archaeological Research in Africa
Bookmarks Related papers MentionsView impact
Proceedings of the National Academy of Sciences of the United States of America, Sep 20, 2018
Monumental architecture is a prime indicator of social complexity, because it requires many peopl... more Monumental architecture is a prime indicator of social complexity, because it requires many people to build a conspicuous structure commemorating shared beliefs. Examining monumentality in different environmental and economic settings can reveal diverse reasons for people to form larger social units and express unity through architectural display. In multiple areas of Africa, monumentality developed as mobile herders created large cemeteries and practiced other forms of commemoration. The motives for such behavior in sparsely populated, unpredictable landscapes may differ from well-studied cases of monumentality in predictable environments with sedentary populations. Here we report excavations and ground-penetrating radar surveys at the earliest and most massive monumental site in eastern Africa. Lothagam North Pillar Site was a communal cemetery near Lake Turkana (northwest Kenya) constructed 5,000 years ago by eastern Africa's earliest pastoralists. Inside a platform ringed by...
Bookmarks Related papers MentionsView impact
American Journal of Physical Anthropology, 2021
Objectives: The Late Pleistocene and early Holocene in eastern Africa are associated with complex... more Objectives: The Late Pleistocene and early Holocene in eastern Africa are associated with complex evolutionary and demographic processes that contributed to the population variability observed in the region today. However, there are relatively few human skeletal remains from this time period. Here we describe six individuals from the Kisese II rockshelter in Tanzania that were excavated in 1956, present a radiocar-bon date for one of the individuals, and compare craniodental morphological diversity among eastern African populations. Materials and Methods: This study used standard biometric analyses to assess the age, sex, and stature of the Kisese II individuals. Eastern African craniodental morphological variation was assessed using measures of dental size and a subset of Howells' cranial measurements for the Kisese II individuals as well as early Holocene, early pas-toralist, Pastoral Neolithic, and modern African individuals. Results: Our results suggest a minimum of six individuals from the Kisese II collections with two adults and four juveniles. While the dating for most of the burials is uncertain, one individual is directly radiocarbon dated to 7.1 ka indicating that at least one burial is early Holocene in age. Craniodental metric comparisons indicate that the Kisese II individuals extend the amount of human morphological diversity among Holocene eastern Africans. Conclusions: Our findings contribute to a growing body of evidence that Late Pleis-tocene and early Holocene eastern Africans exhibited relatively high amounts of morphological diversity. However, the Kisese II individuals suggest morphological
Bookmarks Related papers MentionsView impact
Science Advances, 2020
Africa hosts the greatest human genetic diversity globally, but legacies of ancient population in... more Africa hosts the greatest human genetic diversity globally, but legacies of ancient population interactions and dispersals across the continent remain understudied. Here, we report genome-wide data from 20 ancient sub-Saharan African individuals, including the first reported ancient DNA from the DRC, Uganda, and Botswana. These data demonstrate the contraction of diverse, once contiguous hunter-gatherer populations, and suggest the resistance to interaction with incoming pastoralists of delayed-return foragers in aquatic environments. We refine models for the spread of food producers into eastern and southern Africa, demonstrating more complex trajectories of admixture than previously suggested. In Botswana, we show that Bantu ancestry post-dates admixture between pastoralists and foragers, suggesting an earlier spread of pastoralism than farming to southern Africa. Our findings demonstrate how processes of migration and admixture have markedly reshaped the genetic map of sub-Saharan Africa in the past few millennia and highlight the utility of combined archaeological and archaeogenetic approaches.
Bookmarks Related papers MentionsView impact
Nature, 2020
Our knowledge of ancient human population structure in sub-Saharan Africa, particularly prior to ... more Our knowledge of ancient human population structure in sub-Saharan Africa, particularly prior to the advent of food production, remains limited. Here we report genome-wide DNA data from four children—two of whom were buried approximately 8,000 years ago and two 3,000 years ago—from Shum Laka (Cameroon), one of the earliest known archaeological sites within the probable homeland of the Bantu language group1–11. One individual carried the deeply divergent Y chromosome haplogroup A00, which today is found almost exclusively in the same region12,13. However, the genome-wide ancestry profiles of all four individuals are most similar to those of present-day hunter-gatherers from western Central Africa, which implies that populations in western Cameroon today—as well as speakers of Bantu languages from across the continent—are not descended substantially from the population represented by these four people. We infer an Africa-wide phylogeny that features widespread admixture and three prominent radiations, including one that gave rise to at least four major lineages deep in the history of modern humans.
Bookmarks Related papers MentionsView impact
Palaeogeography, Palaeoclimatology, Palaeoecology, 2020
The ecological adaptations that stimulated the dispersal and technological strategies of our spec... more The ecological adaptations that stimulated the dispersal and technological strategies of our species during the Late Pleistocene remain hotly disputed, with some influential theories focusing on grassland biomes or marine resources as key drivers behind the rapid expansion and material culture innovations of Homo sapiens within and beyond Africa. Here, we present novel chronologically resolved, zooarchaeological taxonomic and taphonomic analysis, and stable isotope analysis of human and faunal tooth enamel, from the site of Panga ya Saidi (c. 78–0.4 ka), Kenya. Zooarchaeological data provide rare insights into the fauna associated with, and utilized by, Late Pleistocene-Holocene human populations in tropical coastal eastern Africa. Combined zooarchaeological and faunal stable isotope data provide some of the only dated, ‘on-site’ archives of palaeoenvironments beyond the arid interior of eastern Africa for this time period, while stable isotope analysis of humans provides direct snapshots of the dietary reliance of foragers at the site. Results demonstrate that humans consistently utilized tropical forest and grassland biomes throughout the period of site occupation, through a transition from Middle Stone Age to Later Stone Age technological industries and the arrival of agriculture in the region. By contrast, while coastal resources were obtained for use in symbolic material culture, there is limited evidence for con- sumption of marine resources until the Holocene. We argue that the ecotonal or heterogeneous environments of coastal eastern Africa may have represented an important refugium for populations during the increasing cli- matic variability of the Late Pleistocene and Holocene, and that tropical environments were one of a diverse series of ecosystems exploited by H. sapiens in Africa at the dawn of global migrations.
Bookmarks Related papers MentionsView impact
PLOS ONE, 2019
Despite their ubiquity in Holocene African archaeological assemblages, ostrich eggshell (OES) bea... more Despite their ubiquity in Holocene African archaeological assemblages, ostrich eggshell (OES) beads are rarely studied in detail. An exception is in southern Africa, where there is a proposed relationship between OES bead diameter and the arrival of herding ~2000 years before present. In 1987, Leon Jacobson first observed that beads from forager sites in Namibia tended to be smaller than those associated with herder sites. Studies examining bead size around the Western Cape have generally confirmed Jacobson's findings, though the driving forces of the diameter change remain unknown. Since this time, diameter has become an informal way of distinguishing forager and herder assemblages in southern Africa, but no large-scale studies of OES bead variation have been undertaken. Here we present an expanded analysis of Holocene OES bead diameters from southern, and for the first time, eastern Africa. Results reveal distinct patterns in OES bead size over time, reflecting different local dynamics associated with the spread of herding. In southern Africa, OES diameters display low variability and smaller absolute size through time. While larger beads begin to appear <2000 years ago, most beads in our study remained smaller. In contrast, eastern African OES bead diameters are consistently larger over the last 10,000 years and show no appreciable size change with the introduction of herding. Notably, larger beads thought to be associated with herders in southern Africa fall within the range of eastern African beads, indicating a potential connection between these regions in the Late Holocene consistent with genetic findings. Regional differences in bead size are subtle, on the order of millimeters, yet offer a potentially important line of evidence for investigating the spread of herding in sub-Saharan Africa. In order to understand the meaning of these changes, we encourage additional studies of OES bead assemblages and urge researchers to report individual bead diameters, rather than averages by level.
Bookmarks Related papers MentionsView impact
Archaeological and Anthropological Sciences, 2019
Early herders in eastern Africa built elaborate megalithic cemeteries ~ 5000 BP overlooking what ... more Early herders in eastern Africa built elaborate megalithic cemeteries ~ 5000 BP overlooking what is now Lake Turkana in northwestern Kenya. At least six 'pillar sites' were constructed during a time of rapid change: cattle, sheep, and goats were introduced to the basin as the lake was shrinking at the end of the African Humid Period. Cultural changes at this time include new lithic and ceramic technologies and the earliest monumentality in eastern Africa. Isolated human remains previously excavated from pillar sites east of Lake Turkana seemed to indicate that pillar site platforms were ossuaries for secondary burials. Recent bioarchaeological excavations at four pillar sites west of the lake have now yielded ≥49 individuals, most from primary and some from secondary interments, challenging earlier interpretations. Here we describe the mortuary cavities, and burial contexts, and included items such as adornments from Lothagam North, Lothagam West, Manemanya, and Kalokol pillar sites. In doing so, we reassess previous hypotheses regarding pillar site construction, use, and inter-site variability. We also present the first osteological analyses of skeletons buried at these sites. Although the human remains are fragmentary, they are nevertheless informative about the sex, age, and body size of the deceased and give evidence for health and disease processes. Periosteal moulds of long bone midshafts (n = 34 elements) suggest patterns of terrestrial mobility. Pillar site deposits provide important new insights into early herder lifeways in eastern Africa and the impact of the transition to pastoralism on past human populations.
Bookmarks Related papers MentionsView impact
Science, 2019
How food production first entered eastern Africa ~5000 years ago and the extent to which people m... more How food production first entered eastern Africa ~5000 years ago and the extent to which people moved with livestock is unclear. We present genome-wide data from 41 individuals associated with Later Stone Age, Pastoral Neolithic (PN), and Iron Age contexts in what are now Kenya and Tanzania to examine the genetic impacts of the spreads of herding and farming. Our results support a multi-phase model in which admixture between northeastern African-related peoples and eastern African foragers formed multiple pastoralist groups, including a genetically homogeneous PN cluster. Additional admixture with northeastern and western African-related groups occurred by the Iron Age. These findings support several movements of food producers, while rejecting models of minimal admixture with foragers and of genetic differentiation between makers of distinct PN artifacts.
Bookmarks Related papers MentionsView impact
Proceedings of the National Academy of Sciences, 2018
Monumental architecture is a prime indicator of social complexity, because it requires many peopl... more Monumental architecture is a prime indicator of social complexity, because it requires many people to build a conspicuous structure commemorating shared beliefs. Examining monumentality in differ- ent environmental and economic settings can reveal diverse reasons for people to form larger social units and express unity through architectural display. In multiple areas of Africa, monumentality developed as mobile herders created large cemeteries and practiced other forms of commemoration. The motives for such behavior in sparsely populated, unpredictable landscapes may differ from well- studied cases of monumentality in predictable environments with sedentary populations. Here we report excavations and ground- penetrating radar surveys at the earliest and most massive monu- mental site in eastern Africa. Lothagam North Pillar Site was a communal cemetery near Lake Turkana (northwest Kenya) con- structed 5,000 years ago by eastern Africa’s earliest pastoralists. Inside a platform ringed by boulders, a 119.5-m2 mortuary cavity accommo- dated an estimated minimum of 580 individuals. People of diverse ages and both sexes were buried, and ornaments accompanied most individuals. There is no evidence for social stratification. The uncer- tainties of living on a “moving frontier” of early herding—exacer- bated by dramatic environmental shifts—may have spurred people to strengthen social networks that could provide information and assistance. Lothagam North Pillar Site would have served as both an arena for interaction and a tangible reminder of shared identity.
Bookmarks Related papers MentionsView impact
Journal of Anthropological Archaeology, 2018
Today, pastoral systems in eastern Africa are supported by elaborate social networks that minimiz... more Today, pastoral systems in eastern Africa are supported by elaborate social networks that minimize risk and facilitate the movement of people, animals, and resources across unpredictable, semi-arid landscapes. Although similar structures must have existed in the past, investigations into early herders’ social lives remain underdeveloped. The African archaeological record is exceptional in that monumental burial grounds are a hallmark of early pastoral lifeways as they spread from the Sahara through eastern Africa ∼8000–2000 BP. We review archaeological evidence for pastoralist cemeteries in these regions to ask what role(s) burial grounds played in the transmission of mobile food production. To do so, we invoke a ‘moving frontier’ framework in which social and economic strategies fluctuate during the initial spread of food production, then become more rigid after land use and relationships stabilize on a ‘static frontier.’ Ethnographically-documented mortuary practices among recent eastern African pastoralists provide a model for a static frontier, and reveal emic motivations that could not be drawn from archaeological data alone. Although cemeteries are rare in the ethnographic record, archaeological and ethnohistoric practices form a long gradient of mortuary behaviours that fluctuate in response to changing conditions, and help establish and reify social networks among herders facing instability.
Bookmarks Related papers MentionsView impact
Uploads
Papers by Elizabeth Sawchuk