• Digital Humanities and Cultural Heritage
• Publications close
• Science close

Indigenous societies are known to have occupied the Amazon basin for more than 12,000 years, but the scale of their influence on Amazonian forests remains uncertain. We report the discovery, using LIDAR (light detection and ranging) information from across the basin, of 24 previously undetected pre-Columbian earthworks beneath the forest canopy. Modeled distribution and abundance of large-scale archaeological sites across Amazonia suggest that between 10,272 and 23,648 sites remain to be discovered and that most will be found in the southwest. We also identified 53 domesticated tree species significantly associated with earthwork occurrence probability, likely suggesting past management practices. Closed-canopy forests across Amazonia are likely to contain thousands of undiscovered archaeological sites around which pre-Columbian societies actively modified forests, a discovery that opens opportunities for better understanding the magnitude of ancient human influence on Amazonia and its current state. Indigenous societies have lived in the Amazon for at least 12,000 years. Finding evidence of these societies, however, has been greatly hampered by the density of the forest in Amazonia. Peripato et al. used LIDAR (light detection and ranging) surveys to identify more than 20 previously unidentified developments and then modeled the occurrence of others across the Amazon. The authors predict that between 10,000 and 24,000 ancient earthworks are waiting to be discovered. Sampling of some of the LIDAR transects revealed a consistent set of domesticated tree species associated with the developments, suggesting active forestry practices among these societies. —Sacha Vignieri Amazon-wide LIDAR surveys and predictive models suggest thousands of undocumented archaeological sites across the basin. Archaeological discoveries beneath the canopy Modeling basin-wide distribution of earthworks Relationships with domesticated species Social-ecological implications

The cause, or causes, of the Pleistocene megafaunal extinctions have been difficult to establish, in part because poor spatiotemporal resolution in the fossil record hinders alignment of species disappearances with archeological and environmental data. We obtained 172 new radiocarbon dates on megafauna from Rancho La Brea in California spanning 15.6 to 10.0 thousand calendar years before present (ka). Seven species of extinct megafauna disappeared by 12.9 ka, before the onset of the Younger Dryas. Comparison with high-resolution regional datasets revealed that these disappearances coincided with an ecological state shift that followed aridification and vegetation changes during the Bølling-Allerød (14.69 to 12.89 ka). Time-series modeling implicates large-scale fires as the primary cause of the extirpations, and the catalyst of this state shift may have been mounting human impacts in a drying, warming, and increasingly fire-prone ecosystem.

The horse is central to many Indigenous cultures across the American Southwest and the Great Plains. However, when and how horses were first integrated into Indigenous lifeways remain contentious, with extant models derived largely from colonial records. We conducted an interdisciplinary study of an assemblage of historic archaeological horse remains, integrating genomic, isotopic, radiocarbon, and paleopathological evidence. Archaeological and modern North American horses show strong Iberian genetic affinities, with later influx from British sources, but no Viking proximity. Horses rapidly spread from the south into the northern Rockies and central plains by the first half of the 17th century CE, likely through Indigenous exchange networks. They were deeply integrated into Indigenous societies before the arrival of 18th-century European observers, as reflected in herd management, ceremonial practices, and culture. Horses evolved in North America and dispersed to Eurasia across the Bering Land Bridge. They continued to evolve and were domesticated in Eurasia, but, as far as we know, they became extinct in North America by the late Pleistocene and were then reintroduced by European colonizers. Taylor et al. looked at the genetics of horses across the Old and New Worlds and studied archaeological samples. They found no evidence for direct Pleistocene ancestry of North American horses, but they did find that horses of European descent had been integrated into indigenous cultures across western North America long before the arrival of Europeans in that region. ?SNV Indigenous societies adopted horses of primarily Spanish origin before Europeans arrived in the Great Plains and the American West. Results - Indigenous societies incorporated horses before the Pueblo Revolt - Historic North American horses descend primarily from Spanish genetic sources - Pre–Pueblo Revolt contribution of horses to Indigenous beliefs, trade, and transport networks Discussion

We examined the productivity effects of a generative artificial intelligence (AI) technology, the assistive chatbot ChatGPT, in the context of midlevel professional writing tasks. In a preregistered online experiment, we assigned occupation-specific, incentivized writing tasks to 453 college-educated professionals and randomly exposed half of them to ChatGPT. Our results show that ChatGPT substantially raised productivity: The average time taken decreased by 40% and output quality rose by 18%. Inequality between workers decreased, and concern and excitement about AI temporarily rose. Workers exposed to ChatGPT during the experiment were 2 times as likely to report using it in their real job 2 weeks after the experiment and 1.6 times as likely 2 months after the experiment.

T cells are the major arm of the immune system responsible for controlling and regressing cancers. To identify genes limiting T cell function, we conducted genome-wide CRISPR knockout screens in human chimeric antigen receptor (CAR) T cells. Top hits were MED12 and CCNC , components of the Mediator kinase module. Targeted MED12 deletion enhanced antitumor activity and sustained the effector phenotype in CAR- and T cell receptor–engineered T cells, and inhibition of CDK8/19 kinase activity increased expansion of nonengineered T cells. MED12 -deficient T cells manifested increased core Meditator chromatin occupancy at transcriptionally active enhancers—most notably for STAT and AP-1 transcription factors—and increased IL2RA expression and interleukin-2 sensitivity. These results implicate Mediator in T cell effector programming and identify the kinase module as a target for enhancing potency of antitumor T cell responses.

We present the first ancient DNA data from the Pre-Pottery Neolithic of Mesopotamia (Southeastern Turkey and Northern Iraq), Cyprus, and the Northwestern Zagros, along with the first data from Neolithic Armenia. We show that these and neighboring populations were formed through admixture of pre-Neolithic sources related to Anatolian, Caucasus, and Levantine hunter-gatherers, forming a Neolithic continuum of ancestry mirroring the geography of West Asia. By analyzing Pre-Pottery and Pottery Neolithic populations of Anatolia, we show that the former were derived from admixture between Mesopotamian-related and local Epipaleolithic-related sources, but the latter experienced additional Levantine-related gene flow, thus documenting at least two pulses of migration from the Fertile Crescent heartland to the early farmers of Anatolia. The newly reported dataset is described in detail in an accompanying Research Article, where we also acknowledge the funders who supported dataset generation (12). Analysis of data was supported by the National Institutes of Health (GM100233 and HG012287), the John Templeton Foundation (grant 61220), a private gift from Jean-Francois Clin, the Allen Discovery Center program, a Paul G. Allen Frontiers Group advised program of the Paul G. Allen Family Foundation, and the Howard Hughes Medical Institute (D.R.). National Institutes of Health [GM100233, HG012287]; John Templeton Foundation [61220]; Allen Discovery Center program; Paul G. Allen Frontiers Group advised program of the Paul G. Allen Family Foundation; Howard Hughes Medical Institute