The timing and effect of the earliest human arrivals in North America


The peopling of the Americas marks a major expansion of humans across the planet. However, questions regarding the timing and mechanisms of this dispersal remain, and the previously accepted model (termed ‘Clovis-first’)—suggesting that the first inhabitants of the Americas were linked with the Clovis tradition, a complex marked by distinctive fluted lithic points1—has been effectively refuted. Here we analyse chronometric data from 42 North American and Beringian archaeological sites using a Bayesian age modelling approach, and use the resulting chronological framework to elucidate spatiotemporal patterns of human dispersal. We then integrate these patterns with the available genetic and climatic evidence. The data obtained show that humans were probably present before, during and immediately after the Last Glacial Maximum (about 26.5–19 thousand years ago)2,3 but that more widespread occupation began during a period of abrupt warming, Greenland Interstadial 1 (about 14.7–12.9 thousand years before ad 2000)4. We also identify the near-synchronous commencement of Beringian, Clovis and Western Stemmed cultural traditions, and an overlap of each with the last dates for the appearance of 18 now-extinct faunal genera. Our analysis suggests that the widespread expansion of humans through North America was a key factor in the extinction of large terrestrial mammals.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Map showing the location of the 42 archaeological sites included in this study.
Fig. 2: Start boundaries or age estimates for pre-Clovis sites or components, and a summarized distribution of chronometric data.
Fig. 3: Start boundaries for the Clovis, Western Stemmed and Beringian traditions, and a summarized distribution of the dates for the last appearance of 24 extinct mammal genera in North America.

Data availability

The data that support the findings of this study are available in the Article and its Supplementary Information.

Code availability

Code for OxCal is noted in the Supplementary Information.


  1. 1.

    Meltzer, D. J. The Great Paleolithic War: How Science Forged an Understanding of America’s Ice Age Past (Univ. Chicago Press, 2015).

  2. 2.

    Mix, A. C., Bard, E. & Schneider, R. Environmental processes of the Ice Age: land, oceans, glaciers (EPILOG). Quat. Sci. Rev. 20, 627–657 (2001).

    ADS  Google Scholar 

  3. 3.

    Clark, P. U. et al. The Last Glacial Maximum. Science 325, 710–714 (2009).

    ADS  CAS  PubMed  Google Scholar 

  4. 4.

    Rasmussen, S. O. et al. A stratigraphic framework for abrupt climatic changes during the Last Glacial period based on three synchronized Greenland ice-core records: refining and extending the INTIMATE event stratigraphy. Quat. Sci. Rev. 106, 14–28 (2014).

    ADS  Google Scholar 

  5. 5.

    Waters, M. R. & Stafford, T. W. Jr. Redefining the age of Clovis: implications for the peopling of the Americas. Science 315, 1122–1126 (2007).

    ADS  CAS  PubMed  Google Scholar 

  6. 6.

    Dillehay, T. D. Monte Verde, a Late Pleistocene Settlement in Chile: The Archaeological Context and Interpretation (Smithsonian Institution Press, 1997).

  7. 7.

    Williams, T. J. et al. Evidence of an early projectile point technology in North America at the Gault site, Texas, USA. Sci. Adv. 4, eaar5954 (2018).

    ADS  PubMed  PubMed Central  Google Scholar 

  8. 8.

    Waters, M. R. et al. Pre-Clovis projectile points at the Debra L. Friedkin site, Texas–implications for the Late Pleistocene peopling of the Americas. Sci. Adv. 4, eaat4505 (2018).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  9. 9.

    Haynes, G. The millennium before Clovis. PaleoAmerica 1, 134–162 (2015).

    Google Scholar 

  10. 10.

    Sandweiss, D. H. et al. Quebrada Jaguay: early South American maritime adaptations. Science 281, 1830–1832 (1998).

    ADS  CAS  PubMed  Google Scholar 

  11. 11.

    Goebel, T. & Keene, J. L. in Archaeology in the Great Basin and Southwest: Papers in Honor of Don D. Fowler (eds Parezo, N. J. & Janetski, J. C.) 35–60 (Univ. Utah Press, 2014).

  12. 12.

    Méndez, C., Jackson, D., Seguel, R. & Delaunay, A. N. Early high-quality lithic procurement in the semiarid north of Chile. Curr. Res. Pleistocene 27, 19–21 (2010).

    Google Scholar 

  13. 13.

    Méndez, C. & Jackson, D. Terminal Pleistocene lithic technology and use of space in Central Chile. Chungara (Arica) 47, 53–65 (2015).

    Google Scholar 

  14. 14.

    Jones, K. B., Hodgins, G. W. L. & Sandweiss, D. H. Radiocarbon chronometry of site QJ-280, Quebrada Jaguay, a Terminal Pleistocene to Early Holocene fishing site in southern Peru. J. Island Coast. Archaeol. 14, 82–100 (2017).

    Google Scholar 

  15. 15.

    Davis, L. G. et al. Late Upper Paleolithic occupation at Cooper’s Ferry, Idaho, USA shows Americas settled before ~16,000 years ago. Science 365, 891–897 (2019).

    ADS  CAS  Google Scholar 

  16. 16.

    Braje, T. J., Dillehay, T. D., Erlandson, J. M., Klein, R. G. & Rick, T. C. Finding the first Americans. Science 358, 592–594 (2017).

    ADS  CAS  PubMed  Google Scholar 

  17. 17.

    Potter, B. A. et al. Current evidence allows multiple models for the peopling of the Americas. Sci. Adv. 4, eaat5473 (2018).

    ADS  PubMed  PubMed Central  Google Scholar 

  18. 18.

    Bronk Ramsey, C. Development of the radiocarbon program OxCal. Radiocarbon 43, 355–363 (2001).

    Google Scholar 

  19. 19.

    Bronk Ramsey, C. Bayesian analysis of radiocarbon dates. Radiocarbon 51, 337–360 (2009).

    Google Scholar 

  20. 20.

    Rasmussen, S. O. et al. A new Greenland ice core chronology for the last glacial termination. J. Geophys. Res. 111, D06102 (2006).

    ADS  Google Scholar 

  21. 21.

    Reimer, P. J. et al. IntCal13 and Marine13 radiocarbon age calibration curves 0–50,000 years cal BP. Radiocarbon 55, 1869–1887 (2013).

    CAS  Google Scholar 

  22. 22.

    Adolphi, F. et al. Connecting the Greenland ice-core and U/Th timescales via cosmogenic radionuclides: testing the synchroneity of Dansgaard–Oeschger events. Clim. Past 14, 1755–1781 (2018).

    Google Scholar 

  23. 23.

    Ray, N. & Adams, J. A GIS-based vegetation map of the world at the last glacial maximum (25,000–15,000 BP). Internet Archaeol. 11, (2001).

  24. 24.

    Jackson, S. T. et al. Vegetation and environment in Eastern North America during the Last Glacial Maximum. Quat. Sci. Rev. 19, 489–508 (2000).

    ADS  Google Scholar 

  25. 25.

    Williams, J. W. Variations in tree cover in North America since the Last Glacial Maximum. Global Planet. Change 35, 1–23 (2003).

    ADS  MathSciNet  Google Scholar 

  26. 26.

    Lyle, M. et al. Out of the tropics: the Pacific, Great Basin lakes, and late Pleistocene water cycle in the western United States. Science 337, 1629–1633 (2012).

    ADS  CAS  PubMed  Google Scholar 

  27. 27.

    Goebel, T., Hockett, B., Adams, K. D., Rhode, D. & Graf, K. Climate, environment, and humans in North America’s Great Basin during the Younger Dryas, 12,900–11,600 calendar years ago. Quat. Int. 242, 479–501 (2011).

    Google Scholar 

  28. 28.

    Menking, K. M., Anderson, R. Y., Shafike, N. G., Syed, K. H. & Allen, B. D. Wetter or colder during the Last Glacial Maximum? Revisiting the pluvial lake question in southwestern North America. Quat. Res. 62, 280–288 (2004).

    Google Scholar 

  29. 29.

    Kirby, M. E. et al. A late Wisconsin (32–10k cal a BP) history of pluvials, droughts and vegetation in the Pacific south-west United States (Lake Elsinore, CA). J. Quat. Sci. 33, 238–254 (2018).

    Google Scholar 

  30. 30.

    Ibarra, D. E. et al. Warm and cold wet states in the western United States during the Pliocene–Pleistocene. Geology 46, 355–358 (2018).

    ADS  Google Scholar 

  31. 31.

    Feakins, S. J., Wu, M. S., Ponton, C. & Tierney, J. E. Biomarkers reveal abrupt switches in hydroclimate during the last glacial in southern California. Earth Planet. Sci. Lett. 515, 164–172 (2019).

    ADS  CAS  Google Scholar 

  32. 32.

    Stanford, D. J. & Bradley, B. A. Across Atlantic Ice: The Origin of America’s Clovis Culture (Univ of California Press, 2013).

  33. 33.

    Aubry, T. & Almeida, M. Analyse critique des bases chronostratigraphiques de la structuration du Solutréen. Le Solutréen 40, 37e52 (2013).

    Google Scholar 

  34. 34.

    Eren, M. I., Patten, R. J., O’Brien, M. J. & Meltzer, D. J. Refuting the technological cornerstone of the Ice-Age Atlantic crossing hypothesis. J. Archaeol. Sci. 40, 2934–2941 (2013).

    Google Scholar 

  35. 35.

    Raff, J. A. & Bolnick, D. A. Does mitochondrial haplogroup X indicate ancient trans-Atlantic migration to the Americas? A critical re-evaluation. PaleoAmerica 1, 297–304 (2015).

    Google Scholar 

  36. 36.

    Lisiecki, L. E. & Raymo, M. E. A Pliocene–Pleistocene stack of 57 globally distributed benthic δ18O records. Paleoceanography 20, PA1003 (2005).

    ADS  Google Scholar 

  37. 37.

    Spratt, R. M. & Lisiecki, L. E. A Late Pleistocene sea level stack. Clim. Past 12, 1079–1092 (2016).

    Google Scholar 

  38. 38.

    Pico, T., Mitrovica, J. X., Ferrier, K. L. & Braun, J. Global ice volume during MIS 3 inferred from a sea-level analysis of sedimentary core records in the Yellow River Delta. Quat. Sci. Rev. 152, 72–79 (2016).

    ADS  Google Scholar 

  39. 39.

    Batchelor, C. L. et al. The configuration of Northern Hemisphere ice sheets through the Quaternary. Nat. Commun. 10, 3713 (2019).

    ADS  PubMed  PubMed Central  Google Scholar 

  40. 40.

    Dalton, A. S., Finkelstein, S. A., Barnett, P. J. & Forman, S. L. Constraining the Late Pleistocene history of the Laurentide Ice Sheet by dating the Missinaibi Formation, Hudson Bay Lowlands, Canada. Quat. Sci. Rev. 146, 288–299 (2016).

    ADS  Google Scholar 

  41. 41.

    Pico, T., Mitrovica, J. X. & Mix, A. C. Sea level fingerprinting of the Bering Strait flooding history detects the source of the Younger Dryas climate event. Sci. Adv. 6, eaay2935 (2020).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  42. 42.

    Dyke, A. S. An outline of North American deglaciation with emphasis on central and northern Canada. Develop. Quat. Sci. 2, 373–424 (2004).

    Google Scholar 

  43. 43.

    Lesnek, A. J., Briner, J. P., Lindqvist, C., Baichtal, J. F. & Heaton, T. H. Deglaciation of the Pacific coastal corridor directly preceded the human colonization of the Americas. Sci. Adv. 4, eaar5040 (2018).

    ADS  PubMed  PubMed Central  Google Scholar 

  44. 44.

    Tamm, E. et al. Beringian standstill and spread of Native American founders. PLoS ONE 2, e829 (2007).

    ADS  PubMed  PubMed Central  Google Scholar 

  45. 45.

    Moreno-Mayar, J. V. et al. Early human dispersals within the Americas. Science 362, eaav2621 (2018).

    ADS  PubMed  PubMed Central  Google Scholar 

  46. 46.

    Moreno-Mayar, J. V. et al. Terminal Pleistocene Alaskan genome reveals first founding population of Native Americans. Nature 553, 203–207 (2018).

    ADS  CAS  PubMed  Google Scholar 

  47. 47.

    Ardelean, C. F. et al. Evidence of human occupation in Mexico around the Last Glacial Maximum. Nature (2020).

  48. 48.

    Goodyear, A. C. in Paleoamerican Origins: Beyond Clovis (eds. Bonnichesen, R. et al.) 103–112 (Centre for the Study of the First Americans, 2005).

  49. 49.

    Llamas, B. et al. Ancient mitochondrial DNA provides high-resolution time scale of the peopling of the Americas. Sci. Adv. 2, e1501385 (2016).

    ADS  PubMed  PubMed Central  Google Scholar 

  50. 50.

    Pinotti, T. et al. Y chromosome sequences reveal a short Beringian standstill, rapid expansion, and early population structure of Native American founders. Curr. Biol. 29, 149–157.e3 (2019).

    CAS  PubMed  Google Scholar 

  51. 51.

    Bergström, A. et al. Insights into human genetic variation and population history from 929 diverse genomes. Science 367, eaay5012 (2020).

    PubMed  Google Scholar 

  52. 52.

    Raghavan, M. et al. Genomic evidence for the Pleistocene and recent population history of Native Americans. Science 349, aab3884 (2015).

    PubMed  PubMed Central  Google Scholar 

  53. 53.

    Rasmussen, M. et al. The genome of a Late Pleistocene human from a Clovis burial site in western Montana. Nature 506, 225–229 (2014).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  54. 54.

    Reich, D. et al. Reconstructing Native American population history. Nature 488, 370–374 (2012).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  55. 55.

    Scheib, C. L. et al. Ancient human parallel lineages within North America contributed to a coastal expansion. Science 360, 1024–1027 (2018).

    ADS  CAS  PubMed  Google Scholar 

  56. 56.

    Erlandson, J. M. & Braje, T. J. From Asia to the Americas by boat? Paleogeography, paleoecology, and stemmed points of the northwest Pacific. Quat. Int. 239, 28–37 (2011).

    Google Scholar 

  57. 57.

    Williams, T. J. & Madsen, D. B. The Upper Paleolithic of the Americas. PaleoAmerica 6, 4–22 (2019).

    Google Scholar 

  58. 58.

    Gilbert, M. T. P. et al. DNA from pre-Clovis human coprolites in Oregon, North America. Science 320, 786–789 (2008).

    ADS  CAS  PubMed  Google Scholar 

  59. 59.

    Pedersen, M. W. et al. Postglacial viability and colonization in North America’s ice-free corridor. Nature 537, 45–49 (2016).

    ADS  CAS  Google Scholar 

  60. 60.

    Heintzman, P. D. et al. Bison phylogeography constrains dispersal and viability of the ice free corridor in western Canada. Proc. Natl Acad. Sci. USA 113, 8057–8063 (2016).

    CAS  PubMed  Google Scholar 

  61. 61.

    Darvill, C. M., Menounos, B., Goehring, B. M., Lian, O. B. & Caffee, M. W. Retreat of the western Cordilleran Ice Sheet margin during the last deglaciation. Geophys. Res. Lett. 45, 9710–9720 (2018).

    ADS  Google Scholar 

  62. 62.

    Taylor, M. A., Hendy, I. L. & Pak, D. K. Deglacial ocean warming and marine margin retreat of the Cordilleran Ice Sheet in the North Pacific Ocean. Earth Planet. Sci. Lett. 403, 89–98 (2014).

    ADS  CAS  Google Scholar 

  63. 63.

    Martin, P. S. The discovery of America. Science 179, 969–974 (1973).

    ADS  CAS  PubMed  Google Scholar 

  64. 64.

    Surovell, T. A., Pelton, S. R., Anderson-Sprecher, R. & Myers, A. D. Test of Martin’s overkill hypothesis using radiocarbon dates on extinct megafauna. Proc. Natl Acad. Sci. USA 113, 886–891 (2016).

    ADS  CAS  PubMed  Google Scholar 

  65. 65.

    Robinson, G. S., Pigott Burney, L. & Burney, D. A. Landscape paleoecology and megafaunal extinction in southwestern New York state. Ecol. Monogr. 75, 295–315 (2005).

    Google Scholar 

  66. 66.

    Guthrie, R. D. New carbon dates link climatic change with human colonization and Pleistocene extinctions. Nature 441, 207–209 (2006).

    ADS  CAS  PubMed  Google Scholar 

  67. 67.

    Lorenzen, E. D. et al. Species-specific responses of Late Quaternary megafauna to climate and humans. Nature 479, 359–364 (2011).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  68. 68.

    Prescott, G. W., Williams, D. R., Balmford, A., Green, R. E. & Manica, A. Quantitative global analysis of the role of climate and people in explaining Late Quaternary megafaunal extinctions. Proc. Natl Acad. Sci. USA 109, 4527–4531 (2012).

    ADS  CAS  PubMed  Google Scholar 

  69. 69.

    Cooper, A. et al. Abrupt warming events drove Late Pleistocene Holarctic megafaunal turnover. Science 349, 602–606 (2015).

    ADS  CAS  PubMed  Google Scholar 

  70. 70.

    Araujo, B. B. A., Oliveira-Santos, L. G. R., Lima-Ribeiro, M. S., Diniz-Filho, J. A. F. & Fernandez, F. A. S. Bigger kill than chill: the uneven roles of humans and climate on Late Quaternary megafaunal extinctions. Quat. Int. 431, 216–222 (2017).

    Google Scholar 

  71. 71.

    Firestone, R. B. et al. Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling. Proc. Natl Acad. Sci. USA 104, 16016–16021 (2007).

    ADS  CAS  PubMed  Google Scholar 

  72. 72.

    Broughton, J. M. & Weitzel, E. M. Population reconstructions for humans and megafauna suggest mixed causes for North American Pleistocene extinctions. Nat. Commun. 9, 5441 (2018).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  73. 73.

    Grayson, D. K. & Meltzer, D. J. Revisiting Paleoindian exploitation of extinct North American mammals. J. Archaeol. Sci. 56, 177–193 (2015).

    Google Scholar 

  74. 74.

    Buck, C. E. & Bard, E. A calendar chronology for Pleistocene mammoth and horse extinction in North America based on Bayesian radiocarbon calibration. Quat. Sci. Rev. 26, 2031–2035 (2007).

    ADS  Google Scholar 

  75. 75.

    Slon, V. et al. Neandertal and Denisovan DNA from Pleistocene sediments. Science 356, 605–608 (2017).

    ADS  CAS  Google Scholar 

  76. 76.

    Bueno, L., Politis, G., Prates, L. & Steele, J. A Late Pleistocene/early Holocene archaeological 14C database for Central and South America: palaeoenvironmental contexts and demographic interpretations. Quat. Int. 301, 1–158 (2013).

    Google Scholar 

  77. 77.

    Bond, J. D. Paleodrainage map of Beringia, Yukon Geological Survey, open file 2019-2. (2019).

  78. 78.

    Clark, G. A. in The Settlement of the American Continents (ed. Barton, C. M. et al.) 103–112 (Univ. Arizona Press, 2004).

  79. 79.

    Harris, E. C. Principles of Archaeological Stratigraphy (Elsevier, 2014).

  80. 80.

    Gelfand, A. E. & Smith, A. F. M. Sampling-based approaches to calculating marginal densities. J. Am. Stat. Assoc. 85, 398–409 (1990).

    MathSciNet  MATH  Google Scholar 

  81. 81.

    Gilks, W. R., Richardson, S. & Spiegelhalter, D. Markov Chain Monte Carlo in Practice (Chapman and Hall/CRC, 1995).

  82. 82.

    Bronk Ramsey, C. Radiocarbon calibration and analysis of stratigraphy: the OxCal program. Radiocarbon 37, 425–430 (1995).

    CAS  Google Scholar 

  83. 83.

    Bronk Ramsey, C. Dealing with outliers and offsets in radiocarbon dating. Radiocarbon 51, 1023–1045 (2009).

    Google Scholar 

  84. 84.

    Rosenblatt, M. Remarks on some nonparametric estimates of a density function. Ann. Math. Stat. 27, 832–837 (1956).

    MathSciNet  MATH  Google Scholar 

  85. 85.

    Parzen, E. On estimation of a probability density function and mode. Ann. Math. Stat. 33, 1065–1076 (1962).

    MathSciNet  MATH  Google Scholar 

  86. 86.

    Bronk Ramsey, C. Methods for summarizing radiocarbon datasets. Radiocarbon 59, 1809–1833 (2017).

    Google Scholar 

  87. 87.

    Silverman, B. W. Density Estimation for Statistics and Data Analysis (Chapman & Hall, 1986).

  88. 88.

    Bronk Ramsey, C. OxCal 4.3 Manual. (2020).

  89. 89.

    Stafford, T. W. Jr, Duhamel, R. C., Haynes, C. V. Jr & Brendel, K. Isolation of proline and hydroxyproline from fossil bone. Life Sci. 31, 931–938 (1982).

    CAS  PubMed  Google Scholar 

  90. 90.

    Stafford, T. W., Brendel, K. & Duhamel, R. C. Radiocarbon, 13C and 15N analysis of fossil bone: removal of humates with XAD-2 resin. Geochim. Cosmochim. Acta 52, 2257–2267 (1988).

    ADS  CAS  Google Scholar 

  91. 91.

    Deviese, T., Comeskey, D., McCullagh, J., Bronk Ramsey, C. & Higham, T. New protocol for compound-specific radiocarbon analysis of archaeological bones. Rapid Commun. Mass Spectrom. 32, 373–379 (2018).

    ADS  CAS  PubMed  Google Scholar 

  92. 92.

    Devièse, T. et al. Increasing accuracy for the radiocarbon dating of sites occupied by the first Americans. Quat. Sci. Res. 198, 171–180 (2018).

    ADS  Google Scholar 

  93. 93.

    Becerra-Valdivia, L. et al. Reassessing the chronology of the archaeological site of Anzick. Proc. Natl Acad. Sci. USA 115, 7000–7003 (2018).

    CAS  PubMed  Google Scholar 

  94. 94.

    Waters, M. R., Stafford, T. W. Jr, Kooyman, B. & Hills, L. V. Late Pleistocene horse and camel hunting at the southern margin of the ice-free corridor: reassessing the age of Wally’s Beach, Canada. Proc. Natl Acad. Sci. USA 112, 4263–4267 (2015).

    ADS  CAS  PubMed  Google Scholar 

  95. 95.

    Bronk Ramsey, C., Housley, R. A., Lane, C. S., Smith, V. C. & Pollard, A. M. The RESET tephra database and associated analytical tools. Quat. Sci. Rev. 118, 33–47 (2015).

    ADS  Google Scholar 

  96. 96.

    Derek Hamilton, W. & Krus, A. M. The myths and realities of Bayesian chronological modeling revealed. Am. Antiq. 83, 187–203 (2018).

    Google Scholar 

Download references


Without implying their agreement with the content of this article, we thank E. Jacob, G. Wali, J. Swift, C. Bronk Ramsey, J. Lee-Thorp, K. Graf and K. Douka for their feedback on versions of the manuscript. We are grateful to the staff of the Oxford Radiocarbon Accelerator Unit, University of Oxford. Funding was provided by the Clarendon Fund Scholarship, University of Oxford.

Author information




L.B.-V. compiled archaeological and chronometric data and built Bayesian age models. L.B.-V. and T.H. analysed modelled output and wrote the manuscript.

Corresponding author

Correspondence to Lorena Becerra-Valdivia.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature thanks Loren G. Davis, Christopher L. Hill and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Fig. 1 Bayesian age model and start boundary for the Beringian tradition (14,955–13,895 cal. bp).

Right, estimate rounded to 50. Outlier analysis output (O) is noted as ‘posterior probability/prior probability’. δ18O data are according to the Greenland ice-core timescale (GICC05)20.

Extended Data Fig. 2 Bayesian age model and start boundary for the Western Stemmed tradition (14,860–13,065 cal. bp).

Outlier analysis output (O) is noted as ‘posterior probability/prior probability’. δ18O data are according to the Greenland ice-core timescale (GICC05)20.

Extended Data Fig. 3 Bayesian age model and start boundary for Clovis tradition (14,210–13,495 cal. bp).

Outlier analysis output (O) is noted as ‘posterior probability/prior probability’. δ18O data are according to the Greenland ice core timescale (GICC05)20.

Extended Data Fig. 4 Spatio-temporal slices of chronometric data belonging to the cultural components analysed, with a spatial KDE analysis.

af, Coloured circles (following colour scheme in Fig. 1) denote chronometric data (n = 387 dates) and white outlines reflect the spatial KDE analysis. Chronometric data were summarized using a KDE_Model analysis (Methods). For each date, differences in circle size reflect increasing or decreasing probabilities at a 95.4% confidence interval. The spatial KDE analysis shows a marked increase in the frequency and distribution of the data immediately, before and during GI-1.

Supplementary information

Supplementary Information

This Supplementary Information file contains a description of the archaeological traditions discussed, information on the archaeological sites included in the analyses and notes on their Bayesian age modelling (including OxCal code), data tabulations tables (S1 and S2), a brief discussion on excluded archaeological sites, and the results of sensitivity testing and ‘Difference’ queries. Readers are guided by a hyperlinked Table of Contents, at the beginning of the document.

Reporting Summary

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Becerra-Valdivia, L., Higham, T. The timing and effect of the earliest human arrivals in North America. Nature (2020).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.