Evidence of human occupation in Mexico around the Last Glacial Maximum


The initial colonization of the Americas remains a highly debated topic1, and the exact timing of the first arrivals is unknown. The earliest archaeological record of Mexico—which holds a key geographical position in the Americas—is poorly known and understudied. Historically, the region has remained on the periphery of research focused on the first American populations2. However, recent investigations provide reliable evidence of a human presence in the northwest region of Mexico3,4, the Chiapas Highlands5, Central Mexico6 and the Caribbean coast7,8,9 during the Late Pleistocene and Early Holocene epochs. Here we present results of recent excavations at Chiquihuite Cave—a high-altitude site in central-northern Mexico—that corroborate previous findings in the Americas10,11,12,13,14,15,16,17of cultural evidence that dates to the Last Glacial Maximum (26,500–19,000 years ago)18, and which push back dates for human dispersal to the region possibly as early as 33,000–31,000 years ago. The site yielded about 1,900 stone artefacts within a 3-m-deep stratified sequence, revealing a previously unknown lithic industry that underwent only minor changes over millennia. More than 50 radiocarbon and luminescence dates provide chronological control, and genetic, palaeoenvironmental and chemical data document the changing environments in which the occupants lived. Our results provide new evidence for the antiquity of humans in the Americas, illustrate the cultural diversity of the earliest dispersal groups (which predate those of the Clovis culture) and open new directions of research.

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Fig. 1: Setting of Chiquihuite Cave, and the X-12 excavation.
Fig. 2: Bayesian age model of Chiquihuite Cave.
Fig. 3: Examples of lithic artefacts from Chiquihuite Cave.

Data availability

The data that support the findings of this study are available in the Article and its Supplementary Information. Raw data and sequence alignments are available from the European Nucleotide Archive under accession number PRJEB37914. The exact coordinates of Chiquihuite Cave are available from C.F.A. on reasonable request. C.F.A. can also be contacted at cip_ardelean@hotmail.com.

Code availability

Code for R and OxCal is noted within the Supplementary Information. Code for environmental DNA data analysis can be found at https://github.com/miwipe/ngsLCA.


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The field explorations and part of the laboratory studies were made possible by the special sponsorship from the Government of the State of Zacatecas, through the Consejo Zacatecano de Ciencia, Tecnología e Innovación (COZCyT); we thank its consecutive directors, G. A. Mercado-Sánchez and A. Enciso-Muñoz, and the Governor of Zacatecas, A. Tello-Cristerna. Seed money for cave exploration came from the Center for American Paleolithic Research (CAPR); we thank S. Holen, K. Holen and the members of the board. Fieldwork, laboratory analyses and publication expenses were partially covered by CONACYT grant CB-2016-286130. The Concepción del Oro municipality, and A. Maldonado-Falcón, offered administrative and occasional financial assistance. Radiocarbon work at Oxford was supported by the NERC Radiocarbon Facility (NRCF), Merton College, Santander and the Clarendon Fund. We thank all colleagues at the ORAU. D. Peat contributed greatly to laboratory preparation of OSL samples. A. Ocaña and I. Alarcón participated in the identification of animal bones. The environmental DNA work was supported by the Lundbeck Foundation, the Novo Nordic Foundation, the Wellcome Trust Foundation, the Carlsberg Foundation and the Danish National Research Foundation. We thank INAH’s Archaeology Council for authorization and legal permits; the inhabitants of Guadalupe Garzarón for accepting this project in their territory and participating in the caravans; and J. Martínez-Ledezma for his constant support as an on-site administrator and liaison with the community.

Author information




C.F.A. designed the project, directed excavations, analysed lithics, photographed artefacts and put together the research team. L.B.-V. and T.H. performed sampling, AMS radiocarbon dating and Bayesian modelling analysis. C.S.-R. and M.R.-C. performed AMS radiocarbon dating. M.W.P., M.S. and E.W. designed and conducted the DNA and bioinformatic analyses. J.-L.S. undertook the OSL dating. C.G.O. performed geological studies. J.I.M.-Q. participated in the discovery of the site, mapping, artefact plotting and GIS analyses. J.A.-C. conducted the zooarchaeological analysis. L.B.-P. and A.O.-B. conducted chemical residues analysis. J.B.-V. performed X-ray fluorescence. Y.Z.E.O.-D. and I.I.R.-C. conducted thin-section petrography and micromorphology analyses. J.G.W. performed the phytolith analysis. V.B.d.M., P.E.D.O. and I.R.-G. studied pollen samples. Z.N.-G. performed flotation and malacology analyses. D.A.G. performed photogrammetry. Z.N.-G., J.J.D.L.R.-D., V.H.-A., M.B.M.-F., L.M.M.-R., and A.L.-J. excavated. C.F.A., L.B.-V., M.W.P., J.I.M.-Q., J.J.D.L.R.-D. and D.A.G. created figures. C.F.A. wrote the paper with co-authors contributing to the draft.

Corresponding authors

Correspondence to Ciprian F. Ardelean or Eske Willerslev.

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Extended data figures and tables

Extended Data Fig. 1 Additional information on the site and excavation.

a, Digital elevation model (DEM) map of Mexico with the study area (rectangle) in relationship to relevant modern and prehistoric localities. b, The study region (Concepción del Oro endorheic basin), with Chiquihuite Cave (green dot) on the Astillero Mountains. DEM mosaic generated from ortophotographs and elevation data from National Institute of Statistics and Geography (INEGI) of Mexico. c, Chiquihuite Peak, seen from the south; the arrow indicates the entrance of the cave. d, The main chamber, looking west towards the double-eyed entrance. e, Contact between the limestone lintel of the ancient entrance (25 m west of X-12), and the debris that sealed it, probably at the end of the Pleistocene epoch. f, The south profile of the central–eastern squares, as in Fig. 1b. g, Western profiles of the central sector, showing the exposed interface 1210 tilted in the centre of the photograph. h, East–west cross-section of the northern sector of the main chamber of the cave, along the southern profile of the dig. i, X-12 cross-section, showing the inclination of the cave floor and the stepped approach. The DEMs in a, b were created with ArcMap/ArcScene (by ESRI) using open-access topographical data provided by INEGI.

Extended Data Fig. 2 Three-dimensional photogrammetric model of excavation X-12 and the location of samples extracted and analysed for ancient environmental DNA.

a, North-facing profile. b, East-facing profile. Triangles indicate the respective locations of environmental DNA samples extracted in 2019, corresponding to different stratigraphic units (‘UE’, as shown in the key). The circled samples are the initial ones, from the 2016–2017 excavation. c, Complete 3D photogrammetric view of the excavation towards the southern profile. The reddish-brown layers visible along the entire southern profile represent the stratigraphic component C (SC-C), starting downwards with stratum 1212, the terminal LGM chronostratigraphic marker that defines the separation between SC-B and SC-C (Fig. 1b, Extended Data Fig. 7).

Extended Data Fig. 3 Finds plotted onto the excavation grid.

a, Horizontal (x and y axes) spatial distribution of lithic artefacts, radiocarbon and OSL samples on the excavation grid. b, Side view (from the south) of the vertical distribution (x and z axes) of finds and samples. Illustrated dating samples: (1) LEMA-635.1.1 and LEMA-635.1.2; (2) OxA-36608 and LEMA-978.1.1; (3) OxA-36610; (4) LEMA-574.1.1; (5) LEMA-640.1.1; (6) OxA-36496; (7) OxA-36613; (8) X-7227; (9) OxA-36614; (10) LEMA-636.1.1 and LEMA-636.1.2; (11) LEMA-576.1.1; (12) LEMA-577.1.1; (13) X-7228; (14) X-7231 and X-7232; (15) X-7229; (16) OxA-36530; (17) OxA-36633; (18) OxA-36609; (19) OxA-36612; (20) OxA-36360; (21) BETA-345055; (22) X-4135; (23) OxA-34965; (24) ICA-16OS/0510; (25) PRI-5414; (26) OxA-36616; (27) OxA-36620; (28) OxA-36618; (29) OxA-36615; (30) OxA-36617; (31) OxA-36621; (32) OxA-36619; (33) OxA-36753; (34) OxA-36611; (35) X-7233; (36) LEMA-573.1.1; (37) OxA-36359; (38) LEMA-892.1.2; (39) OxA-36622; (40) OxA-36623; (41) OxA-36634; (42) LEMA-893.1.1; (43) LEMA-977.1.1; (44) OxA-36624; and (45) OxA-36625.

Extended Data Fig. 4 Taxonomic profiles of animals (Amniota) and plants (Viridiplantae) identified by ancient environmental DNA.

a, b, Animals presented as the proportion of reads found of each taxa and plotted as a bar plot (b) and stratigraphic plot (a). c, d, All plants are presented as the proportion of reads found of each taxa and plotted as a bar plot (c) and stratigraphic plot (d). *Taxa also found by pollen, phytoliths or faunal remains.

Extended Data Fig. 5 Additional Chiquihuite lithic artefacts.

ac, Cores. d, e, Bifacial preforms on ovoid nodules. fn, Flakes. ot, Blades. ux, Microliths. y, w, Burins. z, a′, Scrapers. b′l′, Points and point-like shapes. m′p′, Geometric items made by fracturing calcite laminae. Artefacts i, n, o, b′, c′, f′, and k′ are from SC-C; all others are from SC-B. Scale bars, 1 cm.

Extended Data Fig. 6 Additional examples of lithics.

a, Core. b, Flake with isolated platform. c, Flake with lipped platform. di, Blades and microlith blade segments. j, Circular scraper on trimmed flake. k, Possible preform. l, Point on plaquette. m, Bifacial point preform. n, o, sa′, d′g′, Transversal points (obtained by slightly modifying transversal flake blanks). pr, b′, c′, Other points. h′, A geometric, point-like shape on calcite sheet. Most artefacts were discovered in SC-B. Specimens xz, b′, g′, h′ are from SC-C. Scale bars, 1 cm.

Extended Data Fig. 7 Stratigraphic correlations across different profiles in X-12.

a, b, Excavation grid diagram (a) and maximum-depth diagram (b) showing the position of the profiles depicted below. For correlation reasons, all profiles show the upper contact of stratum 1210 with 1212 marked with a white contour. The position of OSL samples is indicated (labels beginning with X-). c, South profile, squares K2, K3, L2 and L3. d, South profile, square H2. e, South profile, square G2. f, South profile, square F2. g, South profile, squares M3, M4, N3 and N4. h, West profile, square J4. i, West profile, squares I5 and I6. j, Eastern profile, squares M4, M5 and M6 (profile removed during the 2016–2017 winter excavations). k, Eastern profile, squares N4, N5 and N6 (new eastern profile after the excavation of the one shown in j).

Extended Data Table 1 Chronometric data ordered by strata and depth

Supplementary information

Supplementary Information 1

This file contains the concentration of data from all the different scientific approaches included in the paper. Each proxy-related section is numbered consecutively, from 1 to 10, such as: 1.1. Geology; 1.2. Radiocarbon dating and Bayesian modelling. 1.3. Lithic artefact metrics. 1.4. Chemical residues. 1.5. Faunal remains. 1.6. Phytoliths and pollen. 1.7. Thin-section and micromorphology. 1.8. Commercial radiocarbon dating methods. 1.9. Optically stimulated luminescence (OSL) dating. 1.10. Environmental DNA. Each section number is referred as such in the manuscript.

Reporting Summary

Supplementary Information 2

This file contains plots used in the assessment of ancient DNA authentication for the animal taxa found. The first column contains the read length distribution (in Bp) of the reads aligning to the reference (see supplementary metadata file), the second columns plots the number of mismatches (edit distance) of each read to the same reference. In the third column, the fraction of C-T transitions due to DNA damage, as calculated by mapDamage2.0, is plotted. Each new row contains a new species from a specific layer.

Supplementary Information 3

This file contains plots used in the assessment of ancient DNA authentication for the plant taxa found. The first column contains the read length distribution (in Bp) of the reads aligning to the reference (see supplementary metadata file), the second columns plots the number of mismatches (edit distance) of each read to the same reference. In the third column, the fraction of C-T transitions due to DNA damage, as calculated by mapDamage2.0, is plotted. Each new row contains a new species from a specific layer.

Supplementary Information 4

A link to the 3D digital photogrammetric model of excavation X-12. This is an on-line dynamic model that shows the tridimensional photographic modelling of the excavation, same as in Fig. 1c and Extended Data Fig. 2. It includes the display of the entire spectrum of eDNA samples extracted in 2019 for aDNA reassessment, as well as the northern wall of the cave. The viewer can rotate the model around the x,y,z axis.

Supplementary Data

The eDNA metadata file contains information relating to layer in excavation, excavation coordinate, total sequences sequenced, reads after quality control, sequencing batch, extraction batch, number of replicated samples and total counts of total taxonomically classified reads and total classified reads at the different kingdoms; Bacteria, Viridiplantae, and Amniota. Including reads checked for DNA damage at different mapping qualities (MQ) and the proportion of damage found.

Supplementary Video 1

: A dynamic tridimensional view of the artefact-and-sample plot depicted in Extended Data Fig. 3. This video allows the viewer to appreciate the 3D relationship between the items without the need to run the model in an ArcScene (by ESRI) software. Motion starts at 00:08.

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Ardelean, C.F., Becerra-Valdivia, L., Pedersen, M.W. et al. Evidence of human occupation in Mexico around the Last Glacial Maximum. Nature 584, 87–92 (2020). https://doi.org/10.1038/s41586-020-2509-0

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