New Archaeological Evidence for an Early Human Presence at Monte Verde, Chile

Abstract

Questions surrounding the chronology, place, and character of the initial human colonization of the Americas are a long-standing focus of debate. Interdisciplinary debate continues over the timing of entry, the rapidity and direction of dispersion, the variety of human responses to diverse habitats, the criteria for evaluating the validity of early sites, and the differences and similarities between colonization in North and South America. Despite recent advances in our understanding of these issues, archaeology still faces challenges in defining interdisciplinary research problems, assessing the reliability of the data, and applying new interpretative models. As the debates and challenges continue, new studies take place and previous research reexamined. Here we discuss recent exploratory excavation at and interdisciplinary data from the Monte Verde area in Chile to further our understanding of the first peopling of the Americas. New evidence of stone artifacts, faunal remains, and burned areas suggests discrete horizons of ephemeral human activity in a sandur plain setting radiocarbon and luminescence dated between at least ~18,500 and 14,500 cal BP. Based on multiple lines of evidence, including sedimentary proxies and artifact analysis, we present the probable anthropogenic origins and wider implications of this evidence. In a non-glacial cold climate environment of the south-central Andes, which is challenging for human occupation and for the preservation of hunter-gatherer sites, these horizons provide insight into an earlier context of late Pleistocene human behavior in northern Patagonia.

Fig 1. Geomorphological context of the Monte Verde site within the wider context of the Llanquihue drift.

During the last glacial period, piedmont glaciers descended from Andean ice fields to the east occupying and sculpting what today are the Llanquihue Lake and Reloncavi fjord basin. The moraines are complex features representing more than one glacial advance in this terminal position. The primary sandur plains drained glacier discharge during successive advances until ~22,000 cal BP. The latest glacier advance ~17,600 cal BP culminated in the inner ridges, near the present-day lake and sea shorelines of the Llanquihue Lake and Reloncavi basin, respectively, draining through the subsidiary sandur plains of the Río Maullin, Río Negro and Río Gomez [31].

Fig 2. Map of the Monte Verde and Chinchihuapi sites showing the different site sectors, block excavation, test pits and cores carried out during the 2013 excavation season.

Fig 3. Excavated archaeological features.

a: in situ burned feature (No. 3) with charcoal, burned bone fragment (top arrow), and ash associated with an embedded, knapped flake of unsourced limestone (bottom arrow) in Unit 56, site MV-I. The thin, light yellowish orange (10YR 8/3) tephra lens has been removed in and around portions of the feature to expose the underlying gray sand. Inset shows a close-up of the flake after the overlying lens was brushed from its upper surface; b: in situ scorched bone fragment (left arrow) and a percussion flake of unsourced limestone (see S7f Fig) directly associated with a burned feature (No. 6, dotted line defines dark ashy areas) in Unit 56, site MV-I.

Fig 4. Sedimentary attributes of SCH-4.

a: Planar cross-stratified sand, note the rippled reactivation surface (arrow, Unit 45-A); b: Parallel/planar cross-stratified sand capped by thin, intermittent small-gravel layers (Unit 55); c: Soft sediment deformation structures; note the small fold in the organic layer beneath gravelly sand (arrow, Unit 17); d: Gravel layer disrupted and submerged under a liquefied sand outburst (Unit 56); e-f: Trough cross-bedded sand with thin gravel lag deposits in the bottom (Units 82 and 57, respectively).

Fig 5. Schematic representation of the stratigraphic cross-sections of the MV-I and MV-II sites divided by the drainage of Chinchihuapi Creek.

Location of the corresponding radiocarbon dates and cultural and non-cultural levels in the MV-I and MV-II sites also are shown. Not shown is the stratigraphic profile for the CH-I and CH-II sites; however, their profiles are comparable to that for the MV-I site. The dates listed under the MV-II site represent the range of radiocarbon assays for the overlying non-cultural strata MV-3 (P), MV-4 (Q) and MV-5 (R) and for the single cultural component of MV-II on the buried surface of stratum MV-7 (S). Since these dates were published previously [13,14,25], their laboratory numbers are not provided here (see Table 1). Radiocarbon dates in site MV-I are in stratigraphic order but at slightly different depths due to the downward sloping strata in site MV-I (see Text B in S1 File).

Fig 6. Various cultural stone tools and manuports from the 2013 ¹⁴C dated archaeological horizons in sites MV-I and CH-1, classified by Collin’s typology of Groups (43).

a: Group 23 manuport of a fractured pinkish quartzite probably derived from a beach of the Pacific Ocean; b. Group 5f pebble flake tool of basalt showing multiple percussion facets; c. Round Smooth possible sling stone of andesite, note the dull matte finish; d. Group 5f pebble flake tool of rhyolite (worked edge at the bottom, arrow shows percussion facet); e. two Group 5f knapped flakes of exotic, unsourced limestone raw material, note the striking platforms and bulb of percussions [arrow]; f. Group 5f pebble flake tool of basalt, note the striking platform and bulb of percussion at top [arrow]; g. Exotic discoid manuport of unknown raw material probably from a beach of the Pacific Ocean; h. Group 5f knapped core of andesite with multiple percussion flake scars; i. Group 5f flake tool of basalt, note the striking platform and bulb of percussion [arrow]; j. flake scatters of basalt produced by knapping; k. Group 5f flaked tool of basalt, note the striking platform [arrow] (see S1 and S2 Tables for more details and S7 Fig for drawings of selected lithics).

Fig 7. Serpentine pebble tool from Unit 17, MV-I, showing bifacially knapped and retouched edge. Serpentine is a raw material available in the coastal cordillera west of Monte Verde.

Fig 8. Basalt wedge showing seven facets on obverse face (one of which is cortex) and three on the reverse face.

Arrows indicate inferred direction of force and point of impact of the blow that detached this piece.

Fig 9. Paijan-like projectile point of rhyolite recovered from a late Pleistocene level at the CH-I site (Unit 6, Level 51 cm; see S6a Fig).

A drill fragment is from the same level (right side).