An updated radiocarbon dataset of late Pleistocene to Holocene archaeological sites in the Cubilán area, southern highland Ecuador

Highlights

• Radiocarbon data from six archaeological sites indicate repeated visits to a region of about 3,000 masl in southern Ecuador from the late Pleistocene into the late Holocene.

• The focus of activities over the course of nearly 10,000 years in the Cubilán area was on the procurement of lithic materials and the manufacture of stone tools.

• Significant tests of large radiocarbon datasets from sites in a single region allow the identification of the timing and intensity of regional occupations not otherwise determinable.

Abstract

Thirty-two radiocarbon dates obtained from four archaeological sites in the southern Andean Range of Ecuador are presented in order to contribute toward filling existing chronological and interpretive gaps regarding human occupations in highland South America, mainly during the late Pleistocene to early Holocene transition. These radiocarbon dates, together with nine other dates previously obtained for the studied area, were submitted to significance tests analyses to assess which of them are statistically similar at the intra- and inter-site scales. Pooled mean ages and respective clusters of dates were combined with isolated dates of studied sites, and with artifactual data aiming at producing some initial interpretations regarding micro-regional human dynamics for southern highland Ecuador through time. In the studied area of ~55 km² diverse anthropogenic scenarios directly linked with proposed chronological stages are briefly described. These activities suggest that local and micro-regional human interaction dynamics were consistent, continuous, and complex through time from 12,000 cal. BP onward.

Introduction

Evidence of early human presence has been consistently recovered in all the main physiographic regions of Ecuador (Fig. 1) such as the coast, the tropical mid-altitude rainforests to the east and west of the Andes, the Andes Mountain Range itself and Amazonia (Constantine, 2013a; Stothert and Sánchez, 2011). However, little is known about the southern Ecuadorian Andes regarding micro–regional processes of human interaction during the late Pleistocene through the mid and late Holocene there. This is particularly due to the limited registry of early localities throughout Ecuador, in addition to the lack of robust radiocarbon datasets for the different epochs comprising what has been labeled as the Preceramic period.

For the Pleistocene-Holocene interface, there are clear indications of human activities for the Santa Elena peninsula in coastal Ecuador, within the same area where a Las Vegas complex has been identified (Fig. 1A). These contexts, labeled as “Pre–Las Vegas” in site 80 (Stothert and Sánchez, 2011), have been posited with three radiocarbon dates by around 13,800 to 10,800 cal. BP. Another Pleistocene site previously studied by Temme (2005), and included next in our chronological analysis, falls within the Cubilán area on southern highland Ecuador (Fig. 1B): Cubilán 27 (or Cu–27). This site, reported together with 22 other sites or localities of presumably preceramic ascription, has been interpreted as a lithic workshop after intensive excavations and detailed lithic analyses. Currently, Cu–27 is the second oldest archaeological site so far registered for Ecuador, which dates just after the “Pre–Las Vegas” contexts previously mentioned. Chronological data for Cu–27 consist of two radiocarbon dates that range between ~12,550 and 11,770 cal. BP. Other Pleistocene-Holocene transitional sites are San José in the northern highland range (13 obsidian hydration dates: ~12,000 to 10,000 BP; Mayer-Oakes, 1986) and Montequinto in the western slope of the mountain range (one radiocarbon date: ~11,860 cal. BP; Dominguez et al., 2003 in Stothert and Sánchez, 2011).

Additional sites that fall between early to mid-Holocene age are Las Vegas sites 38B, 78, 80, and 201 in the Santa Elena peninsula (12 radiocarbon dates: ~11,620 to 9540 cal. BP; Stothert and Sánchez, 2011), El Inga in the northern highland range (12 obsidian hydration dates and five radiocarbon dates: ~10,130 cal. BP and later; Bell, 2000; Mayer-Oakes, 1986), Guaguacanoayacu in the eastern slope of the mountain range (two radiocarbon dates: ~11,280 to 9900 cal. BP; Stothert and Sánchez, 2011), and Chobshi in the southern highland range (two radiocarbon dates: ~9630 to 8400 cal. BP; Lynch and Pollock, 1981). Another archaeological site subjected to chronological analysis in further sections of this paper is Cubilán 26 (or Cu-26), which is located in the same area as Cu-27 and is chronologically supported by two radiocarbon dates ranging from ~10,420 to 10,130 cal. BP (Temme, 2005). There are more archaeological sites in Ecuador with clear indications of human activities dated to around the mid Holocene: Las Vegas sites 38A, 66, 67, 80, 202, 203, 213 in coastal Ecuador (14 radiocarbon dates: ~9410 to 6700 cal. BP; Stothert and Sánchez, 2011), Gran Cacao in the Río Guayas watershed of the western lowlands (one radiocarbon date: ~9400 cal. BP; Stothert and Sánchez, 2011), Los Naranjos on the western slope of the northern highlands (four radiocarbon dates: ~7350 to 6970 cal. BP; Constantine, 2013a), and Las Mercedes just in the same area of Los Naranjos (four radiocarbon dates: ~6900 to 6600 cal. BP; Constantine, 2013a).

From the above, it can be summed that there are 12 archaeological sites that fall within the Pleistocene and early Holocene transitional period, i.e., between ~13,800 and 9630 cal. BP. Of these archaeological sites, only site 80 of the Early Las Vegas context is supported by a strong radiocarbon dataset. Chronological histories of other sites such as El Inga and San José are supported by five radiocarbon dates and 25 obsidian hydration dates. Thus far, the chronology of many early sites (site 80 “Pre–Las Vegas”, site 38B, site 78, site 201 of Las Vegas complex, and Cu–26, Cu–27, Montequinto, Guaguacanoayacu, and Chobshi) rely on one to three radiocarbon dates each. In the same way, from 10 archaeological sites that are placed in the mid Holocene, only site 80 (“Late Las Vegas” contexts) has been established with nine radiocarbon dates, while Los Naranjos and Las Mercedes sites are supported by four radiocarbon dates each. Other “Late Las Vegas” sites such as sites 38A, 66, 67, 202, and 203, as well as Gran Cacao, each rely on only one radiocarbon date (Stothert and Sánchez, 2011).

It should be noted that just nine of the 32 sites or localities that comprise the Pre– and Las Vegas complexes in coastal Ecuador have been dated, as well as two of the 26 presumably preceramic localities registered at the Cubilán area and peripheral territories (e.g., Vinoyacu area, Fig. 1B). Placing together these 11 sites with another eight individual preceramic sites mentioned above, there are only 19 (28.8%) dated sites from a total of 66 that have been ascribed to the Preceramic period of Ecuador which is typically bracketed between ~13,000 and 5900/6000 BP (Stothert and Sánchez, 2011). Therefore, if research problems for the Pleistocene-Holocene transitional period are aimed at understanding micro– and macro–regional dynamics of human dispersion, or other inter–regional processes such as human adaptation to local environments and socio–cultural evolution through time (Rademaker et al., 2014), previously described chronological scenarios are not adequate enough. Additionally, chronological hygiene problems have been noted in sites like Chobshi, El Inga, and San José, such as the lack of correspondence between dates and recovered lithic types and the lack of association between radiocarbon or obsidian hydration samples and registered stratigraphic units or artifact typology (see Constantine, 2013a; Stothert and Sánchez, 2011).

In order to add new empirical data for filling the mentioned chronological and interpretive gaps, this paper compile and assesses radiocarbon samples for the Cubilán area that comprises 32 Accelerator Mass Spectrometry (AMS) dates distributed within various archaeological contexts of four sites (Cubilán Site 2 or Cu–S2, Cubilán Site 3 or Cu–S3, Cubilán Site 4 or Cu–S4, and Alero Loma Blanca or ALB) studied by the Instituto Nacional de Patrimonio Cultural of Ecuador (INPC) (Fig. 1B). Nine additional dates included in this analysis were obtained previously by Constantine (2013b) for the sites Cu–S2 and Cu–S3, and by Temme (2005) for sites Cu–26 and Cu–27. In sum, this paper has been sketched as a case study intended to demonstrate that a good collection of radiocarbon dates from multiple early sites relatively close to each other can improve the characterization of the occupational history in this and other regions of highland South America. In this sense, new chronological data here discussed reveal potentially continuous processes of human micro–regional dynamics since the late Pleistocene through the mid to late Holocene, in a relatively reduced area of ~55 km² in which the Cubilán and ALB areas are located.