Human biogeography

South Africa’s northern Namaqualand coastal desert is the southern extension of the Namib. Today, this region is semi-desert with patchy subsistence resources and scarce, unpredictable rainfall. Yet this ancient desert landscape possesses residues of human activity stretching back into the Middle Pleistocene, evidenced by heavily weathered surface finds, including handaxes and Victoria West cores. Such old finds in so harsh an environment raise important questions: how do human movements into this area relate to local palaeoenvironmental changes, and how has this relationship changed through time? While no dated Middle Pleistocene sites presently exist to reconstruct the earliest hominin dispersals, several late Pleistocene sites now have chronostratigraphic sequences that can be brought to bear on these questions. This article presents chronological and subsistence-settlement data for one such site, Spitzkloof A Rockshelter in northern Namaqualand’s rugged Richtersveld. Humans are shown to have visited the site very sporadically between ∼50,000 and 17,000 cal BP. Unlike most of the subcontinent, the most intensive occupations occur during early Marine Isotope Stage 2, when multiple proxies suggest enhanced humidity associated with intensified winter rainfall. We examine these data using the region’s better-developed Holocene archaeological record to create predictions about the earliest coastal desert dwellers.

Here we present an invited volume in Quaternary International integrated by a series of papers that deal with the human-environment interaction during the initial peopling phase from a continental perspective from Mexico to Patagonia, including the Pacific coast of South America, the Andean highlands, the tropical lowlands and the wide grasslands of the South of the continent. Also the evidences studied and the methodological and theoretical approaches were diverse. This volume is the result of the session chaired for Miguel Delgado and Francisco Aceituno entitled “Multidisciplinary studies on the human-environment interaction during the initial phase of the American peopling” held during the VI International Symposium Early Man in America: Models and Contributions from Tropical Territories” presented in Pereira, Colombia in November (19-24) 2012. The main aims of the session were to offer a place to present recent results favoring multidisciplinary approaches on the interaction between humans, the environment (climate and landscape) and other animal and vegetal species during the Pleistocene/Holocene transition and to discuss new theoretical and methodological strategies to address such interaction from the archaeological record in relation with other evidences.

The Andes mountain range is one key physiographic feature of South America with the potential to have acted as a barrier and corridor for human societies. The goal of this paper is to assess from where and how were the highlands utilized during the last 2000 years, which is a key period witnessing the development of productive economies and changes in the organization of mobility. We develop a regional case study focused on the highland wetland Laguna del Diamante (3300 masl), which is a highly productive ecosystem only accessible during summer. This case is based on a multidisciplinary approach combining: a) geochemical characterization of obsidian sources located in the highlands and artifacts; b) isotopic approach to ranges of paleomobility of individuals by means of 87 Sr/ 86 Sr; and c) stylistic study of ceramic assemblages. The two main obsidian types from the highlands have restricted and decaying spatial distribution, suggesting that these archaeological distributions track part of human circuits of mobility instead of indirect transport acquisition. Their archaeological distribution is heavily skewed towards the western Andean slope. We present strontium isotope values for four teeth and bone samples from two individuals recovered in the area, which are interpreted in reference to a preliminary baseline of biologically available strontium. We infer that these individuals had ranges of paleomobility systematically connecting the western slope with the highlands. The analysis of the ceramic assemblages shows that most of the diagnostic sherds can be assigned to styles that have distributional cores in the Central Valley of Chile up until the time of Inca presence, while only a minimum portion of the sample can be assigned to distributional cores on the eastern slope. By integrating the patterns in the transport of obsidian and ceramic artifacts and the paleomobility of individuals, we find support for the existence of dominant access to the highlands from the western Andean slope. A GIS-based analysis of the seasonality of precipitation shows that the western slope presents more pronounced and drier summer months, providing a context that contributes to explain these patterns. These results contradict previous interpretations suggesting that the archaeological record from the highlands is more directly tied to human groups inhabiting the eastern lowlands during most of the year. Beyond the geographic debate, this issue has an impact on the subsistence organization of the incoming groups, on the socioeconomic role of the highlands, and on the demographic contexts leading to trajectories of economic intensification in both Andean slopes. This research contributes to build a framework for comparative research on human use of highland environments.

Archaeological radiocarbon databases are being increasingly used as a proxy of past demographic trends. In this paper we compile and analyze an extensive database of paleoecological information and 14C dates from archaeological sites in northwestern Patagonia (Argentina, South America). On this basis, we assess the regional distribution of human populations since the late Pleistocene, and their relation with the evolution of Patagonian climate and landscapes. We explore the spatial and temporal distribution of evidence and discuss sampling biases affecting the record in different ecological contexts. The analysis is set in the frame of three main ecological regions that have implications for human subsistence: Andean forest, grass steppe, and shrub steppe. The intensity of the archaeological signal differs among these
regions through time, being stronger and more homogeneous in the grass steppe. In the Andean forest and the shrub steppe the signal is weaker and even absent during short periods of the middle Holocene. We suggest likely sampling biases contributing to these tendencies, since these three regions present variable research cover and intensity. On the other hand, we also suggest that these differences may reflect variations in the intensity of human occupation, in favor of more attractive environments for hunting (i.e., areas where guanaco are generally more abundant). This macro-regional synthesis of the paleoecology and archaeology of northwestern Patagonia provides a platform for developing future oriented research.

We have carried out long-term comparative in a wide latitudinal range of the Andes (29 e37 south), encompassing selected areas that differ in ecology and biogeography. This latitudinal span shows diversity in subsistence modes across time and space, ranging from Andean agro-pastoralists in the north to Patagonian hunter-gatherers in the south. As part of this research, a program of geochemical and archaeological characterization of obsidian sources and distributions is being developed, attempting to assess connections between different biogeographical contexts. This work has allowed recognizing five Andean sources with different geological and topographical properties. Stemming from this macro-regional endeavor, in this paper we present a comparative analysis of the human use of two sources that, based on the intensity of human use on a macro-regional scale, can be interpreted as 'minor' sources. This study is framed on GIS least-cost models for human circulation across rugged landscapes allowing access to the sources. We assess temporal and spatial patterns of human occupation of high-altitude Andean deserts and neighboring areas comparing two of obsidian sources: Laguna del Diamante (34 S) and Cerro Huenul (36 S). The results indicate the existence of asymmetric distributions, particularly in the case of Laguna del Diamante. This evidence is used to assess the existence of dominant geographic vectors of human access and use of the Andean highlands. On this basis, we explore the analytical potential of minor sources for the study of human biogeography and organization of technology.

Interactions between human societies and the environment that they inhabit have been a controversial topic in archaeology for at least the past fifty years. Currently, modern theoretical approaches take this subject as a key issue in their research agenda. This paper presents a review of the main outcomes of several archaeological and multidisciplinary South American projects related to this theme. The case-studies discussed here are all located within arid settings, and can be grouped into three broad geographic areas: Puna (or Altiplano) of northwestern Argentina, Cuyo (west-central Argentina), and southern Patagonia. These regions cover a wide latitudinal range extending from 22° to 52° S. They were selected for comparison due to environmental similarities, and a common record of past climate impacts mainly related to the Medieval Climatic Anomaly (MCA) and the Little Ice Age (LIA). Although the impacts of these climatic changes were locally heterogeneous in their intensity and the quality of the available information is regionally variable, they provide a base-line for comparison and supra-regional integration. The integration of archaeological and palaeoenvironmental data on this broad supra-regional spatial scale allows us to identify interesting historical trajectories associated with particular time periods. As an example, there are some spatial rearrangements of large populations during the MCA, in the three areas. Additionally, there are variable patterns in the changes associated with the different social contexts that impose specific demographic and economic constraints. Finally, this study sets the basis for new questions and provides a guide to the methodological and theoretical issues that we need to address in order to answer them.