These paleoenvironmental proxies sample past environments at geographic scales that are often regional. The GCFR flora is hyper-diverse, and glacial climate change-driven impacts on local vegetation could have been highly variable over relatively small geographic scales. Proxy records that are circumscribed in their geographic scale are thus key to our understanding of ancient environments at particular MSA archaeological localities.
Micromammal fossil teeth are now recognized as an abundant potential reservoir of paleoenvironmental proxy data at an extremely local scale. This study analyzed modern micromammal teeth obtained from raptor pellets at three locations on the south coast. Stable carbon isotope analysis indicates that the modern micromammals from the taxa sampled consume a wide range of δ13Cplant on the landscape when it is available, and thus stable carbon isotope analysis of micromammal teeth should act as a proxy for the range of available δ13Cdiet in a circumscribed area of vegetation.
Micromammal stable carbon isotope data obtained from specimens from one of the few well-dated MIS6-MIS5 sequences in the region (Pinnacle Point sites 13B, 30, and 9C). δ13Cenamel values for the taxa sampled indicate diets that are primarily C3, and there is almost no evidence for a dietary C4 grass component in any of the sampled specimens. This indicates that, at a minimum, pockets of C3 vegetation associated with the GCFR were likely available to hunter-gatherers at Pinnacle Point throughout the Middle and Late Pleistocene.
This project studied the role and importance of lithic raw materials in the technological organization of foragers by focusing on why lithic raw material selection sometimes changed when the behavioral and environmental context changed. The study used the Pinnacle Point (PP) MSA record (MIS6-3) in the Mossel Bay region, South Africa as the test case. In this region, quartzite and silcrete with dramatically different properties were the two most frequently exploited raw materials, and their relative abundances change significantly through time. Several explanations intertwined with major research questions over the origins of modern humans have been proposed for this change.
Two alternative lithic raw material procurement models were considered. The first, a computational model termed the Opportunistic Acquisition Model, posits that archaeological lithic raw material frequencies are due to opportunistic encounters during random walk. The second, an analytical model termed the Active-Choice Model drawn from the principles of Optimal Foraging Theory, posits that given a choice, individuals will choose the most cost effective means of producing durable cutting tools in their environment and will strategically select those raw materials.
An evaluation of the competing models found that lithic raw material selection was a strategic behavior in the PP record. In MIS6 and MIS5, the selection of quartzite was driven by travel and search cost, while during the MIS4, the joint selection of quartzite and silcrete was facilitated by a mobility strategy that focused on longer or more frequent stays at PP coupled with place provisioning. Further, the result suggests that specific raw materials and technology were relied on to obtain food resources and perform processing tasks suggesting knowledge about raw material properties and suitability for tasks.
This study tested hypotheses using two diet categorizations: total consumption percent and food material properties (FMPs). The first hypothesis that cortical bone area (CA) and section moduli (bone strength) are positively correlated with masticatory loading tests whether CA and moduli measures were greatest anteriorly and decreased posteriorly along the arch. The results found these measures adhered to this predicted pattern in the majority of taxa. The second hypothesis examines sutural complexity in the zygomaticotemporal suture as a function of dietary loading differences by calculating fractal dimensions as indices of complexity. No predictable pattern was found linking sutural complexity and diet in this primate sample, though hard object consumers possessed the most complex sutures. Lastly, cross-sectional geometric properties were measured to investigate whether bending and torsional resistance and cross-sectional shape are related to differences in masticatory loading. The highest measures of mechanical resistance tracked with areas of greatest strain in the majority of taxa. Cross-sectional shape differences do appear to reflect dietary differences. FMPs were not correlated with cross-sectional variables, however pairwise comparisons suggest taxa that ingest foods of greater stiffness experience relatively larger measures of bending and torsional resistance. The current study reveals that internal and external morphological factors vary across the arch and in conjunction with diet in primates. These findings underscore the importance of incorporating these mechanical differences in models of zygomatic arch mechanical behavior and primate craniofacial biomechanics.
The role that climate and environmental history may have played in influencing human evolution has been the focus of considerable interest and controversy among paleoanthropologists for decades. Prior attempts to understand the environmental history side of this equation have centered around the study of outcrop sediments and fossils adjacent to where fossil hominins (ancestors or close relatives of modern humans) are found, or from the study of deep sea drill cores. However, outcrop sediments are often highly weathered and thus are unsuitable for some types of paleoclimatic records, and deep sea core records come from long distances away from the actual fossil and stone tool remains. The Hominin Sites and Paleolakes Drilling Project (HSPDP) was developed to address these issues. The project has focused its efforts on the eastern African Rift Valley, where much of the evidence for early hominins has been recovered. We have collected about 2 km of sediment drill core from six basins in Kenya and Ethiopia, in lake deposits immediately adjacent to important fossil hominin and archaeological sites. Collectively these cores cover in time many of the key transitions and critical intervals in human evolutionary history over the last 4 Ma, such as the earliest stone tools, the origin of our own genus Homo, and the earliest anatomically modern Homo sapiens. Here we document the initial field, physical property, and core description results of the 2012–2014 HSPDP coring campaign.
We have little knowledge of how climatic variation (and by proxy, habitat variation) influences the phylogenetic structure of tropical communities. Here, we quantified the phylogenetic structure of mammal communities in Africa to investigate how community structure varies with respect to climate and species richness variation across the continent. In addition, we investigated how phylogenetic patterns vary across carnivores, primates, and ungulates. We predicted that climate would differentially affect the structure of communities from different clades due to between-clade biological variation. We examined 203 communities using two metrics, the net relatedness (NRI) and nearest taxon (NTI) indices. We used simultaneous autoregressive models to predict community phylogenetic structure from climate variables and species richness. We found that most individual communities exhibited a phylogenetic structure consistent with a null model, but both climate and species richness significantly predicted variation in community phylogenetic metrics. Using NTI, species rich communities were composed of more distantly related taxa for all mammal communities, as well as for communities of carnivorans or ungulates. Temperature seasonality predicted the phylogenetic structure of mammal, carnivoran, and ungulate communities, and annual rainfall predicted primate community structure. Additional climate variables related to temperature and rainfall also predicted the phylogenetic structure of ungulate communities. We suggest that both past interspecific competition and habitat filtering have shaped variation in tropical mammal communities. The significant effect of climatic factors on community structure has important implications for the diversity of mammal communities given current models of future climate change.
Some broad generalizations have been made; most work in the region is concerned primarily with descriptive and definitional issues rather than efforts to explain past human behavior or human-environmental interactions. Modern research directed towards understanding human adaptation to different environments remains in its infancy. Grounded in the powerful conceptual framework of evolutionary ecology and utilizing recent methodological advances, this work has shown that shifts in land-use strategies changes the opportunities for social and biological interaction among Late Pleistocene hominins in western Eurasia, bringing with it a plethora of important consequences for cultural and biological evolution.
I employ, in my Dissertation, theoretical and methodological advances derived from human behavioral ecology (HBE) and lithic technology organization to show how variability in lithic technology can explain differences in technoeconomic choices and land-use strategies of Late Pleistocene foragers in Romanian Carpathians Basin and adjacent areas. Set against the backdrop of paleoenvironmental change, the principal questions I addressed are whether or not technological variation at the beginning of the Upper Paleolithic can account for fundamental changes at its end.
The analysis of the Middle and Upper Paleolithic strata, from six archaeological sites, shows that the lithic industries were different not because of biocultural differences in technological organization, landuse strategies, and organizational flexibility. Instead the evidence suggests that technoeconomic strategies, the intensity of artifact curation and how foragers used the land appear to have been more closely related to changing environmental conditions, task-specific activities, and duration of occupation. This agrees well with the results of studies conducted in other areas and with those predicted from theoretically-derived models based on evolutionary ecology. My results lead to the conclusion that human landuse effectively changes the environment of selection for hominins and their lithic technologies, an important component of the interface between humans and the natural world. Foragers move across the landscape in comparable ways in very different ecological settings, cross-cutting both biological morphotypes and prehistorian-defined analytical units.