There is debate about how fossil hominin pedal morphology relates to terrestrial habits. Were early hominins adapted to a bipedal lifestyle with a significant arboreal component, or were they more dedicated to a terrestrial lifestyle? The proximal articular surfaces of the metatarsals (MT) are examined in Gorilla, Pan, Hylobates, and habitually shod and unshod Homo using three-dimensional morphometrics. The results for MT 1 show three trends. OH 8 (Homo habilis) is indistinguishable from humans, specimens SKX 5017 and SK 1813 (Paranthropus robustus) are apelike, and all other fossil 1st metatarsals are intermediate in shape between humans and apes. The MT 2 and MT 3 analyses show that humans have a narrower surface that is expanded in the plantar aspect relative to apes. These features increase joint stability for the human longitudinal arch. The MT 2 fossils for Stw 573d (Little Foot) and OH 8 are humanlike. The MT 2 specimen of SKX 247 (possibly Paranthropus) is apelike, while all other MT 2 fossils are intermediate between humans and apes. In the MT 3 analysis, Stw 387, Stw 496, Stw 388, and OH 8 metatarsals are humanlike in shape, while Stw 435 and Stw 477 are intermediate between humans and apes. The MT 3 surface of Hylobates is markedly convex, suggesting that the midfoot break in gibbons extends to include this joint in addition to the MT 4 and MT 5 tarsometatarsal joints. The results of the MT 4 analysis show a highly convex surface in apes, with Hylobates extending further to the dorsal aspect of this metatarsal, with a greater range of motion at the midfoot break compared to the African apes. The MT 4 specimens of OH 8 and Stw 628 show greater morphological affiliation with humans. The MT 5 analysis shows that Pan and Hylobates have a medio-laterally extended and concave articular surface that is convex in the dorso-plantar plane. The two human groups are narrower and flatter in the medio-lateral plane, with a little dorso-plantar convexity. There is overlap in shape patterns between groups in the MT 5 analysis. Greatest similarity is between humans and Gorilla. The MT 5 fossil specimens tend to show closer affiliation to humans and Gorilla.

A century of intermittent archaeological research in the Azraq Basin of the eastern desert of Jordan has demonstrated that a long period of hominin occupation exists in this environmentally inhospitable region during the Pleistocene. Recent excavations at the site of Shishan Marsh 1 in the Azraq Basin have uncovered several artifact-bearing layers that correspond to the Middle (266 ± 40 kya) and Upper (125 ± 12 kya) Pleistocene. An examination of paleoclimatic data from this period indicates predominantly warm and dry conditions in the region and a gradual reduction of water availability. These factors forced hominins to modify their resource acquisition strategies and exploit the receding spring- and wadi-fed Azraq wetlands. This dissertation investigates the nature of lithic procurement strategies practiced by hominins at Shishan Marsh 1, a Middle-Upper Pleistocene site in the former wetlands, during periods of environmental stress. It involves a provenance analysis of sources within the region and a sample of lithic artifacts from Shishan Marsh 1 through laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The results indicate that the artifacts were procured from local and regional sources and likely through embedded procurement in an effort to provision individuals. They further provide insight into the nature of survival within the Azraq Basin, as hominin groups performed tethered mobility whereby they contracted around the Azraq wetlands. In this case, this stable water source operated as a desert refugium for hominins within the Azraq Basin. / Graduate / 2021-11-13

2006 Dozier Award Winner / Agent-based models can provide paleoanthropologists with a view of behavioral dynamics and site formation processes as they unfold in digital caricatures of past societies and paleoenvironments. This paper argues that the agent-based methodology has the most to offer when used to conduct controlled, repeatable experiments within the context of behavioral laboratories. To illustrate the potential of this decidedly heuristic approach, I provide a case study of a simple agent-based model currently being used to investigate the evolution of Plio-Pleistocene hominin food sharing in East Africa. The results of this null model demonstrate that certain levels of ecological patchiness can facilitate the evolution of even simple food sharing strategies among equally simple hominin foragers. More generally, they demonstrate the potential that agent-based models possess for helping historical scientists act as their own informants as to what could have happened in the past.

African climate changed considerably throughout the Pleistocene (2.588 million (Ma) to 12 thousand years ago (ka)). The timing, rate, and magnitude of past climate change across the continent impacted the evolutionary and migratory history of many mammalian species, including hominins. Investigating paleoclimatic variability through time at local and regional scales allows for an assessment of the extent to which climate change affected hominin evolution in Africa. This dissertation presents three approaches for increasing the understanding of past climate change in Africa. One method is to critically synthesize the existing literature of African climate (n=85) and hominid demography (n=64) over a restricted time frame (150 ka to 30 ka) and specific spatial scale (regional). Results from this study are two-fold: 1) climate change in Africa during this period was variable by region, responding to different climate-forcing mechanisms, and 2) changes in population and climate were asynchronous and likely created alternating opportunities for migration into adjacent regions, including hominin migrations out of Africa (~140-80 ka). The second approach is to evaluate modern ecological relationships between species and their environment to better quantify interpretations of paleoecological records. A modern distribution study of 33 ostracode species from 104 sites in the southwest arm of Lake Malawi suggest that depth-dependent variables likely define species niches. Relationships between ostracodes, fish and the green algae Botryococcus, were used to inform the paleoecological interpretations in the third study of this dissertation. Additional results suggest that macrocharcoal is likely delivered to the lake basin via river rather than wind-borne methods. The third approach involves primary analysis of climatic indicators from the sedimentary record to chronicle paleoecological and paleoenvironmental change at the basin scale through time. Results from a 380.7 meter-long sediment core recovered from Lake Malawi indicate a change of state likely caused by local tectonism, which affected ostracode assemblages, but had little effect on lake level history through time. Furthermore, the local hydroclimate of Lake Malawi alternately covaried with global glacial/interglacial cycles and local insolation maxima over the past 1.25 Ma. The magnitude and frequency of hydroclimatic variability in the watershed will be further assessed in future research.

This thesis tests models on the dispersal of hominin populations in the Upper Pleistocene, specifically in relation to the Arabian Peninsula. It does so by conducting a quantified comparison of lithic assemblages from northeast Africa and southwest Asia. Lithic data from new excavations at the Jubbah Palaeolake in northern Saudi Arabia is compared to assemblages from Ethiopia, Sudan, Egypt, Jordan, Iran, Oman and other localities in Saudi Arabia. This is the first detailed inter-regional study of this area for Marine Isotope Stages 5 to 3, a critical spatial and temporal context in debates on both early modern human and Neanderthal demography and dispersal. The spatial and temporal character of the rich Arabian archaeological record correlate with emerging evidence for environmental change in Arabia; in particular the repeated dating of archaeological contexts to periods of climatic amelioration suggests that demographic growth was associated with periods of increased precipitation. The various factors influencing lithic variability and the methodologies by which they can be elucidated are reviewed. In particular this highlights the need for quantified and comparative analyses. A variety of analytical approaches are applied in this thesis, including the use of Correspondence and Principal Components Analyses to develop a nuanced view of lithic variability. Variability in cores is shown to largely reflect the related factors of size and reduction intensity. With analyses of debitage and retouched lithics a broadly similar picture emerges: assemblages which are heavily reduced have small cores and blanks and higher levels of retouch, and elements of shape variation also change in relation to reduction intensity. Elements of residual variability may reflect cultural differences. While it is felt that the evidence presented broadly orientates the Upper Pleistocene Middle Palaeolithic of Arabia to dispersals from Africa, this suggestion is subsumed with a problematization of using lithic evidence to understand dispersals. Aside from the need for further dated archaeological material from Arabia and surrounding countries, lithic analyses need to more thoroughly consider factors such as reduction intensity if we are to make robust inferences on population dispersals.

Ever since Darwin claimed that expanding savannas were the driving force behind humanity's divergence from other apes, our understanding of human evolution has been inextricably linked to the environmental context in which our ancestors evolved. This dissertation explores various aspects of the use of one method of paleoenvironmental reconstruction -- bovid ecomorphology -- and provides new data on paleoenvironmental conditions in the Omo Shungura Formation (Plio-Pleistocene, Ethiopia). Chapter 2 uses phylogenetic simulations to explore the performance of Discriminant Function Analysis (DFA) on simulated ecomorphological data containing phylogenetic signal. DFA is shown to "over-perform" in situations in which predicted and predictor variables both contain phylogenetic signal. Phylogenetic Generalized Least Squares (PGLS) is shown to be a very useful technique for explicitly testing functional hypotheses in ecomorphology while controlling for phylogenetic signal and body size. Chapter 3 presents a functional analysis of the bovid astragalus, which is one of the most commonly preserved bones in the fossil record. Several functional hypotheses linking habitat-specific locomotor performance with the morphology of the astragalus are tested using PGLS. Strong support is found for three of these hypotheses. Thus, the astragalus is shown to be a useful ecomorphological predictor element, a point that is confirmed by the DFA analyses in Chapter 4. Chapter 5 provides new paleoenvironmental data on the Omo Shungura Formation based on habitat reconstructions from astragalar ecomorphology in addition to dietary reconstructions based on dental mesowear. Astragalar data point to a major environmental shift beginning ~2.58 Ma, which is later in time compared with some prior habitat reconstructions using different methods. Furthermore, astragalar data show environmental fluctuations of similar magnitude later in the sequence. Mesowear data on the Shungura Tragelaphini do not offer evidence for any significant grazing adaptation, in spite of relatively high carbon isotope signatures reported based on studies of tooth enamel. These data raise questions regarding the diet of fossil Tragalephini. / text

In the present body of work two primary subjects have been addressed, both individually and in their correspondence, namely 1) the potential for Neanderthals to have contributed to the Modern Human population, and 2) the genetic diversity of one of the most prehistorically impactful human popuations, the Armenians. The first subject is addressed by assessing 1000 mutations in 384 current humans, particularly for those mutations which appear to derive from the Neanderthal lineage. Additionally, the validity of the Neanderthal sequences themselves is evaluated through alignment analysis of fragementary DNA derived from the Vindija Cave sample. Armenian genetic diversity is analyzed through the autosomal short tandem repeats, y-chromsome single nucleotide polymorphisms, and y-chromosome short tandem repeats. The diversity found indicates that Armenians are a diverse group which has been genetically influenced by the various migrations and invasions which have entered their historic lands. Further, we find evidence that Armenians may be closely associated with the peopling of Europe.

Previous research on the biomechanics of tool use has focused heavily on traits correlated with locomotion, tool manufacturing, and habitual tool use. Features like the breadth of the metacarpals, relative length of the thumb, styloid process of the third metacarpal, and the breadth of the apical tufts are skeletal features associated with the use and development of stone tools. However, there are many traits of the distal forelimb that may also be correlated directly with the development and use of tools. The purpose of this research is to analyze morphological features of the hands and compare them to features of the arm in humans, fossil Homo and the great apes to understand how the hominin distal arm functions as a mosaic in response to the use of stone tools. The results indicate a separation between tool-users and non-tool users when all distal forelimb dimensions are examined. Omo 40-19 falls closer to non-tool users when univariate plots of ulna length and breadth are examined. Ratios of hand measurements to radius length are better at polarizing the tool-users from non-tool users than are hand dimensions to ulna length ratios. These results highlight the role of the radius in stabilizing the hand during stone tool production.

abstract: Climate and environmental forcing are widely accepted to be important drivers of evolutionary and ecological change in mammal communities over geologic time scales. This paradigm has been particularly influential in studies of the eastern African late Cenozoic fossil record, in which aridification, increasing seasonality, and C4 grassland expansion are seen as having shaped the major patterns of human and faunal evolution. Despite the ubiquity of studies linking climate and environmental forcing to evolutionary and ecological shifts in the mammalian fossil record, many central components of this paradigm remain untested or poorly developed. To fill this gap, this dissertation employs biogeographical and macroecological analyses of present-day African mammal communities as a lens for understanding how abiotic change may have shaped community turnover and structure in the eastern African Plio-Pleistocene. Three dissertation papers address: 1) the role of ecological niche breadth in shaping divergent patterns of macroevolutionary turnover across clades; 2) the effect of climatic and environmental gradients on community assembly; 3) the relative influence of paleo- versus present-day climates in structuring contemporary patterns of community diversity. Results of these papers call into question many tenets of current theory, particularly: 1) that niche breadth differences (and, by extension, their influence on allopatric speciation) are important drivers of macroevolution, 2) that climate is more important than biotic interactions in community assembly, and 3) that communities today are in equilibrium with present-day climates. These findings highlight the need to critically reevaluate the role and scale-dependence of climate in mammal evolution and community ecology and to carefully consider potential time lags and disequilibrium dynamics in the fossil record. / Dissertation/Thesis / Doctoral Dissertation Anthropology 2018

Chimpanzees spend ~40% of their day chewing fruits, seeds, and tough leaves and pith, while in contrast modern humans spend significantly less time eating (5%), and the foods that they consume are extremely soft and processed. How have these differences, especially the advent and increasing use of foods processing techniques, influenced masticatory effort and ultimately the morphology of the jaws and teeth? This dissertation addresses this question by measuring the effects that early hominin food processing methods (slicing, pounding, and roasting) have on food material properties, masticatory performance and functional integration of the teeth and jaws. Using standard testing techniques, the material properties of plant tubers and meat were quantified. Processing had contrasting effects on the properties of these foods, and were correlated with masticatory performance changes measured in human experiments. Mechanical processing techniques decreased tuber toughness, leading to lower chew force (CF). Roasting further decreased tuber toughness and other material properties, which led to lower comminution efficiency (CE) and CF. In direct contrast to tubers, mechanical processing techniques did not alter meat toughness, yet did increase CF and CE. Roasting the meat also increased CF and CE, likely because of higher toughness and stiffness, coupled with less elastic energy loss. The generation of lower masticatory forces resulting from processing have undoubtedly affected cranio-dental morphology. In particular, it is hypothesized that forces functionally integrate the masticatory system, and reduced forces, especially in modern human populations, lead to malocclusions (dis-integration). An animal experiment was performed to test this hypothesis, and the results indicate that masticatory effort (eating hard or soft foods) coordinates jaw and dental growth. Further testing the hypothesis, the effects of morphology on masticatory function were studied by coupling subject masticatory performance with occlusal scores. Multiple regressions of occlusion and tooth size explained a high proportion of masticatory performance variance (significantly more than tooth size alone), suggesting that occlusal integration does indeed affect masticatory function. Taken together, the results of this dissertation document the significant reductions in hominin masticatory forces and changes in cranio-dental growth and integration that may have resulted from the use of food processing techniques. / Human Evolutionary Biology