73 research outputs found
A GEOMETRIC MORPHOMETRIC ANALYSIS OF HOMINID MAXILLAE AND MANDIBLES
No full textFossil mandibular elements assigned to the taxon Australopithecus sediba were found at Malapa, South Africa. The mandibular elements have since been used to create a fully reconstructed version of the mandible of the animal. In order to better understand how fossil species separate with jaw bones an analysis will be done on extant species of great apes, gibbons, and humans. If the jaw bones do separate as expected it will be possible to then diagnose species based on jaw bone data, particularly if only data from one of the jaw bones is available
Aggressive Mimicry as a Human Hunting Strategy
No full textThe expansion of human cognition is a major question in the science of human origins. Several hypotheses have been proposed for its evolution, primarily the Foraging Brain and the Social Brain Hypotheses. Thus far, the Social Brain Hypothesis has much support based on its explanation for the evolution of Theory of Mind (ToM) in which social group size led to the development of `adept mind-reading and human deception in the human species. Alternatively, the Foraging Brain Hypothesis explains cognition through the lens of environmental pressure. Viewed as emphasizing separate sides of the same problem, I propose a potential pathway for the evolution of human deception independent of sociality that can be explained through ecological drivers: that of deception as a human hunting practice. Utilizing cross-cultural data gathered from the Human Relations Area File, I identified numerous (n=356) cross-cultural cases of the application of a hunting strategy in non-social hunting contexts across 143 cultures.
By comparing similar behaviors in non-human animals which utilize a hunting strategy known as aggressive mimicry, I suggest a potential pathway through which the evolution of deception and mind-reading may have taken place. Namely, whereby shifts in the ancestral environment and a change in the human dietary niche to rely on broad, hard-to-obtain foods led to a reliance on novel ways of capturing prey, including deception. Rather than theory of mind developing from sociality, I suggest social applications of mind-reading in humans could have theoretically followed the development of these applications for foraging contexts. This framework is also discussed in relation to paleoanthropological findings and human language evolution
Reconstructing the Habitat Mosaic of Australopithecus robustus: Evidence from Quantitative Morphological Analysis of Bovid Teeth
No full textThis research better resolves the environmental mosaic that is typically reconstructed for the A. robustus-bearing faunal assemblages of South Africa and evaluates whether A. robustus were habitat specialists or habitat generalists by testing whether they are associated with numerous, different reconstructed habitats, or if they can be associated with a single, more homogeneous habitat type. Determining the habitat preferences of A. robustus holds important implications for understanding the behavior of these hominins and, potentially, for understanding whether their ultimate extinction might have been climatically influenced, as fluctuations in the environments associated with the robust australopiths provide direct evidence about the responses of hominins to environmental change. To achieve this, a 2-dimensionsal morphometric tool was developed for accurately identifying the abundant bovid teeth that are found in direct association with the hominins using Elliptical Fourier Function Analysis. More accurate taxonomic identifications facilitate more precise estimates of the relative abundance of ecologically sensitive bovids, allowing for finer resolution when segmenting the various components of the reconstructed habitat mosaics. The fossil bovids abundances were compared across the assemblages over time in order to define the environmental mosaic in each assemblage and to determine if environmental heterogeneity existed across the assemblages. The relative abundances of the bovid fossil assemblages and A. robustus were compared to assess the habitat preferences of these hominins. A. robustus were not consistently associated with a particular habitat type suggesting that perhaps they were habitat generalists, capable of surviving in multiple types of habitats
An Analysis of Late Pleistocene Hominin Population Dynamics in Europe Using Ecological Niche Modeling Methods
No full textThis dissertation addresses questions concerning the patterns of population dynamics between Late Neandertals and early modern humans (EMHs) during the Late Pleistocene of Europe and the fluctuation of those patterns over time. Proposed models of Neandertal extinction and EMH expansion hypothesize certain patterns of behavioral responses to fluctuating climate and possible biogeographic features, such as the hypothesized Ebro River Frontier (EFM). Analyses designed to illuminate these potential patterns and test the presence of proposed biogeographic frontiers were conducted using the Genetic Algorithm for Rule-Set Prediction (GARP), originally designed for ecological research to model the geographic extent of suitable habitat associated with samples of presence-points and make well-informed hypotheses about the fundamental niche parameters of a species.
Three different paleoenvironmental reconstructions that shortly precede Neandertal extinction were used in this study to model the possible change in these patterns over time centered on Heinrich Event 4 (H4): 1) the Pre-H4 (43.3-40.2 ky cal BP), 2) the H4 (40.2-38.6 ky cal BP), and 3) the Post-H4 (38.6-36.5 ky cal BP). For the time period of each reconstruction, multiple experiments were run with different samples of locations absolutely dated to each time period designed to capture Neandertal and EMH presence. These samples move from more theoretically conservative groups of morphologically diagnostic fossil hominin remains to those which included Middle Paleolithic (MP) and Upper Paleolithic (UP) sites. The resulting consensus prediction models were statistically validated with a combination of Pearson���s p-value, cumulative binomial probabilities, and Partial-ROC analyses.
The results of this dissertation indicated that Neandertals and EMHs display different behavioral responses to the H4. Neandertal suitable habitat contracts during the H4 and is thereafter confined to southern Europe. The total area predicted for Neandertals does not reach its Pre-H4 levels again. EMH suitable habitat does not show the same southern confinement. The total area predicted for EMHs remains steady throughout the H4, a short glacial period, and increases during the Post-H4. The geographic overlap for Neandertal and EMH suitable habitat is the most extensive during the Pre-H4. Despite similar niches, Neandertals and EMHs display different behavioral responses to climatic fluctuations
The petrous portion of the human temporal bone: potential for forensic individuation
No full textIn this dissertation I evaluate the potential of the morphology of the
petrous portion of the human temporal bone as seen on axial CT scans of the
head as a means to generate identifications of fragmentary human skeletal
remains. The specific goals are threefold: (1) To investigate variability in the
shape of the petrous portion of the human temporal bone using two-dimensional
morphometric analysis; (2) to evaluate the reliability of the resultant method in
forensic identification; and (3) to consider the results within the framework of
Bayesian theory in light of recent rulings regarding the admissibility of forensic
testimony.
The data used in this research were collected from axial CT images of the
cranium. Two sets of images were collected for each of the 115 individuals in
the sample so that Euclidean distance comparisons could be made between
images of the same individual and images from different individuals. I collected two-dimensional coordinate data from 36 landmarks on each of the CT images
and calculated the distances between each of the coordinate points to generate
the data used in the statistical analyses.
I pared down this set of measurements using two different models
(referred to as the biological and PCFA models). The measurement sets of both
models were then compared to one another using nearest neighbor analysis, to
test their relative efficiency in matching replicate images to one another. The
results of both models were highly accurate. Three incorrect nearest neighbor
matches resulted from the biological model and 5 from the PCFA model. The
errors appear to have been the result of variation in the axial plane between the
first and second scans.
The results of the nearest neighbor comparisons were then considered
within the context of Bayes' Theorem by calculating likelihood ratios and
posterior probabilities. The likelihood ratios and posterior probabilities were very
high for both models, indicating that: 1) there is significant individual variability in
the measurements of the petrous portion used in this research, and 2) this
variation represents a high level of potential accuracy in the application of this
method in the identification of forensic remains
Slithering Through Space and Time: Uncoiling the Roles of Ecology and Phylogeny on Morphological Variation in Fossil and Extant North American Snakes Across Taxonomic, Temporal, and Spatial Scales
No full textAnthropogenic effects on the environment are an irrefutable actuality. Understanding how environmental changes affect organismal fitness, ecology, morphology, and evolution is critical for managing natural systems and conserving organisms through these changes. The study of morphological variation in skeletal elements provides an integrative route to bridge the gap between the past and the present of organism-environment interactions over long time scales. In this dissertation, I focus on snake morphological variation and its implications for taxonomy, phylogeny, ecology, and environmental change across space and time. I show that describing fossil snakes can be useful for understanding paleoenvironment, biogeography, and evolutionary patterns, epitomized by addressing a temporal gap for North American snakes, using vertebral morphology to identify taxa, and using proxy congenerics with climate data to estimate paleoclimate. The fossils and models support a hypothesis of gradual modernization in North American snakes occurring as Miocene environments grew drier and cooler in the Great Plains. I assess variation in snake middle trunk vertebrae with geometric morphometrics as a method for assigning snake vertebrae to taxon. Applying geometric morphometrics at multiple taxonomic levels indicated that a stepwise method may maximize the ability to identify snakes through vertebrae without diagnostic expertise. I demonstrate how combining external and skeletal morphological data with geographic, climatic, sex, and dietary data in the Western massasauga shows that morphological change within a species is better identified by combining the variation in both datasets, as variation gradated between the Southwest and Northeast. Finally, I construct a modern functional trait-environment framework for North American snakes using middle trunk vertebrae. I demonstrate that several aspects of shape variation are related to temperature-related variables and ecological province, and that combining multiple aspects produces better maximum likelihood models than any single aspect. My dissertation contributes to qualitative and quantitative methods to assess snakes and their interactions with the environment through time. This opens new avenues to append deep time data to our understanding of how snakes are functionally related to their environments, and what actions we can take to conserve and manage snakes in potential environmental futures
Brazos Santiago's Legacy: Implications of CRM on a Texas Maritime Landscape
No full textSituated in the Lower Rio Grande Valley (LRGV), Brazos Santiago was the deepest natural deep-water port for southernmost Texas and northernmost Mexico for over one hundred- and fifty-years. Due to its depth and position, it participated in international, national, and regional trade. Unfortunately, because of local harbor development and natural disasters the port was abandoned by 1930. Today it is known as 41CF4 by the Texas Historical Commission but it is largely forgotten by the public. However, the LRGV���s costal region is currently experiencing a surge of urbanization and commercialization which is threatening archaeological resources such as Brazos Santiago (41CF4). This poses the following question: has enough data on Brazos Santiago (41CF4) been collected to preserve the site���s legacy for future generations?
Overall, this dissertation sought to complete two objectives. The first objective was to analyze how archaeological surveys influenced Brazos Santiago���s (41CF4) interpretation and preservation, the recovery of cultural materials, and associated data, while gauging if this information is enough to preserve Brazos Santiago���s legacy for future generations. The second objective was to generate an authoritative source on the LRGV���s maritime heritage centering around Brazos Santiago. Maritime cultural landscape theory was used to frame this investigation and refine six channels of chapter specific research inquires. This dissertation utilizes archaeological, historical, ethnographic, and archival related data to fully contextualize Brazos Santiago���s place within the LRGV���s maritime landscape. This case study on Brazos Santiago can be used as a model on how the LRGV balances preserving the past while moving into the future and can be applied to other maritime landscapes experiencing similar shifts
Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa
No full textHomo naledi is a previously-unknown species of extinct hominin discovered within the Dinaledi Chamber of the Rising Star cave system, Cradle of Humankind, South Africa. This species is characterized by body mass and stature similar to small-bodied human populations but a small endocranial volume similar to australopiths. Cranial morphology of H. naledi is unique, but most similar to early Homo species including Homo erectus, Homo habilis or Homo rudolfensis. While primitive, the dentition is generally small and simple in occlusal morphology. H. naledi has humanlike manipulatory adaptations of the hand and wrist. It also exhibits a humanlike foot and lower limb. These humanlike aspects are contrasted in the postcrania with a more primitive or australopith-like trunk, shoulder, pelvis and proximal femur. Representing at least 15 individuals with most skeletal elements repeated multiple times, this is the largest assemblage of a single species of hominins yet discovered in Africa
Missionization and Shifting Mobility on the Southeastern Maya-Spanish Frontier: Identifying Immigration to the Maya Site of Tipu, Belize Through the Use of Strontium and Oxygen Isotopes
No full textThe early Colonial Period visita mission cemetery Tipu represents an important opportunity to understand the role mobility played in indigenous Maya resistance on the southeastern Maya-Spanish frontier. This dissertation seeks to identify the geographical origin of a subset (N=195) of the over 600 Postclassic and early Colonial period Maya buried at Tipu. As geographic and cultural frontier, Tipu experienced a dynamic history of fluctuating political alliances and was a pivotal player in frontier politics. Ethnohistorical records indicate that the remote frontier community of Tipu functioned as a place of refuge for a large southern exodus of indigenous Maya from the northern Yucatan escaping the hardships encountered in more populated regions under Spanish colonial control; to date little concrete evidence for this migration has been identified.
To test whether the frontier community of Tipu functioned as a haven for refugee Yucatec Maya, strontium (^87Sr/^86Sr) and oxygen (δ^18O) isotopes are used as geologic and climatic tracers to estimate potential childhood homelands for individuals buried at Tipu. Individuals comprising the Postclassic sample are used as a proxy to help establish the “local” range and to aid in the identification of shifts in mobility from the Postclassic to the Colonial period. A comparison of ^87Sr^/86Sr and δ^18O data from the Postclassic and Colonial period samples shows an increase in the quantity of Colonial period individuals falling within the “local” range, as well as a dramatic increase in the total variability and range of observed isotope values in the Colonial period. Nearly two-thirds of the Colonial Tipu population were classified as non-local, suggesting that Tipu was primarily composed of recent, first-generation migrants; a highly mobile population is consistent with ethnohistoric records for Tipu. These results indicate Spanish colonialism resulted in a significant and swift shift in mobility of the indigenous Maya, even in more peripheral frontier regions like Tipu, and underscores Tipu’s importance as a refugee for fleeing Maya. The presence of migrants from both Spanish and Maya held territories provides evidence for the fluidity of the Maya-Spanish frontier and Tipu’s importance as a gateway for trade between the two territories. Sex-based differences between migrants and locals are observed, and possible spatial patterns in the distribution of isotope values are explored. This research provides an increased realization of indigenous reactions to early European colonialism in frontier areas
Linneaus) cave caching related to anti‐theft behaviour in the John Nash Nature Reserve, South Africa
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