The effects of population history, climate, subsistence, and sex on human postcranial skeletal variation

Dunn, Tyler E

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https://hdl.handle.net/2142/115765 Copy

Description

Title

The effects of population history, climate, subsistence, and sex on human postcranial skeletal variation

Author(s)

Dunn, Tyler E

Issue Date

2022-04-21

Director of Research (if dissertation) or Advisor (if thesis)

Shackelford, Laura L

Doctoral Committee Chair(s)

Shackelford, Laura L

Committee Member(s)

• Konigsberg, Lyle
• Malhi, Ripan S
• Katz, David

Department of Study

Anthropology

Discipline

Anthropology

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Anthropology
• archaeology
• biology
• human evolution
• morphological variation
• genetic drift
• phenotypic variation

Abstract

Human skeletal variation is complex and multicausal. Adaptationist explanations of variation in postcranial skeletal morphology such as climate, mobility, and subsistence are common while genetic drift is rarely cited as a causal driver of variation, even though it is a fundamental driving force of evolution. Much of this work lies on the assumption that variation in any of these drivers is providing enough pressure on a population that it is driving directional selection. This dissertation investigates the influence of sex, climate, subsistence pattern, and neutral genetic effects on the phenotypes of the postcranial skeleton through the application of a single, mixed-effects model for high dimensional data. This model uses a large, widely distributed osteometric dataset, environmental variables, and evolutionary population histories to test the effect of population structure on a given metric and the role that the selective pressures examined play in that variation of that metric. The research presented here is three applications of a mixed effects model for assessing the relative degree to which morphology can be explained by climate, sex, and subsistence after partitioning out the relative effects of population structure. The methodological framework used in this dissertation utilizes an approach that has been employed in non-human biological systems for some time and broadens its application to modern human patterns of variation in order to better understand nonselective forces that play a role in producing variation. The outcome of this work shows the importance of incorporating - or at least acknowledging - neutral evolutionary processes in explanations of postcranial morphology. The mixed model approach used here has the ability to inform other aspects of skeletal variation, and recent work also furthered the exploration of the ontogenetic and plastic drivers of variation relative to population structure The ability to make definitive adaptationist conclusions between subsistence or climate and variation in the postcranial locomotor skeleton is limited when population structure is accounted. This model reifies the complexity of postcranial form and explores two factors that must be accounted for in studies of postcranial human variation: population structure and the appropriate selection of an osteometric proxy. This approach clarifies the role of population history in adaptationist explanations of human skeletal variation and has implications for the interpretations gleaned from postcranial skeletal variation. An investigation of the multiple drivers of morphological variation in the postcranial skeleton with respect to neutral evolutionary processes and environment is vital to creating a comprehensive understanding of the evolution of human skeletal variation.

Graduation Semester

2022-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Tyler E. Dunn

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