The genetic architecture and evolutionary function of human scalp hair morphology
Open Access
- Author:
- Lasisi, Tina Tina
- Graduate Program:
- Anthropology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- April 12, 2021
- Committee Members:
- Nina G Jablonski, Dissertation Advisor/Co-Advisor
Nina G Jablonski, Committee Chair/Co-Chair
George H Perry, Committee Member
Tim Ryan, Major Field Member
Mark Shriver, Dissertation Advisor/Co-Advisor
Mark Shriver, Committee Chair/Co-Chair
William Lawrence Kenney, Jr., Outside Member
George Havenith, Special Member
Tim Ryan, Program Head/Chair - Keywords:
- hair morphology
human evolution
biological anthropology
human scalp hair
human genetics
genetics
genomics
phenotypic variation - Abstract:
- Most hair follicles on the human body have evolved to be miniaturized, rendering us practically ‘naked’. Despite sparse body hair, we retain thick hair on our scalps that varies significantly among populations. Yet little is known of the evolutionary history of our scalp hair and its variation. It has been suggested that scalp hair, and tightly curled hair in particular, evolved to moderate thermal load in humans. However, this functional hypothesis has never been directly tested. Existing research on human hair variation has relied on subjective and qualitative descriptors of hair morphology and samples have been historically had a strong Eurocentric bias. Despite its relevance to several evolutionary hypotheses, scalp hair has yet to be studied in a comprehensive evolutionary, functional, and genetic framework. The functional work described in this dissertation revisits the recurrent question of the role of thermoregulation in shaping early human evolution. This work is the first to extensively investigate the potential role of scalp hair and variation in its morphology in modulating heat balance in humans. More broadly, the methods, samples, and hypotheses tested in this dissertation serve to replace racialized terminology and conceptions of human scalp hair variation. Current public discussions of human biological variation demonstrate that anthropologists must continue to oppose tendencies to perceive human variation in racial terms, and focusing on hair--one of the most visible and variable human traits--will provide anthropologists with evidence of how and why variation evolved. This dissertation synthesizes methods and knowledge from various disciplines with new data, generating an innovative perspective on both human origins and modern variation and laying the foundation for future work.