Investigating crop plant origins in the Americas using ancient DNA and experimental plant developmental research

Open Access
Author:
Kistler, Logan Jonas
Graduate Program:
Anthropology
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
April 27, 2012
Committee Members:
  • Lee Ann Newsom, Dissertation Advisor
  • Beth Shapiro, Committee Member
  • George Robert Milner, Committee Member
  • Dean R. Snow, Committee Member
Keywords:
  • Plant domestication
  • Ancient DNA
  • North American Archaeology
  • Chenopodium
  • Lagenaria
  • Bottle gourd
  • Cucurbita
  • phytoliths
Abstract:
The integration of molecular biology and plant physiology into archaeology allows us to more comprehensively and directly address difficult questions regarding past human activity. The former can be used to trace plant and animal domestication and phylogeography, demographic histories, human dispersal and demographics, etc. The latter is inexorably linked with plant life history and, eventually, site formation processes and the physical composition of the archaeological record. This dissertation comprises three individual studies: Parts 1 and 2 utilize ancient and modern DNA to elucidate the domestication histories of two important North American crop plants, chenopod (Chenopodium berlandieri Moq., Chenopodiaceae), and bottle gourd (Laganeria siceraria [Molina] Standl., Cucurbitaceae). Part 3 is an experimental study conducted to understand the effects of pathogenic stress on the formation of silica phytoliths in gourd/squash (Cucurbita pepo L., Cucurbitaceae), and potential implications for archaeological phytolith analyses. In Part 1, I test whether chenopod, an important prehistoric starchy seed crop in the Eastern Woodlands of North America was locally and independently domesticated, or whether it was introduced from Mesoamerica, where morphologically identical crops are grown today. I conclude that it was native to the Eastern Woodlands, and argue that this finding strengthens the existing evidence for eastern North America as an entirely independent center of plant domestication. In Part 2, I test competing hypotheses regarding the arrival and proliferation of bottle gourds, one of the world’s earliest and most broadly distributed crop plants, in the New World. I conclude that bottle gourds traveled on ocean currents from their native Africa to the New World during the Pleistocene, established genetically diverse naturalized populations, and underwent multiple domestication events in the Americas during the Holocene. In Part 3, I extract and analyze silica phytoliths from wild gourd fruits grown in controlled experimental conditions to test for morphological changes driven by two common diseases. I find that pathogenic stress has the potential to significantly impact phytolith size in ways that might confound archaeological phytolith analyses. I argue that extensive experimental assessment of ecological effects on phytolith morphology is in order to strengthen archaeobotanical phytolith analyses.