The Cultural Evolution of Savannah Sparrow Song by Summer Keating ’25

The Cultural Evolution of Savannah Sparrow Song: The Power Law, Random Drift, and Parallels to Human Speech Structure by Summer Keating ’25, Wednesday April 16, 1:00 – 1:50pm, North Science Building 113, Mathematics Thesis Defense

Abstract: Cultural evolution is the process through which traits and behaviors change over time. This thesis will study the cultural evolution of birdsong from Savannah sparrow populations in Kent Island, New Brunswick, Canada, and Williamstown, MA. It develops a neutral model (based on random drift), examines how much drift alone explains the evolution of birdsong, and uses the power law to explore the similarities between the evolution of Savannah sparrow bird song and human speech development. The frequency distribution of song variants in the Williamstown population of Savannah sparrows closely fits a power law curve, and a broader categorization of middle notes fits a power law curve better than more specific middle note classes. These findings suggest that the evolution of Savannah sparrow song shares fundamental aspects of human speech development, with the close fit to a power law curve likely indicating effective cultural transmission rather than random drift.