Dissertations, Theses, and Capstone Projects

Date of Degree

9-2025

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy

Program

Biology

Advisor

David Lahti

Committee Members

Carolyn Pytte

Larissa Swedell

Elizabeth Derryberry

Andrew Whiten

Subject Categories

Behavior and Ethology | Biology | Ecology and Evolutionary Biology | Evolution | Other Ecology and Evolutionary Biology

Keywords

Cultural Evolution, Cultural Lability, Birdsong, Vocal Communication, Animal Culture, Sexual Selection

Abstract

Cultural evolution, or the study of change over time in socially learned traits, has gained traction as a field since the theoretical advancements of Robert Boyd, Peter Richerson, L.L. Cavalli-Sforza and Marcus Feldman in the 1980s, attracting researchers from a range of disciplines including evolutionary biology, anthropology, primatology, ornithology, psychology, and the humanities. The diversity of thought and approach has led to disagreement surrounding the shape that cultural change typically takes, and the contributions of novelty and individual learning strategies to the process.

Using oscine birdsong as a focal point, this dissertation provides a multidisciplinary synthesis of theoretical and empirical work in cultural evolution, attempting to tease apart some of the independent threads that interact to create observed patterns in socially learned traits. I first explore the variables that determine the rate at which a cultural trait evolves, namely its “cultural lability”. These include a variety of demographic, ecological, and functional considerations that produce different song outcomes in different species. I establish that cultural asynchrony, wherein facets of a cultural trait evolve at distinct rates according to function, is the norm in species that learn socially, and I suggest several avenues for further inquiry. I next challenge the idea, put forward by several theorists, that cumulative cultural evolution, i.e. increases in the efficacy of cultural traits over time, can describe both pragmatic traits like technology and aesthetic ones like fashion. I outline the distinct evolutionary patterns associated with each category, and I argue that certain trends resembling enhancements in aesthetic cultural traits are the result of sexual selection on noncultural qualities, and therefore cannot be the products of cumulative cultural evolution. Finally, I explore the relationships between creativity (which produces the traits that are assimilated into animal cultures), patterns in pragmatic and aesthetic cultural evolution, and virtuosity (i.e. the differentiation of individuals based on skill). My last chapter explores this interplay in oscine songbirds but extends the discussion to humans and nonhuman primates, suggesting a broad theoretical framework in which to consider the many attributes that weave together to keep cultures evolving.

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