This dissertation comprises five, self-contained chapters, each focused on an issue at the intersection of ethical theory and the biological sciences. Chapter 1 enters into an on-going debate over whether evolutionary explanations for widespread patterns of basic evaluative judgments threaten certain kinds of normative realism. I argue that normative realism can be shown to be compatible with a plausible view of the evolution of human evaluative judgment. Chapter 2 brings together several parallel lines of thought in contemporary epistemology, philosophy of biology, and philosophy of mind on the nature of belief in order to build a framework for considering how and why selection might favor certain kinds of representational states in humans. Chapter 3 focuses on an evolutionary puzzle about guilt proneness in humans, offering two solutions to the puzzle, one rooted in an individual-level selectionist account, the other in a group-level account. Chapter 4 develops an approach to genetic counseling that attends to the manifold ways in which patients are vulnerable to manipulation, coercion, and social pressure during genetic counseling. Finally, Chapter 5 considers whether Aquinas' moral epistemology is threatened by contemporary anti-essentialist views of human nature.