Bone shape across animal species is the result of evolution (passing down traits to offspring) and adaptation (change of shape during life). This research investigates how bones change shape in response to different behaviors and environments, using deer mice as a model system. Scientists will study two closely related mouse species—one that burrows underground and one that does not—to understand whether bone structure is primarily determined by genetics passed down through evolution or by physical activity during an animal's lifetime. By raising mice in environments that either allow or prevent digging, and using cutting-edge X-ray technology to film their movements in real-time, researchers will discover how specific behaviors reshape bones. This work addresses a fundamental question in biology about how form follows function in living organisms. The findings will have important implications for human health, particularly in understanding bone diseases, aging, and the role of exercise in maintaining strong bones throughout life. The project will also advance scientific infrastructure by pioneering new imaging technology that can capture detailed bone and muscle movements in very small animals, opening doors for future biomedical research. Additionally, the research will train high school, undergraduate, and graduate students in laboratory techniques and create educational materials for teachers to help students understand evolution, physiology, and engineering principles t