This composite photograph depicts the measurement of oxygen consumption during walking in quadrupedal chimpanzees, bipedal chimpanzees, and humans. Metabolic and biomechanical comparisons of human and chimpanzee walking indicate that our earliest ancestors may have reaped an energetic benefit by adopting a bipedal gait.

Just as our culture and material history tells us a great deal about who we are and where we’ve come from, a rich evolutionary history lies written in our bones. To try to better understand this history, my research investigates how evolution has shaped our anatomy and physiology. Much of my work focuses on longstanding questions in human evolution: How and why did hominins begin walking upright? Why was our evolutionary trajectory so different from that of other apes? What behavioral and physiological adaptations made it possible for our ancestors to spread out of the tropics to become the wide-ranging species we are today?

To investigate these questions, I study the relationships of locomotor anatomy, gait, and energy use in humans, chimpanzees, and a host of other species. Most of this work takes place in the lab, using state-of-the-art motion capture and energetics equipment to study locomotion and energy use. Using this approach, I’m able to test ideas regarding form, function, and ecology, and use these results to shed light on our evolutionary history. For example, lab-based studies of limb length and locomotor cost - measuring oxygen consumption and gait in humans, goats, and dogs walking and running on a treadmill - enabled me to test a new biomechanical model of walking energetics in humans and other animals. The results indicate that longer legs lead to less costly locomotion for all terrestrial animals, a result with important implications for understanding the dramatic increase in leg length seen in the earliest members of our genus. More recently, I’ve been investigating walking cost, gait, and anatomy in chimpanzees, a living model of our apelike forebears. This work has enabled my collaborators and me to test the idea that walking upright gave early hominins a critical evolutionary advantage by lowering the energy cost of locomotion.

My work also takes me to the Republic of Georgia, where I work as a member of the Dmanisi research team. Dated to 1.8 million years old, this exciting site provides the earliest evidence of human ancestors outside of Africa. Studying the hominin fossils from Dmanisi provides a great way to test ideas born in the lab and helps direct my laboratory work toward exciting new questions in human evolution.