Overall Research Program:

Our lab uses a range of integrative methods, including analyses of fossil hominin anatomy, comparative biology, laboratory experiments, and fieldwork, to answer two key over-arching questions:

1) How and why have locomotion and aerobic activity levels changed during human evolution?

2) What are the impacts of our evolutionary history on physiology, neurobiology, life history, and health?

In general, our work falls into three overlapping areas:

Evolutionary Biomechanics and Physiology

Our lab uses comparative biomechanics and physiology to reconstruct patterns of physical activity during human evolution. Our basic approach is to identify links between anatomy and locomotor performance (speed, energy costs, endurance, etc.) in living taxa. We use these links to understand locomotor performance in the fossil record. Recent projects include:

 

• We linked foot anatomy to the energy costs of running in living humans, showing that the length of the calcaneal tuber determines the amount of energy stored in the Achilles tendon. We used this morphological link to reconstruct running performance in fossil taxa.
• We compared footprints experimentally generated in our lab with 3.6 million years old fossil footprints from Laetoli, Tanzania. We showed that the Laetoli prints were made by bipeds walking with biomechanics similar to our own, rather than more ape-like biomechanics.

collaborators: Herman Pontzer, Adam Gordon, Daniel Lieberman

 

Neurobiology, Physiology, and Exercise

Our lab is also interested in the interaction between physical activity, neurobiology, and physiology in extant taxa, including humans. Work in our lab (and others) suggests that aerobic activity increased greatly during human evolution. We are currently examining the effects of endurance exercise on the evolution of the human brain with a specific focus on how and why physical activity improves cognitive health across the lifespan. Recent projects include:

 

• The evolution of the runner's high. We are testing the hypothesis that selection used neurobiological rewards to encourage endurance exercise in humans and other mammals.
• The correlation between exercise and brain size across mammals. Exercise leads to neurogenesis in the adult hippocampus and our lab is currently investigating the evolutionary links between exercise, neurobiology, and cognitive performance (e.g., memory and executive control functions).
• The effects of physical activity on brain health across the lifespan with a specific focus on brain aging.

collaborators: Gene Alexander, Andrea Giuffrida, Gregory Gerdeman, John Polk, Adam Gordon

 

Energetics and Physical Activity in Human Hunter-gatherers and Nonhuman Primates

Energy use is a main target of natural selection and our lab is involved in several projects examining energy use strategies in humans and nonhuman primates. These projects are all aimed at understanding how energy budgets impact human and nonhuman primate evolution. Many of these projects involve field studies of total daily energy budgets using the doubly-labeled water method. We also use accelerometry and other objective methods to measure physical activity levels. Recent projects include:

 

• Total energy expenditures in human hunter-gatherers
• Physical activity and inactivity in human hunter-gatherers assessed with objective methods (accelerometers, heart-rate monitors, gps, etc.)
• Total energy expenditures in great apes
• The effects of energy budgets on abundance patterns and life history in humans and nonhuman primates

 

collaborators: Herman Pontzer, Brian Wood, Marc Hamilton, Ted Zderic