In this episode of BoneTalk, host Barbara Hannah Grufferman is joined by Dr. Daniel Lieberman, author of “Exercised: Why Something We Never Evolved to Do is Healthy and Rewarding.” Dr. Lieberman, professor of human evolutionary biology at Harvard University and a pioneering researcher on the evolution of human physical activity, tells the story of how humans never evolved to exercise – to do voluntary physical activity just for the sake of better health. Yet due to modern innovations and lifestyle changes, we must now choose to exert energy for the sake of our health.