Penny's research focuses on the evolution of social emotions and the significance of care for the vulnerable in human origins.
Penny's latest book, 'Hidden Depths: The origins of human connection' (White Rose University Press, open access) builds on her previous volume 'How Compassion Made Us Human' (Pen and Sword) in arguing that a selection for pro-social emotional motivations has been the driving force behind human evolution. She particularly explores how at each stage in our evolutionary past changes which led to human success came alongside new sensitivities and vulnerabilities. and how this understanding changes our view of ourselves.