It was a great pleasure to welcome Jean-François Lemaître to Bielefeld as the guest speaker in our Behaviour & Evolution Seminar Series this week, in which he talked about “Understanding sex-differences in ageing: insights from natural populations of mammals”. Jean-François is a CNRS researcher based at the Laboratoire de Biométrie et Biologie Évolutive in Lyon, where he works on the evolutionary demography of wild mammals. Thanks for your visit, Jeff!