Intermediary metabolism and the biochemical-molecular basis of life history variation and trade-offs in two insect models / Anthony J. Zera and Lawrence G. Harshman -- Epistatic social and endocrine networks and the evolution of life history trade-offs and plasticity / Lesley T. Lancaster and Barry Sinervo -- Hormonally-regulated trade-offs: evolutionary variability and phenotypic plasticity in testosterone signaling pathways / Michaela Hau and John C. Wingfield -- Does impressive progress on understanding mechanisms advance life history theory? / Stephen C. Stearns -- What mechanistic insights can or cannot contribute to life history evolution - an exchange between Stearns, Heyland, and Flatt / Thomas Flatt, Andreas Heyland, and Stephen C. Stearns.