Temperature affects everything that an organism does. Although we have an increasingly sophisticated understanding of evolutionary adaptation to temperature at the molecular level for some cellular processes, we still know little about evolutionary temperature adaptation in gene expression, cell-cycle control or growth, all of which influence organism performance and fitness. Recent studies have shown that the physiological costs of evolutionary temperature adaptation vary with body temperature. Here, I argue that this macroecological pattern has powerful consequences for life-history theory, and probably also for food-web dynamics, biological diversity and biotic response to climate change. The relationships among evolution, temperature and ecology are multivariate, hierarchical and complex making evolutionary physiology at the macroecological scale an exciting and challenging agenda for the next decade.