HIGHLIGHTS
• Open-access life history data have proliferated dramatically in recent years and macro-ecological studies are using these data to examine patterns in life histories across the tree of life.
• These studies support the fast-slow continuum being the dominant – but not unique – axis structuring life history variation: other important axes associated with development, reproductive tactics, and demographic buffering have emerged.
• Here, we make recommendations for characterising life history through data choices and analytical methods of dimensionality reduction, with recourse to a clear model of life history.
• We use our framework to advocate that future empirical studies of life history evolution take hypothesis-driven approaches that investigate classical and emerging life history theories, to reveal novel axes, clusters, and boundaries of life history variation across all taxa.