The gatekeeper function of histones in cellular memory. The dauer state of C. elegans induces global changes in histone marks that are necessary, but not sufficient, for the formation of a cellular memory that governs life history traits. The dauer-dependent histone signature serves as a kind of rudimentary memory that prepares the ground for further downstream site-specific changes in gene transcription, which lead to a consolidation of the memory process. The epigenetic mechanisms that read the dauer signature, rewrite local histone marks and control transcriptional factors that together induce local changes in gene expression are currently unknown. Ultimately, these transcriptional events trigger altered developmental trajectories that underpin life history traits and manifest with distinct phenotypes.