As somatic mutations are reliably inherited by daughter cells, they can be used to retrace lineages of cells and reconstruct phylogenies, reflecting early development, tissue renewal and age-related aberrances. While the vast majority of somatic mutations do not alter the phenotypes of cells, some mutations affect key genes that grant cells a selective advantage and lead to expansions of these lineages. Over time, our tissues become patchworks of mutant clones. These clonal expansions, especially clonal hematopoiesis, have been associated with diverse disease risks, such as cancers, cardiovascular disease and neurodegenerative disorders. In this session, we will hear about efforts to trace the lineages of cells and quantify somatic evolution.