Milestones in understanding clonal hematopoiesis and preventing complications. The Elfstedentocht is an iconic 200-km ice-skating marathon along the canals, lakes, and rivers linking 11 cities in Friesland, the northernmost province in The Netherlands. Along with the neighboring province of Groningen, Friesland contributed most of the patients to the LifeLines population cohort and to the new study by van Zeveneter and colleagues, in which somatic mutations were found to be slightly more common in anemic elderly people compared to nonanemic controls, but common in both groups. The Elfstedentocht can only take place in the heart of winter after a long period of cold weather, when ice thickness reaches ≥15 cm along the along the entire skating route. Perhaps due to global warming, the event has not been held since 1997, and an “alternative” route has been substituted in colder Austria. Before 1960 and discovery of the Philadelphia chromosome, the genetic basis of hematological neoplasia was not understood. In the 1990s, molecular biology techniques permitted the observation that the same genetic variants associated with neoplasms, such as chronic myeloid leukemia, are sometimes present in blood cells in healthy people, albeit transiently, while the high prevalence and stability of certain types of expanded hematopoietic clones were definitively demonstrated in large-cohort and population-based studies of somatic mosaicism from 2012 onward. The next historical “milestones” along this lengthy journey of discovery and translation will include development of methods to eliminate dangerous mutant clones and prevent their complications, including cytopenias, inflammatory complications, and clonal progression. CH, clonal hematopoiesis; HN, hematological neoplasms; HSC, hematopoietic stem cells.