In children and young adults, for example, histone H3 is closely associated with various cancers. While histone H3 is particularly abundant in multicellular organisms such as plants and animals, unicellular organisms teem with a nearly identical variant of H3. That's why scientists think the difference in rations of H3 and its variant hold crucial clues in the mystery of why pluripotent cells are so versatile during early development. The researchers revealed that as C. elegans roundworm embryos grew, increasing H3 levels in their systems restricted the potential or "plasticity" of their pluripotent cells. In pluripotent cells, histones help switch certain genes on and off to commit to specific cell types, be they neurons, muscles, or other tissue.