Research from Oxford University published today in the journal Genome Research has found that a special combination of epigenetic modifications crucial to stem cell growth evolved in animals much earlier than previously appreciated. These findings imply that human stem cells, and those of simple animals such as planarian worms, have much more in common at the epigenetic level than previously thought. These insights could enhance the use of stem cells in regenerative medicine-based approaches to treating tissues and organs damaged by disease or age.