The new study, published in Nature, was led by researchers from the Wellcome Sanger Institute, in collaboration with the TwinsUK study at King’s College London. The researchers introduced an improved version of nanorate sequencing (NanoSeq)—an ultra-accurate DNA sequencing technique.

By applying targeted NanoSeq to cheek swabs and blood samples from more than 1,000 volunteers, the team uncovered a rich landscape of mutations in healthy tissues, giving the most detailed picture so far of how tissues mutate over time.

As people age, their cells naturally acquire DNA mutations which are known as somatic mutations. Most are harmless, but some can provide a growth advantage, leading to “clones” of cells that carry the same mutations. As they multiply, some patches of clones have the potential to become the earliest stage in cancer development, but they may also contribute to aging and other diseases.