Long-lived species maintain epigenome stability through enhanced DNMT1 fidelity and SIRT6 chromatin silencing

Bowhead whales and Greenland sharks keep their DNA methylation patterns stable for centuries—not by preventing errors, but by correcting them faster than they accumulate. The mechanism: DNMT1 proofreading and SIRT6 deacetylation work together to maintain heterochromatin boundaries.