A majority of the human genome consists elements called transposable elements – the fossils of evolutionary battles between ancient viruses and their human hosts. The human genome silences these elements by creating a specialized structure called heterochromatin on top of them. Dr. Keith Maggert and graduate student Farah Bughio's study in PNAS shows that heterochromatin is not as stable and reliable a protector as was previously thought, and instead turns on and off randomly and repeatedly throughout life, allowing transposable elements the freedom to once again move around the genome and cause damage. More information can be found here: PMID 31527269
