Scientists from the University of Nottingham have now explained how the 'jumping genes' found in most living beings don't kill their hosts.
The study reveals for the first time how the movement and duplication of segments of DNA known as transposons, is regulated.
This prevents a genomic meltdown, and instead enables transposons to live in harmony with their hosts - including humans.
Transposons were discovered in the 1940s by Barbara McClintock, who was rewarded in 1983 with the Nobel Prize for Physiology or Medicine.
Ancient relics of these "jumping genes", as they are sometimes called, make up 50 percent of the DNA in humans.
They are characterised as "jumping" because they can change their position within the genome, thereby creating or reversing mutations.
This process, known as DNA transposition, plays a critical role in creating genetic diversity and enabling species to adapt and evolve.
The research appears in eLife, a prestigious new journal published jointly by The Wellcome Trust, The Howard Hughes Medical Institute and The Max Planck Institute.