The waltzing kludge of eukaryotic life

At its heart, [the idea] is deceptively simple: we have two genomes that need to work together, and you can tell how well they’re doing this by the strength of the free radical leak. From that simple concept, you can logically derive how fitness, fertility and lifespan are linked in different species. You can also predict the process of ageing and the onset of age-related diseases within individuals. 

“A lot of this has to be true on logical grounds,” says Nick Lane. “We know that there is co-adaptation between these two genomes and many predictions emerge seamlessly from some simple reflections on that process. The big question is whether it’s important in the greater scheme of things.”

-- from The two-genome waltz: how the threat of mismatched partners shapes complex life by Ed Yong