Despite eons of mingling inside our cells, gene networks we’ve inherited from primitive, singled-celled ancestors have stayed separate. Our cells remain chimeras, a hybrid fusion of unrelated creatures.
The genes date from an event 1.5 billion years ago, when two kinds of simple cells, neither having a nucleus or cellular membrane, shacked up and created an entirely new form of life: eukaryotes.
While the two distinct communities of genes work together to keep cell machinery ticking, they otherwise stay out of each other’s hair, report biologists from the National University of Ireland.
“We humans, as part of the eukaryotes, we’re still a community of two prokaryotes,” said James McInerney, co-author of a study published in Genome Biology and Evolution, July 27.
While some scientists think prokaryotes evolved directly into eukaryotes, others think it required a merger, with two cells — one archaebacteria and one eubacteria — joining at some prehistoric point to make a cell capable of complex internal structures.