Nature: Pittis A, Gabladon T.

The eukaryote cell is so much larger and more complex than the cells of bacteria and archaea that it is hard to recreate the steps whereby it evolved. One current view is that the evolution of eukaryotes was triggered when an archaea-like cell accommodated the bacteria that went on to become mitochondria. An alternative view is that eukaryotes were well on the way to their modern form before they acquired the bacteria that became mitochondria. This second view is supported by a study by Alexandros Pittis and Toni Gabaldón 57954; showing that mitochondrial genes are more closely similar to those of their supposed bacterial relations than many other eukaryote genes are to their own inferred prokaryote cousins. This result, which challenges current views, suggests that mitochondria were late additions to a eukaryote cell that was already evolving.