The eukaryotic cell
One cell engulfs another and keeps it alive — and every plant, animal and fungus follows.
- When
- Known to
- ± 250 million years
- Era
- Paleoproterozoic, Proterozoic
An archaeal host takes in a bacterium that becomes the mitochondrion, producing a cell with an internal membrane system, a nucleus and vastly more available energy. Phylogenetics now places the mitochondrial acquisition close to the origin of the eukaryote lineage itself rather than long before it. Dating is imprecise — estimates span roughly 2.2 to 1.6 billion years — but the innovation is arguably the second most important in the history of life, after the origin of life itself.