And these nucleated cells, the eukaryotes then existed in single-cell form for perhaps the next 700 or 800 million years until multi-cellular aggregates of eukaryotic cells first assembled to become the ancestors of the multi-cellular plants and the multi-cellular animals that exist on
the surface of the Earth today. To put that in perspective, our species has only been on the planet for about 150,000 years. So we’ve all been here for that period of time.