Emergence of Eukaryotic Cells

Between 1.8 and 1.6 billion years ago, the first eukaryotic cells emerged. Evidence comes from microfossils, molecular biomarkers, and phylogenetic analyses. These cells contained membrane-bound nuclei and specialized organelles including mitochondria. Evidence suggests eukaryotes evolved through endosymbiosis, where larger cells engulfed and incorporated free-living prokaryotes. The fossil record shows larger, more complex cells appearing in this period, notably in the Gunflint Formation and Roper Group. While these early eukaryotes remained unicellular, this cellular development preceded all complex multicellular life, including plants, fungi, and animals.