The emergence of eukaryotic cells is considered as a critical biological evolutionary event on Earth. The origin of eukaryotes and eukaryosis are frontier issues in both life and Earth sciences. Currently, it is widely accepted that the origin of eukaryotes was initiated with a symbiotic process, in which one endosymbiotic host cell became the cell nucleus and one endosymbiotic alphaproteobacterium evolved into a mitochondrion.
Click here for original story, Njordarchaeota, a new candidate for a sister group to eukaryotes
Source: Phys.org