Abstract
The prokaryote/eukaryote dichotomy is the biggest divide of all life forms that still remains largely unexplained by evolutionary biologists. The phylogenetic relationship of eukaryotes to the prokaryotic group of Archaea suggests that eukaryotes arose from that taxonomic domain. However, the widespread association of eukaryotic metabolic proteins with eubacterial homologs complicates the simple explanation of an archaeal-to-eukaryotic evolutionary transition. Models favoring ‘phagocytosis-first’ or ‘mitochondria-first’ scenarios posit that the early appearance of these cell biological traits were ‘triggers’ for the development of the eukaryotic cell from a prokaryotic progenitor. However, these models fail to fully account for the origin of eukaryote cell complexity. In addition, recent research points to the notion that all eukaryotic traits appear to have emerged concomitantly and were present in the last eukaryotic common ancestor (LECA). New models are therefore required to provide a more comprehensive explanation for the evolution of the eukaryotes.