The paper by T. Cavalier-Smith revisits the theory of the origin of eukaryotes from a phagotrophic ancestor, emphasizing the role of phagotrophy in the evolution of key eukaryotic traits such as the endomembrane system, cytoskeleton, nucleus, mitosis, and sex. Cavalier-Smith argues that these innovations partially overlapped and were synergistic with the symbiogenetic origin of mitochondria from an α-proteobacterium. The ancestral eukaryote is described as a uniciliate with a single centriole and a simple centrosomal cone of microtubules, similar to the zooflagellate *Phalansterium*. The root of the eukaryote tree is placed between opisthokonts (animals, Choanozoa, fungi) and all other eukaryotes, designated as 'anterokonts' due to the ancestral presence of an anterior cilium. Cavalier-Smith discusses the relationship between 13 protozoan phyla and revises higher protozoan classification, placing the secondarily amitochondrial Archezoa within a new infrakingdom Excavata. He also groups infrakingdoms Excavata and Alveolata together as subkingdom Corticata and establishes a new subkingdom Gymnomyxa to embrace the majority of the former sarcodine protozoa. The paper highlights the importance of membranes and the cell skeleton in providing the environment for genome evolution and the co-evolution of these structures. Cavalier-Smith concludes that the origin of eukaryotes and the symbiogenetic origin of mitochondria likely occurred around 850 million years ago, much more recently than previously thought.The paper by T. Cavalier-Smith revisits the theory of the origin of eukaryotes from a phagotrophic ancestor, emphasizing the role of phagotrophy in the evolution of key eukaryotic traits such as the endomembrane system, cytoskeleton, nucleus, mitosis, and sex. Cavalier-Smith argues that these innovations partially overlapped and were synergistic with the symbiogenetic origin of mitochondria from an α-proteobacterium. The ancestral eukaryote is described as a uniciliate with a single centriole and a simple centrosomal cone of microtubules, similar to the zooflagellate *Phalansterium*. The root of the eukaryote tree is placed between opisthokonts (animals, Choanozoa, fungi) and all other eukaryotes, designated as 'anterokonts' due to the ancestral presence of an anterior cilium. Cavalier-Smith discusses the relationship between 13 protozoan phyla and revises higher protozoan classification, placing the secondarily amitochondrial Archezoa within a new infrakingdom Excavata. He also groups infrakingdoms Excavata and Alveolata together as subkingdom Corticata and establishes a new subkingdom Gymnomyxa to embrace the majority of the former sarcodine protozoa. The paper highlights the importance of membranes and the cell skeleton in providing the environment for genome evolution and the co-evolution of these structures. Cavalier-Smith concludes that the origin of eukaryotes and the symbiogenetic origin of mitochondria likely occurred around 850 million years ago, much more recently than previously thought.