Phagocytosis, or ‘cell eating’, is a eukaryote-specific process where particulate matter is engulfed via invaginations of the plasma membrane. The origin of phagocytosis has been central to discussions on eukaryogenesis for decades­, where it is argued as being either a prerequisite for, or consequence of, the acquisition of the ancestral mitochondrion. Recently, genomic and cytological evidence has increasingly supported the view that the pre-mitochondrial host cell—a bona fide archaeon branching within the ‘Asgard’ archaea—was incapable of phagocytosis and used alternative mechanisms to incorporate the alphaproteobacterial ancestor of mitochondria. Indeed, the diversity and variability of proteins associated with phagosomes across the eukaryotic tree suggest that phagocytosis, as seen in a variety of extant eukaryotes, may have evolved independently several times within the eukaryotic crown-group. Since phagocytosis is critical to the functioning of modern marine food webs (without it, there would be no microbial loop or animal life), multiple late origins of phagocytosis could help explain why many of the ecological and evolutionary innovations of the Neoproterozoic Era (e.g. the advent of eukaryotic biomineralization, the ‘Rise of Algae’ and the origin of animals) happened when they did.

吞噬作用或“细胞吞噬”是真核生物特有的过程，其中颗粒物质通过质膜内陷被吞噬。几十年来，吞噬作用的起源一直是真核发生讨论的核心，人们认为吞噬作用是获得祖先线粒体的先决条件或结果。最近，基因组和细胞学证据越来越多地支持这样的观点，即前线粒体宿主细胞——“阿斯加德”古细菌中分支的真正古细菌——无法吞噬作用，并使用替代机制来整合线粒体的α变形菌祖先。事实上，真核树上与吞噬体相关的蛋白质的多样性和变异性表明，如在各种现存真核生物中所见，吞噬作用可能在真核树冠群中独立进化了几次。由于吞噬作用对于现代海洋食物网的功能至关重要（没有它，就不会有微生物循环或动物生命），吞噬作用的多个晚期起源可以帮助解释为什么新元古代的许多生态和进化创新（例如真核生物矿化的出现、“藻类的兴起”和动物的起源）就在他们这样做的时候发生了。