One of the most significant events in the evolution of life is the origin of the eukaryotic cell, an increase in cellular complexity that occurred approximately 2 billion years ago. Ground-breaking research has centered around unraveling the characteristics of the Last Eukaryotic Common Ancestor (LECA) and the nuanced archaeal and bacterial contributions in eukaryogenesis, resulting in fundamental changes in our understanding of the Tree of Life. The archaeal and bacterial roles are covered by theories of endosymbiogenesis wherein an ancestral host archaeon and a bacterial endosymbiont merged to create a new complex cell type – Eukarya – and its mitochondrion. Eukarya is often regarded as a unique and distinct domain due to complex innovations not found in archaea or bacteria, despite housing a chimeric genome containing genes of both archaeal and bacterial origin. However, the discovery of complex cell machineries in recently described Asgard archaeal lineages, and the growing support for diverse bacterial gene transfers prior to and during the time of LECA, is redefining our understanding of eukaryogenesis. Indeed, the uniqueness of Eukarya, as a domain, is challenged. It is likely that many microbial syntrophies, encompassing a ‘microbial village’, were required to ‘raise’ a eukaryote during the process of eukaryogenesis.

生命进化中最重要的事件之一是真核细胞的起源，即大约 20 亿年前发生的细胞复杂性的增加。开创性的研究集中在揭示最后的真核生物共同祖先 (LECA) 的特征以及真核发生中古细菌和细菌的细微贡献，从而使我们对生命之树的理解发生根本性变化。内共生理论涵盖了古细菌和细菌的作用，其中一个祖先宿主古细菌和一种细菌内共生体合并形成一种新的复杂细胞类型——真核细胞——及其线粒体。由于古生菌或细菌中没有发现的复杂创新，真核生物通常被认为是一个独特而独特的领域，尽管它拥有一个包含古生菌和细菌起源基因的嵌合基因组。然而，在最近描述的 Asgard 古细菌谱系中发现了复杂的细胞机制，以及在 LECA 之前和期间对多种细菌基因转移的日益支持，正在重新定义我们对真核发生的理解。事实上，真核生物作为一个领域的独特性受到了挑战。在真核发生过程中，可能需要许多包含“微生物村”的微生物共生体来“培养”真核生物。