108 with male–female dichotomy were probably also achieved relatively easily in evolution. In the ﬁrst phase of the sexual life cycle of V. carteri females, only the ﬁrst asymmetrical cell division had to be postponed from the sixth to the seventh division cycle. The large reproductive cell initials develop into haploid eggs, which resemble haploid gonidia, albeit somewhat smaller; in fact, after a waiting period, unfertilized eggs can develop into gonidia and enter the asexual cycle. Likewise, in the ﬁrst phase of the sexual life cycle of V. carteri males, only the asymmetrical cell division had to be postponed from the sixth to the eighth division cycle. However, these large reproductive cell ini- tials later undergo six additional symmetric division cycles to form small haploid biﬂagellate sperm cells. Such traits and cleavage programs related to fertilization and repro- duction are known to evolve extremely rapidly (Rice 1998; Palumbi 1998; Howard et al. 1998; Gavrilets 2000). After fertilization, the formation of dormant, heavily walled, diploid zygotes/zygospores in multicellular species is quite similar to that observed in unicellular species. Taken together, the evolution of multicellularity, development of sterile somatic cells, and generation of a male–female dichotomy are clearly among life’s greatest innovations. However, we learn from volvocine algae that the transition to such complex life is probably much easier to achieve than might be commonly believed. Volvox and its relatives seem to be ideal model organisms for addressing fundamental issues in the evolution of organ- ismic complexity and for discovering universal rules that characterize this transition. The post-genomic era is just beginning for Chlamydo- monas and Volvox. 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