Whether identified as “genies,” “little men,” or simply “les moi,” a vast horde of personified mental faculties populates In Search of Lost Time, responsible for behaviors too instantaneous or too ingrained to come under conscious control. Representing automatic neural subroutines as self-interested beings allows Proust to apply the principles of biological selection to these psychological entities, imagining the mind as an ecosystem in which great personal upheavals—for instance, Marcel's loss of Albertine—figure as extinction events that wipe out large populations of narrowly specialized, slow-to-adapt “genies.” Since genies are optimized for highly specific micro-environments, the same “species” of genie may form in any two individuals who share such a micro-environment, with this indifference to the boundaries of the person making it possible for a shared genie-type to define an ad hoc social category: homosexuals, snobs, members of the Guermantes set. In this essay, I unpack Search's model of the mind as a population of simple homunculi and explore its effect on Proust's understanding of interpersonal collectives, from intellectual coteries to social classes. The construct of the genie, I suggest, not only allows Proust to suture together sub-individual and supra-individual scales of analysis but also enables a model of change—both psychological and historical—that is neither simply agentic nor simply deterministic. Rather, the shifting demographics of mental homunculi constitute a quantitative, probabilistic, and nonsychronous form of change, creating new adaptive niches while permitting the partial survival of prior forms of life.