Creation of the Eighteenth Men

The Creation of the Eighteenth Men is the last species-making turn in the book’s long history of humanity remaking itself. The Seventeenth Men, dissatisfied with subtle imperfections they could not themselves understand, devoted their strength to producing a successor intended to be like them but perfected. That successor, the Eighteenth Men, became the final human species, and the history of earlier cultures gives way to their world.

From Successor to Successor

The creation follows a chain of deliberate redesign. After a hundred million years, the Sixteenth Men produced a new human type they believed fulfilled their deepest hopes. That type became the Seventeenth Men. Once they had spread across the world and reached full cultural stature, however, they too turned toward making a successor. The sequence makes creation both an inheritance and a judgment: each species receives the power to shape its future, but its confidence in the result does not ensure that its own unresolved problems have been overcome.

The Seventeenth Men’s Imperfection

The Seventeenth Men’s makers had believed they had achieved their heart’s desire, yet the new beings were afflicted by subtle imperfections beyond their creators’ comprehension. The account does not identify those defects or describe the methods used to correct them. It does establish the motive for the next act of creation: the Seventeenth Men set out to produce a type essentially like themselves, but perfected. Their project thus repeats the aspiration of their predecessors while arising from a failure those predecessors could not foresee.

The Replacement and Its Scale

The Seventeenth Men’s career lasted only a few hundred thousand years, though it was crowded with splendour and agony. They gave way to the Eighteenth Men as the new species peopled the world. The transition is presented not as an isolated invention but as a species-level succession: one human form undertakes its own replacement, and the resulting kind becomes the endpoint of the book’s account of human species. The Eighteenth Men are explicitly identified as the last human species; the narrative consequently passes over the earlier cultures of the Seventeenth Men and turns to the age of the Last Men.

A Recurring Human Experiment

This final creation belongs to a much older pattern in which human physical nature is repeatedly transformed, and in which biological change carries risks as well as promise. The First Men lost their unusual capacity for prolonged youth under the pressures of an unnatural environment. Among the Second Men, brain growth threatened the body’s ability to sustain it, producing widespread mental impairment before a healthier inherited variety saved the species. The Third Men’s repeated efforts to remake human nature also included a civilization that collapsed after the misguided breeding of specialized workers. These episodes do not explain the Seventeenth Men’s particular defects, which remain unspecified, but they frame the creation of their successor as the latest attempt to escape the limitations of an existing human type. Its decisive historical consequence is clear: the attempt establishes the Eighteenth Men as humanity’s final species.