[H]istorical science is not worse, more restricted, or less capable of achieving firm conclusions because experiment, prediction, and subsumption und… - Stephen Jay Gould

We do not inhabit a perfected world where natural selection ruthlessly scrutinizes all organic structures and then molds them for optimal utility. Organisms inherit a body form and a style of embryonic development; these impose constraints upon future change and adaptation. In many cases, evolutionary pathways reflect inherited patterns more than current environmental demands. These inheritances constrain, but they also provide opportunity. A potentially minor genetic change […] entails a host of complex, nonadaptive consequences. The primary flexibility of evolution may arise from nonadaptive by-products that occasionally permit organisms to strike out in new and unpredictable directions. What “play” would evolution have if each structure were built for a restricted purpose and could be used for nothing else? How could humans learn to write if our brain had not evolved for hunting, social cohesion, or whatever, and could not transcend the adaptive boundaries of its original purpose?

[W]hat intellectual phenomenon can be older, or more oft repeated, than the story of a large research program that impaled itself upon a false central assumption accepted by all practitioners? Do we regard all people who worked within such traditions as dishonorable fools? What of the scientists who assumed that the continents were stable, that the hereditary material was protein, or that all other galaxies lay within the Milky Way? These false and abandoned efforts were pursued with passion by brilliant and honorable scientists. How many current efforts, now commanding millions of research dollars and the full attention of many of our best scientists, will later be exposed as full failures based on false premises?

This essay treats the most celebrated story in the extreme simplification in an adult parasite - in the interests of illuminating, reconciling, and, perhaps, even resolving two major biases that have so hindered our understanding of natural history: the misequation of evolution with progress, and the undervaluing of an organism by considering only its adult form and not the entire life cycle.