Ontogeny Recapitulates Phylogeny, Part Two: Problems and Influences

If Haeckel's model, as described in Part One, were literally true, it would make the study of phylogeny into a straightforward interpretation of embryology. However, Haeckel's version of "ontogeny recapitulates phylogeny" is false in many aspects. Considering the example of the human embryo, there is no stage at which it has functional gills used for breathing. In fact, a human embryo never breathes, since it receives all the oxygen it requires through the placenta. The structures that resembled gills to Haeckel are called pharyngeal arches, and in humans they are precursors of structures of the head and neck such as the ears, jaw, and larynx. In fact, at no stage does a human embryo resemble an adult fish, reptile, or primitive mammal in any but the most superficial way.

Haeckel's model, like the Lamarckism that underlies it, proposes no underlying mechanism. Though evolutionary changes take place through use or disuse of organs, no reason is given why that should be so. One could just as reasonably assume that using an organ might diminish it rather than enlarge it. In fact, both phenomena can be observed in life; using a muscle causes its size to increase, but using teeth causes them to wear down.

Lamarckism fails as a theory not only in evolution, but in ontology as well. An embryo does not use many structures for their intended adult functions before these functions develop. A human embryo does not have to try to use its arm buds to manipulate objects to cause hands and fingers to develop, nor does it have to strive to see in the dark interior of the womb to cause its eyes to develop.

Granville Stanley Hall, founder of the American Psychological Association, was an educator, psychologist, and pioneer in the field of child development. His ideas were heavily influenced by his belief that ontogeny recapitulates phylogeny, and he applied the idea to stages of child development. His belief was that each developmental stage reflected a stage in the "phylogeny" of a person's civilization. Personality and human behavior, according to this view, are inherited from the cultural rules of one's ancestors, and a child passes through these stages during development.

In Hall's view, early childhood is a time of "savagery" reflecting pre-civilization. Reason and morals are only slightly developed in middle childhood, and Hall believed children were better off engaging in "tribal" activities like fishing and roaming the country rather than reading and studying, reflecting the behavior of their ancestors from tribal cultures. These ideas seem to be a peculiar corollary from Haeckel's idea that ontogeny recapitulates phylogeny, based on the simple observation that an embryo has a superficial resemblance to a fish.

Though no longer accepted in its original form, and though ideas derived from it are no longer predominant in the social sciences, the concept of recapitulation still retains some value. Part Three of this series will explain what "ontogeny recapitulates phylogeny" means in modern zoology.