Why ontogeny recapitulates phylogeny

We have evolved by retaining the juvenile characters of our ancestors and have achieved both behavioral flexibility and our characteristic morphology thereby large brains by prolonged retention of rapid fetal growth rates, for example.

As biologists, we deal directly with the kind of material complexity that confers an unbounded potential upon simple, continuous changes in underlying processes. This is the chief joy of our science. Celebrating University Press Week. Email Facebook Twitter. Learning about phylogeny from ontogeny By studying ontogeny the development of embryos , scientists can learn about the evolutionary history of organisms.

Not recapitulation In the late s some scientists felt that ontogeny not only could reveal something about evolutionary history, but that it also preserved a step-by-step record of that history. Teach your students about development: Mealworm metamorphosis , a classroom activity for grades From butterflies to humans , a lecture for grades Footer Connect Email Facebook Twitter.

This conception was part of Darwin's account of ontogeny in The Origin of Species. Although von Baer's theory was overshadowed by recapitulation theory for most of the nineteenth century, scientists in the twentieth century began to adopt von Baer's view as the more accurate representation of development.

Haeckel's biogenetic law was further discredited by the results of experimental embryologists in the early twentieth century. Researchers abandoned Haeckel's theory when they couldn't confirm his observations. Embryologists showed that cases of recapitulation were less prevalent than were the inconsistencies between the developmental stages of normal organisms from different species.

Elizabeth Barnes. Keywords: biogenetic law , recapitulation. Ernst Haeckel 's Biogenetic Law The biogenetic law is a theory of development and evolution proposed by Ernst Haeckel in Germany in the s. Sources von Baer, Karl Ernst. Beobachtung und reflexion [ On the Developmental History of the Animals. Observations and Reflections ]. Cope, Edward. New York: D. Appleton and Co. Darwin, Charles R. London: John Murray Publishing House, Gould, Stephen J.

Ontogeny and Phylogeny. Cambridge: Harvard University Press , The Structure of Evolutionary Theory. Haeckel, Ernst. Generelle morphologie der organismen [ General Morphology of the Organisms ]. Berlin: G. Reimer, Actually, it is the namesake of recapitulation theory. Recapitulation theory posits that the development of individual organisms ontogeny follows recapitulates the same phases of the evolution of larger ancestral groups of related organisms phylogeny.

Applying this theory loosely, a seedling of a recently speciated flowering plant something that recently evolved to be a species would, throughout its embryological development, mimic the morphology of more ancestral plants—or plants that evolved in earlier times.

In theory, then, a young flowering plant might go through developmental stages that look like a moss or early land plant , then a fern or other vascular plants , then a gymnosperm or other seed plants , and so on. Of course, this is not really true, but the implication is that there may be embryological similarities.