Developmental biologist proposes new theory of early animal evolution, challenges basic assumptions [View all]

[Jim__]

From Phys.org:

A New York Medical College developmental biologist whose life's work has supported the theory of evolution has developed a concept that dramatically alters one of its basic assumptions—that survival is based on a change's functional advantage if it is to persist. Stuart A. Newman, Ph.D., professor of cell biology and anatomy, offers an alternative model in proposing that the origination of the structural motifs of animal form were actually predictable and relatively sudden, with abrupt morphological transformations favored during the early period of animal evolution.

Newman's long view of evolution is fully explained in his perspective article, "Physico-Genetic Determinants in the Evolution of Development," which is to be published in the October 12 issue of the journal Science, in a special section called Forces in Development. The paper has been selected for early online publication and a podcast interview with the scientist.

Evolution is commonly thought to take place opportunistically, by small steps, with each change persisting, or not, based on its functional advantage. Newman's alternative model is based on recent inferences about the genetics of the single-celled ancestors of the animals and, more surprisingly, the physics of "middle-scale" materials.

Animal bodies and the embryos that generate them exhibit an assortment of recurrent "morphological motifs" which, on the evidence of the fossil record, first appeared more than a half billion years ago. During embryonic development of present-day animals, cells arrange themselves into tissues having non-mixing layers and interior cavities. Embryos contain patterned arrangements of cell types with which they may form segments, exoskeletons and blood vessels. Developing bodies go on to fold, elongate, and extend appendages, and in some species, generate endoskeletons with repeating elements (e.g., the human hand).

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