The system of gene regulation that controls animal-body-plan development is exquisitely integrated, so that significant alterations in these gene regulatory networks inevitably damage or destroy the developing animal.32 But given this, how could a new animal body plan, and the new dGRNs necessary to produce it, ever evolve gradually via mutation and selection from a preexisting body plan and set of dGRNs? Davidson makes clear that no one really knows: “contrary to classical evolution theory, the processes that drive the small changes observed as species diverge cannot be taken as models for
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