Abstract

In my field, animal developmental biology, and in what could be regarded as its “deep time derivative,” the evolutionary biology of the animal body plan, there exist two kinds of experimentally supported causal explanation. These can be described as “rooted” and “unrooted.” Rooted causal explanation provides logical links to and from the genomic regulatory code, extending right into the genomic sequences that control regulatory gene expression. The genomic regulatory code ultimately determines the developmental process in a direct way, since subsequent developmental events all depend directly and specifically on what regulatory genes are being expressed and where in the developing organism they are being expressed..