Editing Neural Darwinism (section)

==== Primary repertoire- developmental selection ====

The first tenet of TNGS concerns events that are embryonic and run up to the neonatal period. This part of the theory attempts to account for the unique anatomical diversification of the brain even between genetically identical individuals. The first tenet proposes the development of a primary repertoire of degenerate neuronal groups with diverse anatomical connections are established via the historical contingencies of the primary processes of development. It seeks to provide an explanation of how the diversity of neuronal group [[phenotypes]] emerge from the organism's [[genotype]] via [[Genetics|genetic]] and [[Epigenesis (biology)|epigenetic]] influences that manifest themselves mechano-chemically at the cell surface and determine connectivity.

Edelman list the following as vital to the formation of the primary repertoire of neuronal groups but, also contributing to their anatomical diversification and variation:

* Cell division – there are repeated rounds of cell division in the formation of neuronal populations
* Cell death – there is extensive amounts of pre-programmed cell death that occurs via apoptosis within the neuronal populations.
* Process extension and elimination – the exploratory probing of the embryonic environment by developing neurons involve process extension and elimination as the neurons detect molecular gradients on neighboring cell surface membranes and the substrate of the extracellular matrix.
* CAM & SAM action – the mechanochemistry of cell and surface adhesion molecules plays a key role in the migration and connectivity of neurons as they form neuronal groups within the overall distributed population.

Two key questions with respect to this issue that Edelman is seeking to answer "in terms of developmental genetic and epigenetic events" are:{{sfn|Edelman|1987b|p=75}}

* "How does a one-dimensional genetic code specify a three-dimensional animal?"
* "How is the answer to this question consistent with the possibility of relatively rapid morphological change in relatively short periods of evolutionary time?"