During the long period of postnatal development in humans, the cerebral cortex undergoes intense synaptogenesis, which persists into adulthood. The steady interaction with the physical, social, and cultural environment drives an epigenetic selection of neuronal networks to internalize, in particular, the common cultural and ethical rules of the society to which the child and her/his family belong. Based on this knowledge, we propose the idea of proactive epigenesis to develop new ethical rules and educational approaches to influence, and constructively interact with the developing neuronal architecture of the human brain.
Conrad Waddington used the word epigenesis to describe how genes interact with their environment to produce a phenotype; in other words, how the inherited potential of the genome develops into an adult organism . This definition was applied by Changeux et al to the developing brain, assuming that, throughout a sequence of nested developmental stages, the environment leaves characteristic “prints” in the connective organization of the child's brain . At each of these elementary steps, the synaptic network in the brain first becomes transiently larger and less specified than in the adult; the activity of the network—spontaneous or evoked by the outside world—then regulates the stabilization and degeneration (pruning) of labile synapses.
This theory was an attempt to explain the paradox of nonlinear evolution of brain‐vs.‐genome complexity. From the mouse (75 million neurons, with about 100 billion synapses) to the human brain (85 billion neurons, with a million billion synapses), the complexity and organization of the brain have dramatically increased, whereas the number of coding genes in the genome has remained almost constant at 20,000–25,000 structural genes in mouse, monkey, and human and the sequence differences in these genes are rather small. Moreover, the postnatal period of brain maturation is much longer in humans than in …