Prompt 1F ("Genetics & the Development of the Nervous System" Lecture(s)): Many neurons in the developing nervous system are pre-programmed to undergo apoptosis within a certain time window. In other words, unless they receive neurotrophic factors from their postsynaptic targets, they cooperatively destroy themselves. This means that cells must ‘fight’ to survive – and can only do so by remaining active. Why do you think the nervous system is set up this way? Using related concepts and terminology, make an argument why this strategy is more efficient than one that ensures the survival of ALL cells.