other capacities but stress the specifically linguistic parts, whereas the reverse is true of non-linguists. The discussion
here has, I hope, clarified the sorts of evidence one might adduce.
Allaspectsoftheinitialstate,specializedand general, areinturngovernedbya combinationofgeneticprespecification
and principles of brain development. The latter may well depend on certain sorts of inputs being available as triggers.
The balance between these factors is far beyond the everyday concerns of linguists, though in the end it must play a
role. All aspects of the initial state are also outcomes of an evolutionary process that relates humans to the other
species of the world.
We have thus traced a chain of relationships among a diverse set of research programs, from observations about
particular languages and how parentstalk totheirchildrenallthewaytogeneticsand evolutionary theory. As observed
at the outset of this chapter, what brings these diverse enterprises into contact is precisely the hypothesis of Universal
Grammar.