ABSTRACT
This paper considers the origins of differences among children, and within a child from time to time, in the early development of speech. The paper is biased toward viewing these differences as special cases of general variability in animal behavior and its development. Some variability among children is surely genetic in origin (Lieberman, Chapter 4); this is the stuff of natural selection. Other variability is precisely what we expect in a system growing from an open genetic program (Mayr, 1974), that depends on loosely invariant properties of the environment to specify the course of development (for elaboration, see below, and for an excellent brief discussion, see Lenneberg, 1967, Ch.1). Finally, variability within a child is a precondition of the adaptive biological process that we term "learning" (Fowler & Turvey, 1978). However, I will come to all these matters only in the last section of the paper.
