"The appearance of design in grammatical universals as evidence of
adaptation for non-communicative functions"

Huck Turner

University of Plymouth

huck.turner@plymouth.ac.uk

Many authors (e.g., Hauser, Chomsky & Fitch, 2002) have expressed doubts
that the evolution of grammatical universals can be exclusively
explained in terms of adaptation, noting that many such constraints have
a "tenuous connection to communicative efficacy" (p.1574), but even if
we assume that a given universal of grammar is unrelated to
communicative efficacy, this does not preclude it from being an
adaptation for non-communicative functions.  For instance, a universal
could be selected for improving language learnability or for its effects
on reducing the costs associated with the language faculty in terms of
metabolic energy or other neural resources.  The present study examines
one such hypothesis relating to closed-class functional categories
(i.e., grammatical words and inflections) and concludes that since they
appear to be extremely well designed to economise the lexicon, they are
probably worthy of being labelled an adaptation. 

	By encapsulating lexical categories, functional projections can
mediate grammatical relations so that lexical entries for lexical
categories can remain extremely simple in terms of formal features.  For
instance, learning that a noun is associated with determiners allows a
noun, encapsulated in a DP, to be used as either the subject or object
of a sentence or as the object of a preposition and so forth.  The
language learner does not have to learn all of the contexts in which a
new noun can be used because this information is encoded in the few
words that constitute the closed class of determiners.  So long as the
proportion of closed-class items in the lexicon is small relative to the
open-class items, the additional representational complexity that they
require will be more than offset by the reduction in complexity of the
very many more open-class items.  This is a very economical way to
minimise the storage requirements of the lexicon, and would presumably
translate into savings of metabolic and neural resources -- savings
which we can expect natural selection to favour.  We should also expect
a simpler lexicon to have fairly obvious advantages in terms of
learnability. 

	Examples of functional projections will be discussed in support
of these claims and further applied to illustrate how constraints like
the case filter and the extended projection principle are expected
consequences of an optimised lexicon, thereby relating these specific
constraints and their effects to natural selection for the first time. 
The role of iterated learning processes (Kirby & Hurford, 2002) in the
evolution of functional projections will also be discussed and related
to the proposal by Fukui (1995) that syntactic parameters are limited to
formal features of functional categories. 

Acknowledgement: This research was supported by EPSRC grant GR/N01118
 
Fukui, N.  1995.  The principles-and-parameters approach: a comparative
syntax of English and Japanese.  In T.  Bynon and M.  Shibatani, eds. 
Approaches to language typology.  Oxford: Oxford University Press. 

Hauser, M.  D., Chomsky, N., & Fitch, W.  T.  2002.  The faculty of
language: What is it, who has it, and how did it evolve? Science, 298,
1569-1579. 

Kirby, S., & Hurford, J.  R.  2002.  The emergence of linguistic
structure: An overview of the iterated learning model.  In A.  Cangelosi
& D.  Parisi (Eds.), Simulating the evolution of language.  London:
Springer-Verlag.