University of Plymouth PEARL https://pearl.plymouth.ac.uk 04 University of Plymouth Research Theses 01 Research Theses Main Collection 2007 The Evolution of Language Universals: Optimal Design and Adaptation Turner, Huck http://hdl.handle.net/10026.1/1873 University of Plymouth All content in PEARL is protected by copyright law. Author manuscripts are made available in accordance with publisher policies. Please cite only the published version using the details provided on the item record or document. In the absence of an open licence (e.g. Creative Commons), permissions for further reuse of content should be sought from the publisher or author. The Evolution of Language Universals Optimal Design and Adaptation Huck Turner A thesis submilled in partial fulfilment of the degree of Doctor of Philosophy. Centre for Theoretical and Computational Neuroscience, University of Plymouth, UK. May, 2007 Jr.: vcrs^ycfPlj/mouth Library ':z :ri No. '""--.'.'mark Copyright © 2007 This copy of the thesis has been supplied on condition that anyone who consults it is understood lo recognise that its copyright rests with its author and that no quotation from the thesis and no information derived from it may be published without the author's prior consent. The Evolution of Language Universals Optimal Design and Adaptation by Huck Turner Abstract Inquiry into the evolution of syntactic universals is hampered by severe limitations on the available evidence. Theories of selective function nevertheless lead to predictions of local optimaliiy that can be tested scientifically. This thesis refines a diagnostic, originally proposed by Parker and Maynard Smith (1990), for identifying selective functions on this basis and applies it to the evolution of two syntactic universals: (I) the distinction between open and closed lexical classes, and (2) nested constituent structure. In the case of the former, it is argued that the selective role of the closed class items is primarily to minimise the amount of redundancy in the lexicon. In the case of the latter, the emergence of nested phrase structure is argued to have been a by-product of selection for the ability to perform insertion operations on sequences - a function that plausibly pre-dated the emergence of modem language competence. The evidence for these claims is not just that these properties perform plausibly fitness-related functions, but that they appear to perform them in a way that is improbably optimal. A number of interesting findings follow when examining the selective role of the closed classes. In particular, case, agreement and the requirement that sentences have subjects are expected consequences of an optimised lexicon, the theory thereby relating these properties to natural selection for the first lime. It also motivates the view that language variation is confined to parameters associated with closed class items, in turn explaining why parameter confiicts fail to arise in bilingualism. The simplest representation of sequences that is optimised for efficient insertions can represent both nested constituent structure and long-distance dependencies in a unified way, thus suggesting that movement is intrinsic to the representation of constituency rather than an 'imperfection'. The basic structure of phrases also follows from this representation and helps to explain the interaction between case and theta assignment. These findings bring together a surprising array of phenomena, reinforcing its correctness as the representational basis of syntactic structures. The diagnostic overcomes shortcomings in the approach of Pinker and Bloom (1990), who argued that the appearance of ^adaptive complexity' in the design of a trait could be used as evidence of its selective function, but there is no reason to expect the refinements of natural selection to increase complexity in any given case. Optimality considerations are also applied in this thesis to filter theories of the nature of unobserved linguistic representations as well as theories of their functions. In this context, it is argued that, despite Chomsky's (1995) resistance to the idea, it is possible to motivate the guiding principles of the Minimalist Program in terms of evolutionary optimisation, especially if we allow the possibility that properties of language were selected for non-communicative functions and that redundancy is sometimes costly rather than beneficial. Ill To Brett Jewell (1974-2001) for presenting me with a vision of my future, which I adopted as a template, a vision forged around a campfire and under a remote street lamp on a warm summer's night a long time ago. To Loretta Cadenaro for being prepared to take a bullet for me. And to Crimchy, a surprisingly well-fed stray cat. who recently taught me a thing or two about how natural selection works in practice. IV Contents ABSTRACT "I CONTENTS V LIST OF TABLES AND ILLUSTRATIONS IX ACKNOWLEDGEMENTS XI AUTHOR'S DECLARATION XIII PUBLICATIONS AND PRESENTATIONS XIV L INTRODUCTION 1 2. SYNTACTIC UNIVERSALS 9 2.1 APPROACHES TO THE STUDY OF UNIVERSALS 9 2. /. / The typological approach 9 2.1.2 The generative approach / / 2.1.3 The Mininialisi Program 2.2 LANGUAGE ACQUismoN 15 2.2./ Stages in language development /6 2.2.2 Creolisation and its implications /9 2.3 THE AUTONOMY OF GRAMMAR 23 2.4 SOME SYNTACTIC UNlVERSAl-S 28 2.4.1 Constituent structure 25 2.4.1.1 A brief review of ihe evidence 28 2.4.1.2 X-Bar Theory :-32 2.4.2 The lexicon •?7 2.4.3 Movement ^9 2.4.4 Binding 2.4.5 Case 2.4.6 Theta theory V 2.5 MLNIMALISTSYNTAX 46 2.6 SUMMARY ' 56 3. KVOLUTIONARY EXPLANATIONS ,.57 3.1 NON-SEIXCTIONIST CATEGORIES OF EXPl-ANATION 58 3.1.1 The lesson about spandrels: Concomitant changes 58 3.1.2 The lesson about exaptation: Current utility and historical origins 62 3.1.3 The lesson about the physical channel: Constraints on natural selection 65 3.1.4 The lesson about laws of growth and form: Non-adaptive elegance 69 3.1.5 The lesson about the role of genes and the environment 72 3.1.6 The lesson about cultural evolution 77 3. /. 7 Some conclusions about allegedly non-selectionist mechanisms 79 3.2 OPTtMALrrY AS A DIAGNOSTIC OF SELECTIVE FUNCTION 81 3.3 RECONCILING LINGUISTICS wrTH EVOLUHONARY BIOLOGY 89 3.3.1 The messiness of evolution and the elegance of language 92 3.3.2 Maladaptive consequences of grammatical universals 97 3.3.3 Mutants would have no one to talk to lOI 3.3.4 The lack of convincing adaptive e.xplanations 102 3.4 SUMMARY 104 4. THE EVOLUTION OF SYNTACTIC UNIVERSALS 108 4.1 BROADER ISSUES IN THE LANGUAGE EVOLUTION LITERATURE 108 4.1.1 Dating the origin of language 108 4.1.2 The evolution of the performance systems HI 4.1.3 The social functions of communication / 4.1.3.1 Vertal grooming I' 4 4.1.3.2 Cullural inherilancc ' 20 4.1.4 The evolution of the linguistic brain ^23 4.1.5 The evolution of the critical period in language acquisition /25 4.1.6 Stages in the evolution of language ^30 vi 4.2 THE EVOLUTION OF SYNTACTIC UNIVERSALS SPECIRCALLY 131 4.2.1 Sequential motor control representations exapied for syntax 131 4.2.2 Conceptual structure exapied for syntax 132 4.2.3 Syllable structure exapted for syntax i32 4.2.4 Compositionality 139 4.3 SUMMARY 141 5. CLOSED-CLASS ITEMS AND THE LEXICON 144 5.1 Cl-OSED-CLASS rrEMS AS AN ADAPTATION 144 5. /. I Redundancy in representations of syntactic distributions 145 5.1.2 Redundancy in representations of meaning /5/ 5.2 APPLYING THE OPTIMALrrY DIAGNOSTIC 155 5.2. / The strategy set 156 5.2.2 Optima I ity 157 5.3 SOMECONSEQUENCESOFTHETHEORY 159 5.3.1 Language variation and parameter-setting 159 5.3.2 Case theory 159 5.3.3 Agreement f60 5.3.4 The timing of the acquisition of open and closed classes 162 5.3.5 Tense and obligatory subjects /63 5.3.6 Closed-class items with identical distributions 164 5.3.7 Measuring the information content of lexical entries 165 5.4 COMPETING EXPLANATIONS 167 5.5 SUMMARY 168 6. PHRASE STRUCTURE AND SEQUENCES 171 6.1 THE OPTIMAL REPRESENTATION OF SEQUENCES 173 6.1.1 Proposal I: Indexing 173 6.1.2 Proposal 2: Pairs ^73 6.1.3 Proposal 3: Triples.. 174 vii 6.1.4 Proposal 4: Pairs reconsidered /SO 6.2 ALTERNATIVE METRICS 186 6.2.1 Optimal representations for deletion operations 186 6.2.2 Optimal representations for spelling out a linear sequence 187 6.2.3 Optimal representations for representing constituent structure 189 6.3 SOMECONSF.QUENCES AND FURTHER RERNEMENTS 190 6.3.1 Movement as by-product ^90 6.3.2 The status of the command relation /92 6.3.3 Feature checking /97 6.3.4 Lexical features and linearization sets 205 6.3.5 Theta roles and case assignment 206 6.4 SUMMARY 207 7. DISCUSSION....; 212 7.1 METHODOLOGICAL CONTRIBUTIONS 212 7. /. / The lack of non-selectionist categories of explanation 213 7.1.2 The irrelevance of communicative functions 214 7.1.3 The irrelevance of design complexity 2/5 7.1.4 The optimality diagnostic 2/5 7.1.5 A narrower view of perfection for the Minimalist Program 216 7.2 EMPIRICAL CONTRIBUTIONS 218 7.2. / Closed-class items and the lexicon 2/5 7.2.2 Phrase structure and sequences 2/9 7.3 REMAINING QUESTIONS 220 7.3.1 Alternative sources of fit 220 7.J.2 Optimality and stability 222 7.4 NEW HORIZONS 224 REFERENCES 226 APPENDIX A: PUBLICATIONS 239 viii List of Tables and Illustrations Chapter 2 23. X-Bar schema 34 25.