Steven Pinker and Ray Jackendoff challenge the hypothesis that the only uniquely human aspect of language is syntactic recursion, arguing that this view ignores many other aspects of language that are uniquely human, such as phonology, morphology, case, agreement, and word properties. They also argue that the hypothesis is inconsistent with the anatomy and neural control of the human vocal tract and is weakened by experiments showing that speech perception cannot be reduced to primate audition, word learning cannot be reduced to fact learning, and that at least one gene involved in speech and language was evolutionarily selected in the human lineage but is not specific to recursion. The recursion-only claim is motivated by Chomsky's Minimalist Program, which de-emphasizes the same aspects of language. However, the authors argue that this approach is problematic and cannot be used to support claims about evolution. They contest related arguments that language is not an adaptation, namely that it is "perfect," non-redundant, unusable in any partial form, and badly designed for communication. The authors suggest that the hypothesis that language is a complex adaptation for communication which evolved piecemeal avoids all these problems. They also argue that there are many aspects of language that are uniquely human, including conceptual structure, speech perception, speech production, phonology, and syntax, which are not recursive. They conclude that the recursion-only hypothesis is hard to sustain and that there is considerably more of language that is special, though still a plausible product of the processes of evolution. They also argue that the hypothesis that recursion is the only aspect of language that is special to it, that it evolved for functions other than language, and that this nullifies "the argument from design" that sees language as an adaptation is not supported by the evidence. The authors agree with HCF that it is conceptually useful to distinguish between the language faculty in its broad and narrow sense, and that the language faculty evolved in the human lineage for the communication of complex propositions. They also agree that the rigorous laboratory study of possible homologues and analogues of aspects of language in other species is a hallmark of the research programs of Hauser and Fitch, and that they promise major advances in our understanding of the evolution of language. However, they disagree specifically on the hypothesis that recursion is the only aspect of language that is special to it, that it evolved for functions other than language, and that this nullifies "the argument from design" that sees language as an adaptation. The authors conclude that there is a substrate of conceptual structure in chimps, overlain by some uniquely human but not necessarily language-based subsystems, in turn overlain by subsystems that depend on the pre-existence of linguistic expression. They also argue that phonology is a major counterexample to the recursion-only hypothesis, as it is specific to language, uniquely human, discretely infinite, and not recursive. They conclude that words are a distinctive language-specific part of human knowledge, andSteven Pinker and Ray Jackendoff challenge the hypothesis that the only uniquely human aspect of language is syntactic recursion, arguing that this view ignores many other aspects of language that are uniquely human, such as phonology, morphology, case, agreement, and word properties. They also argue that the hypothesis is inconsistent with the anatomy and neural control of the human vocal tract and is weakened by experiments showing that speech perception cannot be reduced to primate audition, word learning cannot be reduced to fact learning, and that at least one gene involved in speech and language was evolutionarily selected in the human lineage but is not specific to recursion. The recursion-only claim is motivated by Chomsky's Minimalist Program, which de-emphasizes the same aspects of language. However, the authors argue that this approach is problematic and cannot be used to support claims about evolution. They contest related arguments that language is not an adaptation, namely that it is "perfect," non-redundant, unusable in any partial form, and badly designed for communication. The authors suggest that the hypothesis that language is a complex adaptation for communication which evolved piecemeal avoids all these problems. They also argue that there are many aspects of language that are uniquely human, including conceptual structure, speech perception, speech production, phonology, and syntax, which are not recursive. They conclude that the recursion-only hypothesis is hard to sustain and that there is considerably more of language that is special, though still a plausible product of the processes of evolution. They also argue that the hypothesis that recursion is the only aspect of language that is special to it, that it evolved for functions other than language, and that this nullifies "the argument from design" that sees language as an adaptation is not supported by the evidence. The authors agree with HCF that it is conceptually useful to distinguish between the language faculty in its broad and narrow sense, and that the language faculty evolved in the human lineage for the communication of complex propositions. They also agree that the rigorous laboratory study of possible homologues and analogues of aspects of language in other species is a hallmark of the research programs of Hauser and Fitch, and that they promise major advances in our understanding of the evolution of language. However, they disagree specifically on the hypothesis that recursion is the only aspect of language that is special to it, that it evolved for functions other than language, and that this nullifies "the argument from design" that sees language as an adaptation. The authors conclude that there is a substrate of conceptual structure in chimps, overlain by some uniquely human but not necessarily language-based subsystems, in turn overlain by subsystems that depend on the pre-existence of linguistic expression. They also argue that phonology is a major counterexample to the recursion-only hypothesis, as it is specific to language, uniquely human, discretely infinite, and not recursive. They conclude that words are a distinctive language-specific part of human knowledge, and