Burkhardt-Reed Megan M, Bene Edina R, Oller D Kimbrough
Department of Communication, Social Sciences Division, University of California, Los Angeles, Los Angeles, California, United States of America.
Origin of Language Laboratories, School of Communication Sciences and Disorders, University of Memphis, Memphis, Tennessee, United States of America.
PLoS One. 2025 Jan 9;20(1):e0308760. doi: 10.1371/journal.pone.0308760. eCollection 2025.
Speculations on the evolution of language have invoked comparisons across human and non-human primate communication. While there is widespread support for the claim that gesture plays a central, perhaps a predominant role in early language development and that gesture played the foundational role in language evolution, much empirical information does not accord with the gestural claims. The present study follows up on our prior work that challenged the gestural theory of language development with longitudinal data showing early speech-like vocalizations occurred more than 5 times as often as gestures in the first year of life. Now we bring longitudinal data on the second year (13, 16 and 20 mo), showing again that vocalizations predominated, and especially in conventional (learned) communication; > 9 times more spoken words were observed than gestures that could be viewed as functionally equivalent to words (i.e., signs). Our observations also showed that about ¾ of gestures across these second-year data were deictics (primarily pointing and reaching), acts that while significant in supporting the establishment of referential vocabulary in both spoken and signed languages, are not signs, but have single universal deictic functions in the here and now. In contrast, words and signs, the primary semantic components of spoken and signed languages, are functionally flexible, making possible reference to abstractions that are not bound to any particular illocutionary force nor to the here and now.
关于语言进化的推测引发了对人类与非人类灵长类动物交流的比较。尽管人们普遍支持这样的观点，即手势在早期语言发展中起着核心作用，甚至可能是主导作用，并且手势在语言进化中发挥了基础性作用，但许多实证信息并不符合这些关于手势的论断。本研究延续了我们之前的工作，我们之前的研究通过纵向数据对语言发展的手势理论提出了挑战，这些数据显示，在生命的第一年，类似言语的早期发声出现的频率是手势的5倍多。现在我们给出第二年（13、16和20个月）的纵向数据，再次表明发声占主导地位，尤其是在常规（习得）交流中；观察到的口语单词数量比可被视为在功能上等同于单词（即手语）的手势多9倍以上。我们的观察还表明，在这些第二年的数据中，约四分之三的手势是指示性的（主要是指和够），这些行为虽然在支持口语和手语中指示性词汇的建立方面很重要，但不是手语，而是在此时此地具有单一通用指示功能的行为。相比之下，单词和手语作为口语和手语的主要语义成分，在功能上具有灵活性，使得对不局限于任何特定言外之力或此时此地的抽象概念进行指称成为可能。
