The representation of animal communication and language evolution in introductory linguistics textbooks

Abstract

The last three decades have brought a wealth of new empirical data and methods that have transformed investigations of language evolution into a fast-growing field of scientific research. In this paper, we investigate how the results of this research are represented in the content of the most popular introductory linguistic textbooks. We carried out a comprehensive computer-assisted qualitative study, in which we inspected eighteen English-language textbooks for all content related to the evolutionary emergence of language and its uniqueness in nature, in order to evaluate its thematic scope, selection of topics, theories covered, researchers cited, structural soundness, currency, and factual accuracy. Overall, we found that the content of interest lacks a defined canonical representation across the textbooks. The coverage of animal communication was relatively broad, with some recurring classic examples, such as vervet monkeys or honeybees; this content was mostly structured around the ‘design features’ approach. In contrast, the coverage of topics related to language origins and evolution was much less extensive and systematic, and tended to include a relatively large the proportion of content of historical value (i.e. creation myths, ‘bow-wow’ theories). We conclude by making recommendations for future editions of textbooks, in particular, a better representation of important frameworks such as signalling theory, and of current research results in this fast-paced field.

1. Introduction

Research on the origins and evolution of language origins has a troubled history of being viewed as unscientific (see e.g. Whitney 1873[1872], Doerfer 1973, Fisiak 1985; for a discussion, see Kaplan 2021). However, as also stressed in a number of recent introductions to this field (e.g. Fitch 2010, 2017; Gong et al. 2014; Dediu and de Boer 2016; Progovac 2019; Boeckx 2021), the field has transformed significantly. It no longer can be seen as armchair philosophizing producing just-so-stories (Gould and Lewontin 1979; cf. Lewontin 1998), or a kind of ‘intellectual game’ (Kendon 1991: 202). Instead, it has progressed to regular research centred around the day-to-day addressing of solvable Kuhnian puzzles, including both empirical research and carefully constructed theoretical models. In particular, the perception of language evolution as a scientific field has been academically consolidated in terms of institutional indicators, such as prestigious flagship publications, research centres, funded projects, conferences, and journals (see esp. Dediu and de Boer 2016), to yield a program that is institutionally as well as theoretically progressive (Lakatos 1978; for a discussion, see Żywiczyński 2018: 200–202). In sum, it is fair to say that ‘[r]esearch on language evolution is undoubtedly among the fastest-growing topics in linguistics’ (Nölle et al. 2020).

Has all of this progress also percolated to the teaching of linguistics, as reflected in the content of linguistics textbooks? Introductory textbooks are generally seen as places where Kuhnian ‘“normal science” is defined and acknowledged fact is represented’ (Hyland 2004: 105). They thus serve an important function of ‘canonizing discourse’ within a discipline (Brown 1993; cf. Hyland 2004; Love 2006). That is, they provide an orthodox, coherent ‘epistemological map’ of the landscape of the discipline and what it is about (Hyland 2004: 105). In fact, many students view introductory textbooks as representing ‘concrete embodiments of the knowledge of their disciplines’ (Hyland 2004: 105). Textbooks are, therefore, an important source for students to develop academic literacy in a discipline and become acculturated into it (Johns 1997; Love 2006). As Myers (1992: 3) puts it, ‘writing and reading [textbooks] reproduces knowledge and reproduces academics’. As outlined above, language evolution research has reached the stage of Kuhnian ‘normal science’ and is playing an expanding and important role in the language sciences. As such, it should be well represented in introductory linguistic textbooks, given that these texts strive to offer a ‘balanced and uniformly excellent coverage of the full range of modern linguistics’ (Fasold & Connor-Linton), address ‘all the topics that a student will need in their study of language’ (McGregor), and ‘up-to-date coverage of all the important areas of linguistics’ (O’Grady et al.).

In 2016, in a conference abstract, we reported on an exploratory investigation of topics related to language evolution research in fourteen introductory-level linguistic textbooks, finding that language evolution was not given the same status as, for example, language acquisition, language change, language and the brain, language and culture, or language and society, which are most extensively covered. We also judged that ‘the teaching of language evolution to students of general linguistics rests on out-dated and largely inadequate conceptual frameworks, and fails to communicate major theoretical breakthroughs and empirical results’ (Wacewicz et al. 2016). Here, we revisit this issue with more rigorous tools and an updated and extended scope. Specifically, we investigate what introductory textbooks say about two closely intertwined (see, in particular, the now-classic work by Hockett 1960 and Hauser et al. 2002) topics: the questions on how language emerged and how it differs from the communication of non-human animals (henceforth: animals). In this paper, we present a first-of-its-kind, large computer-assisted qualitative study, in which we inspected eighteen textbooks for all contents related to the evolutionary emergence of language and its uniqueness in nature, in order to evaluate its thematic scope, selection of topics, theories covered, researchers cited, structural soundness, currency, and factual accuracy. Our primary goal is to guide better-quality teaching to the new generations of linguists, but our study may also serve as a blueprint for similar projects in other areas relevant to linguistics, as well as in other disciplines.

2. Materials and Methods

2.1 Materials and design

To evaluate the popularity and influence of linguistic textbooks, we consulted Open Syllabus (OS), a non-profit service with a corpus of over nine million English-language syllabi from 140 countries (https://opensyllabus.org).¹ Based on the OS popularity metrics, OS appearances, and OS score (as of 20 January 2021—see Table 1), we selected sixteen general introductory textbooks to linguistics, which we complemented with two very recent textbooks. In our analyses, we worked with the most recent edition of each textbook available as of 20 January 2021.

2.1.1 Scope of the analysis

The content of interest for our analyses can be described as any content related to the origins of language and its status among animal communication systems, or more generally, a species-comparative or evolutionary perspective on language. This thematic range closely matches the scope of the Evolang, http://evolang.org/, conference series, which is commonly regarded as the main conference in this field and often assumed as a reference point in language evolution research (Bergmann and Dale 2016; Wacewicz and Żywiczyński 2017). Hence, in order to help operationalize the exact thematic profile of the content to be coded, we stipulated it as ‘content with a good fit to the Evolang conference’. Following up on Wacewicz et al. (2016; see also Bergmann and Dale 2016, on the main Evolang topic clusters), we divided the content top-down into two main thematic categories of interest as Animal Communication and Language Evolution (comprising both explanations of how language originated and interdisciplinary research relevant to language evolution, but excluding purely historical language change). Including animal communication in addition to language evolution was motivated by the fact that the comparison of human and non-human communication systems represents one of the most central methods for the investigation of the evolution of language. Finding similarities and differences between aspects of human language and the communication systems of other animals can be informative as to the evolutionary foundations of language and evolutionary pressures shaping it. As such, the comparative methods are well represented in work on language evolution (e.g. Fitch 2010; Tallerman and Gibson 2012; Macmahon and McMahon 2013). For example, at the recent Joint Conference on Language Evolution (https://sites.google.com/view/joint-conf-language-evolution/home) in Kanazawa, Japan, in August 2022, out of the 196 plenaries, invited talks, talks, and posters, 43 (22%) were on animal communication and cognition. We coded passages appearing anywhere in the content of each book, including boxes, footnotes, captions, and exercises (but not indexes or references). Section 2.2 explains the details of the coding procedure, and Section 3.1 provides a more detailed breakdown and discussion of the final set of codes and categories.

2.2 Procedure

The material was coded by two expert coders (AP, AS) with the computer-assisted qualitative research software NVivo 1.3 (QSR International Pty Ltd., released August 2020), in collaboration with two language evolution experts (SW, MP).

The cyclical coding/re-coding process was completed in five steps (cf. Saldaña 2015):

• 1) Training: Two coders were trained with a training set consisting of excerpts from two textbooks. The coders were instructed to identify and mark all passages related to language origins, language evolution, or animal communication as described above, assuming one sentence as a minimal passage and one paragraph as a maximum passage. Each of the identified passages was assigned a short label, that is, a code. The coders were instructed to adopt a bottom-up approach and use the topics discussed at the Evolang conferences as the reference point for coding. Two language evolution experts provided feedback.

• 2) Individual open coding: each textbook was open coded by the two expert coders, working independently of each other. The coders identified the relevant passages through a three-step procedure:

  • (a) The coder analysed the table of contents and the indexes of each textbook to pre-select the potentially most relevant chapters, sections, and pages for close reading;

  • (b) The coder then manually skimmed the full content of each textbook;

  • (c) Finally, the coder completed a series of targeted keyword searches for a broad range of general keywords (e.g. evolution, emergence, origins, etc.) and specific keywords including names of animal species, names of disciplines (e.g. archaeology), and key concepts (e.g. FOXP2).

The coders coded all identified passages in the bottom-up approach described above.

• 3) Consensus I: in the first consensus phase, the output files from both expert coders were merged into a single NVivo file, containing over 1000 codes. The coders discussed each coded passage to arrive at a consensual coding and synthesized the material into a hierarchical structure of codes and categories (cf. Saldaña 2015). The coding scheme was progressively updated in the process, resulting in a roughly twofold reduction in the number of codes.

• 4) Verification: in this step, two language evolution experts (MP, SW), working together, reviewed the correctness of the coding scheme. The two language evolution experts discussed each coded passage and recommended changes to be considered in the next consensus phase as discussion points. They also did an additional manual skimming of the full text of each book. Additionally, they evaluated the coded passages for the factual accuracy of the information contained therein. This resulted in an additional set of codes and their annotations (see below, Section 4.1), which were then incorporated into the NVivo codebook.

• 5) Consensus II: all passages marked during the verification phase as discussion points were discussed together by all four experts to determine consensual coding and consensual classification into categories. This led to a final total of 462 codes and coding categories, available in Supplementary Material.

3. Analysis

3.1 Topics overview

The main categories of investigation are presented here in a top-down manner. First, we will deal with the question of how many textbooks mention our two main coding categories: Animal Communication and Language Evolution.

First, only the Language Files, O’Grady et al.² and Yule have chapters on Animal Communication, and only Yule has a chapter on Language Evolution. Five other textbooks have sections dedicated to Animal Communication. Four other textbooks have sections dedicated to Language Evolution (see Table 1). However, it has to be noted that these sections also differ in length, ranging from less than one page to several pages. Out of eighteen textbooks, three do not make any references to either Animal Communication or Language Evolution. For the remaining fifteen, references to Animal Communication and Language Evolution can be further sub-categorized (see Figs. 1 and 2). For Animal Communication, there were three emergent broad topics (subcategories), and for Language Evolution, there were two subcategories.

Main category: Animal Communication

Subcategories:

• Animal communication behaviours: References to specific animal communicative behaviours or general characterizations of aspects of animal communication,

• Animal versus human communication: Comparisons of animal versus human communication,

• Language-trained animals: References to research with language-trained animals.³

Main category: Language Evolution

Subcategories:

• Language origin theories: References to explanations of how language originated. This category includes references to larger theoretical frameworks as well as more specific scenarios of language origins, most of them historical rather than contemporary. Examples include creation myths like the story of Babel, historical onomatopoeic hypotheses of language emergence, or modern-day scientific accounts such as Dunbar’s gossip theory of language origins (Dunbar 1996).

• Language evolution research: References to interdisciplinary research directly connected to the field of language evolution (see Section 2). This category includes passages that do not describe a particular account or scenario of language origins, but instead present results and data, mostly empirical and relatively recent, that provide an evidential basis for inferences about the evolutionary history of language, and empirical and theoretical building blocks for scenarios and theories. Examples include references to the relevant fossil record (e.g. hominin braincases or speech organs), or relevant genetic research (e.g. the FOXP2 gene in ancient humans). Importantly, other bodies of research that are often drawn on to inform evolutionary scenarios (such as on language ­acquisition, sign language, neurolinguistics, or historical linguistics⁴) were not included as a default—we only did so when they were presented in a context relating them to the questions of the evolutionary emergence and development of language in human phylogeny. This decision is based on the fact that these areas of research on their own are not only independent subjects of linguistic study, but also because they are most frequently not discussed in an evolutionary framework or with respect to their potential implications for language evolution.

3.1.1 Results

There are two main general findings: firstly, references to Animal Communication (80.4% of coded references) are overall much more frequent than to Language Evolution (19.6%), and secondly, there is significant variation between textbooks in the extent of coverage and selection of topics.

Regarding the subcategories of Animal Communication, these are roughly distributed evenly within that category, with 35.5% of references to specific animal communicative behaviours, 32.7% of references comparing animal and human communication, and 32.8% of references discussing language-trained animals. Within the category Language Evolution, results are also evenly split, with 50.2% of references to language evolution research, and 49.8% of references to specific language origin theories.

Secondly, the number of references to Animal Communication and Language Evolution differs significantly from textbook to textbook. As already mentioned, three textbooks do not include references to these topics at all, and a number of them also only make very little reference to these topics. The bulk of references come from ten textbooks, which, however, still vary quite extensively in their coverage, from 32 (Fasold & Connor-Linton) to 318 references (O’Grady et al). An overview of the frequencies of topics by textbooks can be seen in Fig. 1.

Moreover, as can be seen in Fig. 2, textbooks also differ in how much they discuss a particular topic, for example, the degree to which they discuss animal versus human communication, language-trained animals, and the other categories.

3.2 Animal communication

3.2.1 Animal communication behaviours

Thirteen out of fifteen textbooks (87%, with the exception of Bauer and Hayes) make references to specific animal communicative behaviours or general characterizations of aspects of animal communication. Among those, references to primate communication are most frequent (12 textbooks, 125 references), followed by birds (7 textbooks, 108 references), arthropods, especially bees (11 textbooks, 82 references), and mammals other than primates (12 textbooks, 56 references). Overall, textbooks differ quite strongly in which specific animal communicative behaviours they refer to. This also holds for references to species. Textbooks reference a total of sixty-three different species. However, forty-four (69.8%) of these species are only mentioned in one textbook, and only four species/clades (6.3%) are mentioned in five textbooks or more. These are vervet monkeys (five textbooks), chimpanzees (six textbooks), dogs (seven textbooks) and honeybees (eleven textbooks).

In addition, sometimes textbooks also make more general statements, for example, about monkeys or primates, fish, or songbirds. Some textbooks also mention more general properties of animal communication, for example, discussions of non-vocal communication and whether animal signals are innate or learnt. Furthermore, some textbooks also discuss the general properties of animal signs, such as animal signs as expressions of emotional states, graded instead of discrete signals, and their limited range of meanings.

3.2.2 Animal versus human communication

Fourteen out of fifteen textbooks (93.33%, with the exception of Dirven & Verspoor) include an explicit comparison of human language with the communication systems of non-human animals. As outlined in Section 3.1, three of them have chapters dedicated to animal communication or chapters on animal versus human communication.

As shown in Fig. 3, the two topics that are mentioned by most textbooks are human language as a species-specific trait (11 textbooks, 24 references), as well as discussions of animal versus human communication in the context of Hockett’s design features (11 textbooks, 183 references).

Another prominent topic is discussions of the biological differences between humans and animals. A number of textbooks also discuss animals’ ability to learn and understand human language and differences in the cognitive abilities of animals and humans. Also frequent are specific comparisons between humans and chimpanzees and the claimed distinction that human communication is stimulus-free whereas animal communication is stimulus bound.

The last group of topics is differences between the features of human language and animal communication that are not captured by Hockett’s design features. These include the degree of iconicity in human language versus animal communication, the pragmatic function of human language, differences in the mode of communication, the property of redundancy in communication systems, and turn-taking as a characteristic property of human communication.

In terms of the number of references to concepts, references to Hockettian design features of language far outweigh all other references.

For this reason, we are now going to turn to discussions of Hockettian design features of the language. Out of the eleven textbooks that mention such features, only four (36.4%) explicitly mention Hockett by name and six (55.55%) reference the characteristic properties of human language as ‘design features’. All eleven, however, mention properties that were popularized by Hockett, either directly using Hockett’s terminology or expressing the same concept (see Fig. 4).

3.2.3 Language-trained animals

Discussions of ‘language-trained animals’, that is, animals exposed to some kind of sign system, can also be found frequently in textbooks. They can be found in ten out of fifteen textbooks (66.67%, with the exception of Bauer, Dirven and Verspoor, Hayes, Hazen and Meyer). Textbooks focus mostly on research with great apes, which are mentioned in ten textbooks, whereas studies with parrots and dogs are both mentioned in four textbooks (40%). Only one textbook also reports on research with dolphins.

Regarding the great apes, all ten textbooks mention language-trained chimpanzees, eight mention bonobos; seven mention gorillas, and two textbooks also mention language-trained orangutans.

A sceptical perspective on language-trained animals is prevalent with eight textbooks discussing scepticism towards these experiments, and seven textbooks discussing these experiments in the context of stimulus-response conditioning. Three textbooks explicitly discuss the question of to what degree language-trained animals can be said to have acquired symbols, and three textbooks discuss the question if chimpanzees have acquired syntactic knowledge. Five textbooks explicitly compare humans’ and primates’ abilities to learn a language.

3.3 Language evolution

References in the category Language Evolution can be found in fifteen textbooks. However, as already shown in Table 1 and Fig. 1 (cf. Section 3.1), textbooks differ quite significantly in how much space they give to this topic and also in which research and language origin scenarios they discuss. As already mentioned, only Yule has a chapter dedicated to language evolution, and only Denham & Lobeck, Finegan, Hayes, and McGregor have dedicated sections on language evolution. But even here the amount of space devoted to language evolution differs, ranging from less than one page to six pages. The other textbooks sometimes only discuss language evolution in passing.

3.3.1 Language evolution research

Regarding the topics discussed, twelve textbooks make reference to biological aspects of human evolution (fifty-three references). This includes references to the evolution and structure of the human brain (eight textbooks, thirteen references), the FOXP2 gene (seven textbooks, sixteen references), and the evolution and structure of the human speech organs (five textbooks, eight references). Other topics in this area that are also mentioned are the evolution of bipedalism (three textbooks, four references), changes of the digestive and respiratory system (one textbook, two references), and handedness (one textbook, one reference). One other frequent feature is that many textbooks (eight textbooks, thirteen references) discuss that there is still much scepticism towards language evolution research and that many proposals are speculative. Explicitly positive attitudes towards the field of language evolution and its future are only expressed in two textbooks (Finegan and McGregor). Other topics discussed in a number of textbooks are extinct hominins (six textbooks, fifteen references), archaeological evidence (five textbooks, six references), and that language evolution research is an interdisciplinary endeavour. An overview of the main topics discussed and their frequencies can be found in Fig. 5.

As illustrated by Fig. 6, textbooks also differ considerably in the potential timeframes of language emergence, with estimates in eight textbooks ranging from 50 000 years ago to as much as 500 000 years ago, and even older estimates for related capacities such as the evolution of ‘speech areas’ of the brain (2 million years ago) or the ‘capacity for language-type communication’ (2.6 million years ago).

3.3.2 Language origin theories

Twelve textbooks mention language origin scenarios (with the exception of Dirven & Verspoor, Hayes and Hazen). As Fig. 7 shows, the most frequently mentioned factor is language as an evolutionary adaptation (seven textbooks, eleven references) and discussions of the evolution of the properties of the faculty of language (six textbooks, fourteen references). Notably, cultural evolution is only mentioned explicitly in one textbook (McGregor, three references), which we consider a major oversight (see Section 4.3.2). Another frequently discussed topic is divine origins myths, which can be found in five textbooks (thirty-two references). Equally frequent are discussions of social factors involved in the emergence of language (five textbooks, thirteen references) and the question in which modality language began, that is, if it was primarily vocal, gestural, or multimodal at first (five textbooks, nine references). Other aspects of language origins scenarios are discussed infrequently. This includes references to onomatopoeic scenarios of language evolution (three textbooks, seven references), the role of tool use in language evolution (three textbooks, seven references), the relationship of music and language in language evolution (two textbooks, three references), and catastrophic origin theories (four textbooks, nine references). In contrast, explicit references to gradualistic theories of language evolution can only be found in one textbook (Fromkin et al.). The same holds for the important concept of protolanguage as an intermediary stage before fully modern language (e.g. Tallerman 2012), which is only mentioned in one textbook (Fasold & Connor-Linton).

4. Evaluation and Discussion

4.1. Suggestions and resources for improvement

In this section, we offer some short notes on suggestions for improvements for introductory textbooks, along with suggestions for good resources regarding language evolution research (see Box 1).

Overall, we found that the number of problematic passages about language evolution and animal communication was relatively low, with a total of sixty problematic passages of different dimensions found in all textbooks (thirty-eight for animal communication and twenty-two for language evolution).⁵ The most frequent inaccurate statement concerns non-human primate vocal anatomy, with the claim that the vocal tracts of non-human primates are anatomically incapable of producing speech sounds. This has been demonstrated by more recent research to be inaccurate (e.g. Fitch 2000; Fitch et al. 2016). However, given that this is a relatively recent research development, it is understandable why it hasn’t permeated introductory textbooks yet.

One aspect we judged to be more problematic is that some textbooks (Akmajian et al., Fasold & Connor-Linton, Rowe & Levine) make extensive reference to popular press publications, which in addition sometimes are also quite outdated. For example, in the 2017 edition of their textbook, Akmajian et al. cite a 1989 National Geographic Magazine article on the speech capacities of Neanderthals.

In addition, some textbooks, including Yule, cite and draw conclusions from research on the famous alarm call system of vervet monkeys alone (e.g. Cheney and Seyfarth 1990). Here, we suggest that introductory textbooks could profit from including more recent work on more complex signalling systems, such as those found in putty-nosed monkeys (Arnold and Zuberbühler 2006) and Campbell’s monkeys (Zuberbühler 2002; Ouattara et al. 2009), among others (see e.g. Townsend and Manser 2013; Engesser and Townsend 2019; Suzuki and Zuberbühler 2019, for recent overviews).

In Box 1, we list some useful recent resources that introductory textbooks could use to improve their representation of language evolution research (see also Box 2). In addition, Johansson (2020) offers a comprehensive bibliography of language evolution research.

4.2. Animal communication

4.2.1 Hockett’s design features

Section 3.2.2 reveals that the received way of comparing language with animal communication is through the list of ‘design features’ based more or less closely on those proposed by Hockett (esp. 1960, but see also Hockett 1958, 1959; 1966). This is understandable, given that the Hockettian system is still the classic, best known, and widely accepted system of comparing animal communication to language (e.g. Beecher 2021) and has been highly influential both in and beyond linguistics, in fields such as ethology (e.g. Hinde 1982), biosemiotics (Noth 1990), and also language evolution (e.g. Fitch 2010; Cuskley 2020). However, more than 60 years have passed since Hockett’s first proposals (1958, 1959), meaning that some of the deeper theoretical foundations of Hockett’s system rest on an outdated understanding of both biology and linguistics.

Biologically, Hockett’s approach is implicitly informed by once-popular misconceptions including that of evolution proceeding exclusively through incremental progressions, or anthropocentric views of animal communication systems as ‘incomplete languages’. We suggest that while Hockett’s design features might prove a good entry point to comparisons of human language and animal communication systems, textbooks would profit from extending their discussions by including insights from signalling theory (see Section 4.2.2). In contrast, Hockett’s approach rests implicitly on the ‘classic ethological’ model of communication, which is no longer supported in behavioural ecology (see Searcy and Nowicki 2005: 7–9). From the point of view of linguistic theory, the Hockettian system inevitably reflects the mid-20^th-century understanding of what language is, with a heavy focus on its formal and structural properties; even if not incorrect, this understanding is at least incomplete, through its neglect of more recent cognitive, functional and interactionist perspectives (see esp. Wacewicz and Zywiczynski 2015).

In sum, the Hockettian system of design features has long been a cornerstone of understanding the status and origins of language, and its classic status still translates into its considerable descriptive and educational utility. However, textbooks would benefit from an overhaul of this system to the inclusion of more recent perspectives. Small steps in this direction are already evident in some textbooks. For example, O’Grady et al. feature a text box on ‘Updating the Design Features of Language’ with reference to a recent paper by Hauser et al. (2014). However, these attempts are unsystematic and not yet standardized. In Box 2, we briefly describe several points that we see as deserving inclusion.

4.2.2 Signalling theory

In biology, the received approach to studying the form, function and in particular evolution of animal communication is signalling theory: it is ‘the main body of theory applied to animal communication’ (Power 2014: 50), and it underlies contemporary textbooks on this topic (e.g. Maynard Smith and Harper 2003; Searcy and Nowicki 2005; Bradbury and Vehrencamp 2011). Signalling theory is a theoretical framework that applies neo-Darwinian principles to the study of communication. From that perspective, it construes communicators as agents designed to maximise their evolutionary fitness, and communication, like all behaviour, is seen as a tool for such fitness maximization. This perspective is interested in the underlying economics of communication, that is, what the animal stands to lose versus what it stands to gain from the communicative interaction. These costs and benefits ultimately affect the animal’s evolutionary fitness, and in this way, they translate into selection pressures shaping the evolution of communication systems. In particular, a central tenet of signalling theory is that the ‘goal’ of communication, understood from that perspective as its evolved function, is not to provide information to others—since making investments into the fitness of unrelated individuals instead of one’s own would be biologically inexplicable. Rather, the ‘goal’ of communication is to pursue one’s own fitness-enhancing goals, such as, for example, advertising one’s biological quality to potential mates, which can be trivialized into saying that communication is ‘self-interested’.

Signalling theory thus elucidates the deeper design principles of all animal communication. It is, therefore, fundamental from the species-comparative perspective, as it provides the only established unified framework to study all animal communication systems that do not presuppose language as a special case or a reference point. Signalling theory makes it possible to understand the design reasons for the limited range of expression in non-human animals (esp. Heintz and Scott-Phillips 2022), or explain certain unexpected patterns in the relation between communicative and cognitive capacities, such as the advanced communication system in honeybees (e.g. Wacewicz and Żywiczyński 2018). Most importantly, this perspective also clearly and independently identifies important ways in which human language stands out in nature (cf. esp. Knight 2016; Dessalles 2020). This is mostly related to the through-and-through cooperativeness of language, which is taken for granted in linguistics, but not normally expected in animal communication systems. This is as important for the species-comparative perspective as it is for research on the evolutionary origins of language, where the emergence of cooperative signalling as well as its continued evolutionary stability is considered a ‘central problem’ (e.g. Maynard Smith and Harper 2003; Fitch 2010; Heintz and Scott-Phillips 2022). Adding the perspective of signalling theory to textbooks would improve the theoretical context for discussing communication systems, and the differences and similarities between human language and non-human animal communication systems.

4.3 Language origins

Sections 3.3.1 and 3.3.2 reveal a relative paucity of information on those topics, especially when compared to much more extensive and detailed coverage of animal communication (see Fig. 2). While a majority of textbooks include mentions of language origins and language evolution research, only one textbook has a chapter on this topic and two more have sections extending beyond a single page. Further, we see a disproportionate representation of content of purely historical value, in particular, divine or mythical accounts of language origins (such as the story of Babel), or accounts developed in the 19th century (e.g. the ‘bow-wow’ or ‘pooh-pooh’ theories of language emerging from mimicking animals or from emotional cries). The inclusion of such themes may be substantiated on historical grounds as classic points of reference in the debates of language origins; however, their over-representation relative to the current state of the art may be felt as painting an unfavourable picture of contemporary language evolution research.

A particularly interesting example is Yule, the only textbook with a whole chapter dedicated to the topic of language origins. It is divided into sub-chapters representing several ‘sources’ of language: the divine source, the social interaction source, the natural sound source, the tool-making source, the physical adaptation source, and the genetic source. This presentation is problematic on a number of grounds. First, such a structuring juxtaposes explanations on incomparable levels (Tinbergen 1963): implementation, versus adaptive function, versus phylogeny—that is the underlying physiological implementation of a feature, versus the selection pressures shaping it, versus its development in the species. For example, the level of physical implementation, here discussed in terms of the speech-adapted anatomy of the vocal tract, is listed in parallel to the level of genetic specification, even though the former is clearly causally dependent on the latter rather than being a ‘different source’. Furthermore, a juxtaposition of natural and supernatural ‘sources’ poses the danger of casting unscientific approaches as equal-status contenders—not only through the structure of subchapters already mentioned, but occasionally through unfortunate phrasing, for example, ‘If human language did emanate from a divine source, we have no way of reconstructing that original language, especially given the events in a place called Babel, <because the Lord did there confound the language of all the earth,> as described in Genesis’ (11: 9).

Another notable example is McGregor. This textbook presents an explicitly favourable evaluation of the field of language evolution research (pages 265, 267—the only such textbook except for Finegan), and it offers a relatively brief but accurate and up-to-date coverage of this field, with a good selection of the most influential theories and relevant bodies of evidence. On the other hand, McGregor inexplicably extends Max Müller’s derogatory ‘bow-wow’ terminology to these approaches, using the labels ‘noddy’ (the gestural approach), ‘yackety-yack’ (Dunbar’s grooming hypothesis), and the ‘just genes’ theory, further subdivided into the ‘oops!’ and ‘chatting-up’ theories, which stand for the views of Chomsky and Pinker, respectively. As noted, for example, by Sprinker (1980: 117), ‘it is hard to suppress one’s natural amusement when discussing them under such labels. […] [I]t is sometimes difficult for us to [take such ideas seriously], particularly with the persistent ring of Muller’s appellatives in our ears’.

4.4 Language evolution research

4.4.1 Genetic, fossil, and material-culture data sources for modern language evolution research

As shown in Section 3, textbooks do not rely extensively on the bodies of data that go beyond comparative evidence from animals. Of these, genetic evidence, and specifically the FOXP2 gene, is referenced relatively frequently (seven books, sixteen references), but information provided on this particular topic is often problematic (see Appendix A.1 in Supplementary Material). Palaeoanthropological and archaeological information is typically absent from textbooks or only mentioned as isolated facts (fossil record: three books, four references; extinct hominins: six books, fifteen references; archaeology: five books, six references).

Still, the recently available genetic, fossil, and material-culture record of extinct hominins does allow us to shed considerable light on their linguistic abilities. Arguably the most interesting example, also for its significance to the science of language, is the strong interdisciplinary evidence pointing to the presence of recognizably human-like forms of communication in Neanderthals (see esp. Botha 2020, for a critical overview). First cases for Neanderthal language backed up by comprehensive multidisciplinary evidence became available already a decade ago (e.g. Dediu and Levinson 2013), and additional evidence has accrued since then, such as on systematic neanderthalensis—sapiens interbreeding, the presence of the same derived mutations of the FOXP2 gene, very similar speech production and hearing apparatuses, and behavioural modernity of Neanderthals (see e.g. Johansson 2015, Dediu and Levinson 2018, for reviews).

Of course, we cannot say with absolute certainty whether Neanderthals did or did not have language (Berwick et al. 2013; Botha 2020). Nevertheless, the perception that arguments regarding language in the prehistoric past must solely rely on speculation is no longer true. The last two to three decades have dramatically expanded the evidential basis for inferences about the language capacities of ancient hominins, making such inferences more robust through grounding them in multiple lines of converging evidence. Further, as shown above, it currently appears that the extent and weight of this converging evidence make it reasonable to change the null hypothesis: the bulk of evidence makes assuming the presence of language in Neanderthals more parsimonious than assuming its absence. Finally, this case is arguably of global importance to linguistics at large, as it is one of the very few potential ‘windows’ on dating the beginnings of language. Linguistic literature, including introductory textbooks (see Section 3.3.1) will keep on making estimates of the anciency of language, speculative as they are. We believe that basing these estimates on state-of-the-art information is no less important than hedging them for speculativeness.

4.4.2 Cultural evolution

The second cluster of empirical results relevant to language evolution comes from modelling and experimental studies focussing on the cultural evolution of language (e.g. Kirby 2012; Tamariz and Kirby 2016; Tamariz 2017).⁶ This research is typically less concerned with the questions of the biological origin of the language faculty, but instead elucidates the emergence of meaning and structure in the linguistic code itself (see Section 4.3.2). This type of research now constitutes the core of empirical studies presented at Evolang conferences, but is virtually absent from linguistics textbooks.

Cultural evolution as a framework is particularly valuable, since it provides the most direct data on language evolution, and in particular on the evolutionary pressures shaping language structure. While comparative evidence from fields such as primatology or palaeoanthropological evidence from the hominin fossil record is necessarily indirect, the cultural evolution of communication can be studied in the laboratory, through experiments with human participants. As such, it represents a quintessentially hypothesis-testing approach, and the adoption of such methods to study the evolution of language was in a large part responsible for the change of profile of language evolution as a research field, from speculative to evidence and experiment based.

In stark contrast to its central role in current language evolution research, barring a single exception (McGregor, three references), the topic of the cultural evolution of language is absent from the introductory linguistic textbooks that we examined. This can be partly explained by the relative recency of cultural evolution as a research area (e.g. Richerson and Boyd 2005; Mesoudi et al. 2006), both in a general sense and with regard to its role in language origins and language change. However, from today’s perspective, the almost complete neglect of this topic in introductory linguistic textbooks should be seen as a major oversight. Cultural evolution deserves a better representation in textbooks, as it addresses many of the concerns that language evolution research lacks an experimental, predictive framework. Furthermore, it is not only relevant for the study of the evolutionary origins of language, but provides a set of experimental methods that can be used to study the emergence of semiotic systems (e.g. Galantucci et al. 2012, see Section 4.3.1). In addition, it can also be used to study the cultural change of languages more generally from an interdisciplinary perspective, in essence representing an analogue to the biologist’s Drosophila (cf. Roberts 2017). Integrating these research frameworks into discussions of language evolution in introductory textbooks is therefore likely to prove highly profitable.

5. Conclusion

In sum, in our examination of the most popular ‘introduction to linguistics’ textbooks, we found that the topic of language evolution and language origins is not prominently represented. Among the research areas that were most frequently mentioned were biological aspects of human evolution, references to extinct hominins, and discussions of the scepticism towards language evolution research. While animal communication is discussed much more frequently, textbooks also show wide variation in how much space they devote to the topic. Some of the most extensively covered topics include animal communicative behaviours, comparisons of animal versus human communication, and references to research with language-trained animals.

We found the factual accuracy to be good overall, with the most frequent mistake relating to the long-held belief that the vocal tract of non-human primates is incapable of producing speech sounds, which is understandable given that this is a relatively recent research development. However, the topics covered in our analysis are treated as a peripheral rather than core linguistic topic. We found the content on animal communication and in particular language origins and evolution to vary considerably between the textbooks, and this missing homogeneity is indicative of a lack of consensus on a canonical body of knowledge that students of linguistics should be expected to internalize. They also appear to be considered marginal, ‘luxury’ topics that are sometimes not covered at all or just in passing, especially in the shorter textbooks. An indicative example of this can be seen in O’Grady et al., where animal communication is relegated to an online-only chapter only accessible via subscription (cf. Section 3.1).

The most important conclusion of our study is that the representation of the topics covered in our analysis, and in particular the origins and evolution of language, does not reflect the state of the art. Furthermore, this problem appears to disproportionately concern the most influential textbooks as measured by their OS score (esp. Fromkin, Yule—see Section 1 and Table 1), whose consecutive editions to a large degree inherit their content and organization from previous editions, which favours only local instead of global changes.

We recommended amendments on several dimensions. First, the relatively extensive representation of non-scientific content such as myths, religious stories, and 19th-century ‘bow-wow’-type accounts to the detriment of presentations of modern language evolution research, which was perhaps merited several decades ago, is no longer tenable in the face of the wealth of currently available scientific content that informs language origins questions. Non-scientific motifs should be reduced to symbolic proportions that can be justified on the grounds of their historical importance as cultural codes, in favour of a better representation of contemporary accounts, debates, and evidence (see esp. Section 4.3.1). Second, several specific approaches or perspectives that are at the heart of current language evolution research are absent from linguistics textbooks, in particular signalling theory (Section 4.2.2) and cultural evolution (Section 4.3.2). Their inclusion would be highly beneficial to young adepts of linguistics, for whom it would be an early (and in many cases perhaps the only) opportunity to become aware of dynamically developing approaches to the study of language-related phenomena. Third, although abandoning the reliance on Hockett-type lists of design features would be neither feasible nor fully desirable, such lists should be redefined to accommodate the recent findings such as on the status of arbitrariness in language or the importance of concepts such as cooperativeness, domain generality and turn-taking (Sections 4.2 and 4.2.1).

One limitation of this study is that we only examined English-language textbooks published which, with the exception of Dirven and Verspoor (2004), were published in the USA and UK. For future studies, it would be interesting to see if this pattern is also apparent in introductory linguistics textbooks in other languages, which might come from different disciplinary and intellectual traditions.

Acknowledgements

We are grateful to Arkadiusz Jasiński, who helped develop an early version of this study. We would also like to thank the two anonymous reviewers as well as Dan Dediu for their insightful comments on the manuscript.

Funding

This research was supported by the Polish National Science Centre under grant agreement UMO-2019/34/E/HS2/00248. MP was supported by a postdoctoral fellowship from the University Centre of Excellence IMSErt: Interacting Minds, Societies, Environments, Nicolaus Copernicus University in Toruń.

Conflict of interest statement: The authors declare that there is no conflict of interest regarding the publication of this article.

Data Availability

The data underlying this article are available in OSF, at https://osf.io/5ta7x/

References–Textbooks

References

Footnotes