Are other animals as smart as great apes? Do others provide better models for the evolution of speech or language?
Kathleen R. Gibson
This article reviews recent evidence for advanced, language-pertinent, cognitive capacities in birds and mammals and evaluates the potential suitability of song and other animal vocal behaviors as models for the evolution of speech. Dolphins are extremely vocal, exhibit intelligence across a number of behavioral domains, are highly social, and often cooperate to herd schools of fish. Dolphins can also recognize themselves in mirrors, coordinate body postures and swimming patterns with those of other dolphins, and imitate each other's vocalizations, including unique signature whistles which serve for individual recognition among adults and in the mother-infant dyad. The only other non-primate mammals whose “language” capacities appear to have been investigated are domestic dogs. Some have also claimed that domestic dogs equal or exceed great apes in social intelligence. It is reported that both elephants and spotted hyenas are unusually intelligent. Elephants remember and recognize by olfactory and visual means numerous conspecifics and classify them into social groups. They also sometimes cooperate to achieve joint goals and seem to understand others' intentions and emotions. Elephants have highly manipulative trunks, use tools for varied purposes, may recognize themselves in mirrors, and may have a stronger numerical sense than non-human primates. They have elaborate vocal, olfactory, tactile, and gestural communication systems and can imitate some sounds.
This article provides an overview of bird song and language. There are several reasons why bird song might be of interest to those who are studying human language. First, and most obviously, it is a system of communication. Birds use sounds to communicate with one another. The most elaborate sounds are referred to as songs; males largely use songs in the breeding season to attract mates and keep rivals out of their territories. But there are other simpler sounds, usually labeled as calls, which fulfill other functions and are often used by both sexes throughout the year. Sounds can go round corners and are as useful by night as they are by day, both features that give them an advantage over visual signals. The third main modality, that of smell, has the advantage of persistence, as when the scent marks of one dog are sensed by another days later, but is certainly not appropriate for the transfer of a complex and changing stream of information. Beyond these two basic similarities comes a fourth, superficially more important, one: birds, like human beings, often have a huge repertoire of different sounds. To conclude, it is clear that vocal communication is of prime importance in many birds as it is in humans. Some of the similarities, such as that between our vocabulary and the large song repertoires found in many birds, are superficial. But the fact that learning plays a role in the song development of many birds, as it does in language development, may help us to look back in time and think about the reasons why this crucial evolutionary step took place on the way of language development.
Frederick L. Coolidge and Thomas Wynn
This article proposes the important prerequisites for indirect speech that includes at least four major cognitive factors, adequate phonological storage capacity, recursion, a full theory of mind, and executive functions. The phonological store subsystem is considered to play a critical role in language production and comprehension. Adults who have greater phonological storage capacity have also been found to score higher on verbal tests of intelligence and higher on measures of verbal fluency and they also do better on retroactive and proactive interference tasks. The phonological storage capacity represents a short-term memory ensemble that can be phylogenetically tracked to earlier homologues in hominin evolution and to current primate brain systems. The recursion is highly dependent upon the phonological storage capacity. The theory of mind refers to the ability to infer the thoughts, emotions, and intentions of others. The theory of mind also consists of four independent skills that include detection of the intentions of others, detection of eye-direction, shared attention, and the final component called the theory of mind module. The final component, whose onset in humans is thought to develop by the age of four, contains a complex set of social-cognitive rules, and combined with the other three components, creates the full-fledged, adult-like theory of mind. The specific executive function might be involved in the theory of mind.
Michael A. Arbib
This article mentions that a formal view of compositional semantics is helpful both for what it reveals about the structure of language and also for what it deletes, including context, the use of compositionality to index rather than define meaning, and the role of idioms. It also discusses how Construction Grammar (CG) allows one to incorporate idioms into a framework in which compositionality may sometimes use familiar sequences of words as atoms when the meanings of single words do not themselves contribute to the meaning of the whole. Schema Theory shows what is meant by embodied meaning, and the way it is embedded in social experience. Linguists working within CG, with its close relations to Cognitive Grammar, have teased out the rule-governed and productive linguistic behaviors specific to each family of constructions.
Kenny Smith and Simon Kirby
The productivity of language is subserved by two structural properties: language is recursive, which allows the creation of an infinite number of utterances, and language is compositional, which makes the interpretation of novel utterances possible. A potential explanation for the linkage between the functional properties of compositionality and the compositional structure of language is that this fit arose through cultural, rather than biological, evolution. In order to argue that the compositional structure of language is a product of cultural evolution, it is assumed that language is compositional, socially learned, and therefore culturally transmitted. A well-established solution to the problem of linkage in biological systems is that of evolution by natural selection: adaptation. Compositionality can be explained as a cultural adaptation by language to the problem of transmission through a learning bottleneck.
Primates communicate not only because they are biologically hardwired to do so, but also because they pursue specific goals during social interactions. This is well documented in the context of ape gestural signals, which have revealed a considerable degree of flexibility in interesting ways. In terms of vocal behavior, however, both monkeys and apes appear to be much less flexible, which raises important questions about how and why vocal flexibility evolved in the human lineage. The emerging picture is that, across the primate order, flexibility is widespread in call comprehension but largely restricted to humans in call production. Non-human primates, including the great apes, are curiously constrained by weak motor control over their vocal apparatus, resulting in limited vocal repertoires. A key transition in the evolutionary origins of language may have been when early humans began to interact with each other collaboratively. Another prediction is that, the species in which infants are exposed to competition over non-maternal caregivers should be more likely to exhibit elaborate vocal behavior than species in which their mothers raise infants only. Research on the communicative skills of other cooperative breeders, particularly communal breeders, may provide interesting empirical data to test this hypothesis.
John L. Locke
This article presents several factors related to the evolution of vocal and phonetic behaviors thus discussing the emergence of symbolization and reference. Evolutionary theories must identify the environmental changes that produced phenotypic variation and the modes of selection that reinforced certain of the variants, thereby increasing reproductive success, and they must specify the developmental stages in which these actions took place. The primary task of evolutionary theorists is to identify the environmental changes, and the responses to those changes, that edged our ancestors closer to the linguistic capacity possessed by modern humans. A new paradigm, evolutionary developmental linguistics (EDL), a naturalization of human language, is concerned with the evolution of developmental properties, processes, and stages that independently, or in concert with other environmental changes, facilitated the emergence of language in the species. Modern humans have four developmental stages that include infancy, childhood, juvenility, and adolescence. Much of the linguistically relevant phenotypic variation originated in ancestral infancies, with selection by parents occurring in this stage, and, with persistence of selected behaviors, in later stages by peers and others. Juvenility provides additional time for the brain growth and learning required for reproductive success in various species of mammals. The modification of juvenility would naturally increase phenotypic variability and offer new bases for selection at a time when greater independence and sexual maturity were rapidly approaching.
Joan L. Bybee
The article demonstrates many aspects of grammar that can be derived from domain-general cognitive processes, especially those of neuromotor automation, chunking, categorization, inference-making, and cross-modal association. Construction grammar posits a direct connection between the conventionalized constructions of a language and their meanings. All constructions have some specific lexical or grammatical material in them. Construction grammar emphasizes the interaction of the lexicon with the syntax. The domain-general processes involved in construction formation and use are sequential processing and categorization. Sequential processing or chunking is the process by which repeated sequences of experience (words or other events) come to be grouped together in memory as units that can be accessed directly. Categorization is necessary to the cognitive representations of constructions in several ways. First, categorization is necessary for the recognition that an element or sequence is the same as one previously experienced. Second, categorization is used to develop the schematic slots of constructions. Constructions are created through the repetition and thus conventionalization of useful sequences of elements and their meanings arise from associations with the context and implications that are present. The most pervasive process by which new constructions are created is grammaticalization, in which a new construction is created along with a new grammatical morpheme and the latter evolves from a lexical morpheme or combinations of grammatical and lexical morphemes.
Biolinguistics is a fairly broad research program that allow for the exploration of many avenues of research, including the formalist, functionalist, and nativist, and it insists on the uniqueness of the language faculty or alternatively, nativist about general (human) cognition, but not about language per se. It is assumed that the language faculty arose in Homo sapiens, and fairly recently, that is, within the last 200,000 years. The recent emergence of the language faculty is most compatible with the idea that at most one or two evolutionary innovations, combined with the cognitive resources available before the emergence of language, delivers the linguistic capacity much as it is known today. Biolinguists, especially those of a minimalist persuasion, have explored the possibility that some of the properties of language faculty may have emerged spontaneously, by the sheer force of biophysics. The type of principles by which minimalists seek to reanalyze the data captured by previous models are, quite plausibly, reflexes of computational laws that go well beyond the linguistic domain. All the linguistic models, no matter how minimalist, rely on the existence of lexical items. Numerous comparative studies in psychology reveal that mature linguistic creatures transcend many cognitive limits seen in animals and prelinguistic infants. Such limits are the signature limits of core knowledge systems, which correspond to primitive knowledge modules. Such systems suffer from informational encapsulation and quickly reach combinatorial limits.
The human hands, face, and vocal machinery have evolved as finely differentiated parts as compared to other primates due to the two phenomena that includes child development and computational modeling. Infants imitate face and hand action as well as speech. All three modalities may share a common evolutionary path to organ differentiation through imitation. Facial imitation is unique among the three because infants can neither see the face they feel nor feel the face they see, so that imitation must be mediated by an intermodal representation. Language, spoken or signed, evidently requires an integral anatomical system of discrete, independently activated parts that can be coordinated to effect rapid sequences of expressive global action. Consonants are specified by acoustic trajectories, formed by gestural combinations of varying degrees of complexity. Lindblom's proposed a modified dispersal algorithm to predict consonant-vowel (CV) syllable trajectories by means of a cost/benefit ratio (articulatory cost/perceptual discriminability) summed and minimized over a system of syllable trajectories such as might appear in a small lexicon. Lindblom's work offers the most comprehensive computational model so far available of how systems of discrete gestures, phonemes, and syllables may have emerged by self-organization under perceptuomotor constraints from an evolved vocal tract.
William D. Hopkins and Jacques Vauclair
This article reviews several studies on the behavioral and neuroanatomical asymmetries in non-human primates pertaining to the production of communicative behaviors. Hopkins and his team have reported population-level right-handedness for interspecies manual gestures associated with the request for food from a human. Meguerditchian and co-workers examined handedness for a variety of manual gestures during inter and intra-species communication in captive chimpanzees and found that the apes were significantly right-handed for all gesture types. Hauser reported that the left side of the face began to display facial expressions earlier than the right side for open-mouth threat and fear grimace in rhesus monkeys. Hauser and Akre examined the onset of mouth-opening asymmetries in rhesus monkeys during the production of several types of vocalizations. Hook-Costigan and Rogers showed that common marmosets displayed a larger left hemi-mouth during the production of fear expressions, including those that were or were not accompanied by a vocalization. Fernandez-Carriba with co-workers reported significant left orofacial asymmetries for several facial expressions including hooting, plays, silent-bared teeth, and scream face. Losin's team assessed orofacial asymmetries for four facial expressions associated with vocalizations in chimpanzees including hooting, food-barks, extended food grunts, and raspberries. Losin has found that food-barks and hoots were expressed more intensely on the left side of the face whereas extended food grunts and raspberries were expressed more intensely on the right side.
Irene M. Pepperberg
Most language evolution research focuses on primates, positing a hominin transitional link with emerging learned vocal communication. Such research increased after apes, humans' closest genetic relatives, learned elements of human communication systems. This article traces the evolution of language and communication with special reference to parrots and other songbirds. Grey parrots, despite considerable phylogenetic separation from humans, acquire comparable human-like communication skills and, unlike present-day apes, can imitate human speech because they can learn novel vocalizations. Specifically, they acquire species-specific and heterospecific vocalizations by actively matching their progressive production of specific sound patterns to live interacting models or memorized templates. Research on selective pressures resulting in avian vocal learning and imitation could provide clues about pressures leading to similar human skills. To understand the ancestral hominin condition, language evolution researchers might use models based on both phylogenetic kin and birds. Birds, although having diverged from the lineage leading to humans approximately 280 million years ago, can provide models for the evolution of vocal communication.
Grammaticalization theory has become an influential theory within historical linguistics. Grammaticalization is the process whereby open-class lexical items develop over time into closed-class items with grammatical functions. It is said to be a uniform series of semantic changes involving metaphorical usage such as spatial terms acquire temporal meanings but not vice versa and “bleaching”. Grammaticalization often leads to “morphologization”, which is an independent marker of tense or where a number becomes an affix rather than remaining a free wordform, and may even ultimately fuse with the root of the lexeme to which it is attached. It is always possible for grammaticalization to stop short of morphologization that applies to most of the languages of East Asia. Even without any syntax there could be phonological processes operating between regularly contiguous “words”, and some of these processes could in due course become opaque. This would give rise to situations where the same meaning was expressed by two or more forms in different contexts that is, to instances of synonymy. Even without syntax, some items could be regularly juxtaposed to express a consistent conventionalized meaning. The capacity for allomorphy and morphophonological alternation could have arisen alongside syntax or even before it, but at any rate independently of it.
Peter F. MacNeilage
This article focuses on the evolution of phonology over the years. The most comprehensive investigation of the innateness hypothesis in phonology is that undertaken by Mielke regarding the common claim that there is a small finite set of universal innate distinctive features that can describe the sound patterns participating in what are called phonological processes of all languages. He points out that the multiple sounds often participate in the same sound pattern. When a group of these sounds exhibits the same behavior it is often the case that these sounds are phonetically similar to each other. This type of grouping of sounds is termed a natural class. Syllabic “sonority” is considered to be an innate mental principle revealed by the fact that the loudest sound in a syllable is the vowel, and sonority then tends to decrease as the distance from the vowel of a preceding or a following consonant in the same syllable increases. The pattern can be attributable to peripheral biomechanics rather than mental structure. The concept of “markedness” is considered to involve another innate mental principle. The discipline of phonology has contributed an enormous amount of valuable information about the sound patterns of language.
Evolutionary biological foundations of the origin of language: the co‐evolution of language and brain
Szabolcs Számadó and Eörs Szathmáry
This article explains the evolution of human language and the brain. There are many ways organisms can adapt to moving targets. One of the ways is genetic evolution, when natural selection acts on variation in the population, selecting against those alleles that provide the least fit to the environment. The second way is by utilizing the phenotypic plasticity of a genotype. The third way is by means of systems and organs, which have evolved to cope with fast-changing environments and which have genetic underpinnings also. A set of genes can give rise to different phenotypes depending on the environment in which development takes place. The phenomenon, phenotypic plasticity, may be adaptive in species with variable environments. When natural selection acts to preserve adaptive phenotypes, it can lead to genetic change and to the fixation of specific phenotypes within a population by several evolutionary processes, including the Baldwin effect and genetic assimilation. The human brain is a very specific organ selected for the ability to track fast-changing parts of the relevant environment, which for hominins also included the linguistic environment. The human brain is highly efficient when it comes to language acquisition and production and is more efficient than any other known brain or artificial computing mechanisms.
This article deals with the evolution of natural languages and examines artificial or imaginary languages that supply material for evolutionary-linguistic thought-experiments. The term “creole” has been used in a variety of ways. One usage links its definition to that of “pidgin”. A pidgin language has been defined as a rudimentary language even if to some degree it is an institutionalized form of language used between speakers whose mother tongues are mutually incomprehensible. A creole is then a pidgin that has acquired native speakers such as children surrounded by adults that belong to different speech communities and therefore talk to each other most of the time in pidgin. One of the group of researchers compared human cognitive and communicative capacities with those of animals. They attempted to identify what is contained in the “faculty of language in the narrow sense” (FLN), that is, those characteristics or capacities that are both peculiar to humans and peculiar to language. They suggest that the FLN may turn out to be limited to a sole characteristic, namely recursion. The vocabulary of one of the languages, monocategoric, contains two classes of items that include “simple expressions”, such as snake, you, John, Mary, and story, and “operators”. Operators may be one-place, two-place, three-place or in principle n-place for any n > 0. A well-formed “expression” in monocategoric is any simple expression or any complex expression formed from one or more other expressions (whether simple or complex) followed by an appropriate operator.
Bernard A. Wood and Amy L. Bauernfeind
This article reviews the fossil evidence for human evolution from the earliest hominins to the emergence of Homo erectus. There are many differences between the hard-tissues of living modern humans and chimps/bonobos. Most researchers agree that the last common ancestor (LCA) of the hominin and panin clades was probably more likely to have been chimp/bonobo-like than modern human-like. The earliest members of the hominin clade would most likely have had smaller canine teeth, larger chewing teeth, and thicker lower jaws as compared to the earliest panins. There would also have been some changes in the skull and postcranial skeleton linked with more time spent upright and with a greater dependence on the hind limbs for bipedal walking. These changes would include a forward shift in the foramen magnum, wider hips, habitually more extended knees, and a narrower, more stable, foot. The group, possible hominins, includes Ardipithecus ramidus, Orrorin tugenensis, Sahelanthropus tchadensis, and Ardipithecus kadabba. The main differences between Ar. Kadabba and Ar. ramidus s. s. (sensu stricto) are that the upper canine crowns of the former have longer crests, and that the P3 crown outline of Ar. kadabba is more asymmetrical, and thus more ape-like, than that of Ar. Ramidus. Another group, archaic hominins, covers two genera, Australopithecus and Kenyanthropus. Australopithecus afarensis is the earliest hominin to have a comprehensive fossil record including a skull, several crania, many lower jaws, and sufficient limb bones to be able to estimate stature and body mass.
The adaptive success of organisms depends on the categorization that is the ability to do the right thing with the right kind of thing. Most species can learn categories by direct experience (induction) and only human beings can acquire categories by word of mouth (instruction). Language began when purposive miming became conventionalized into arbitrary sequences of shared category names describing and defining new categories via propositions. An individual must be able to distinguish the members from the non-members in order to categorize correctly. The feature detector for some categories is inborn. Most categories, however, have to be learned through trial and error during the lifetime of the organism. The artificial-life simulations have showed that simple virtual creatures in virtual worlds, which must learn to do the right thing with the right kind of thing in order to survive and reproduce, are able to categorize through trial-and-error experience. It can be done with the help of neural nets that are able to learn to detect the features, which reliably distinguish one category from another.
Karl C. Diller and Rebecca L. Cann
This article concentrates on the three genes of recent interest in the literature on language origins. These genes are microcephalin and ASPM, which cause microcephaly when disabled and FOXP2, which causes a severe speech and language disability when disrupted. The FOXP2 gene was isolated, sequenced, classified as a member of the forkhead box family, and named FOXP2 by the year 2001. The protein products of forkhead genes have forkhead DNA binding domains, which bind to specified regulatory sequences in other genes, and regulate the expression of these other genes. FOXP2 is expressed in the mouse brain during development, but is also expressed in a wide variety of mouse tissues. The gene has many essential roles in mammalian development and function that are totally unrelated to language. It was announced in the year 2005 that two genes essential for proper brain growth, microcephalin and ASPM, are undergoing a change. Microcephalin and ASPM proteins are crucial for proper brain development. Microcephalin is involved in regulating the cell cycle especially in relation to DNA repair before cell division. ASPM helps to align the mitotic spindles in the cell so that it divides symmetrically. The defective versions of microcephalin and ASPM result in microcephaly, a genetic disorder in which people have small heads and small brains.
This article focuses on the evolution of Homo and presents the origins of humanness. The earliest fossils assigned to the genus Homo come from Kenya, Ethiopia, Tanzania, and South Africa and are currently classified as Homo erectus. African Homo erectus fossils, the earliest dated to about 1.8 mya, include cranial, dental, and postcranial specimens, and the almost complete skeleton of an adolescent. Homo ergaster, a species distinct from the later-in-time Homo erectus fossil samples from Asia, has been proposed to accommodate early African fossils such as KNM-ER 3733. The increased brain size dramatically influenced cranial architecture during the course of human evolution. Skulls of later members of the genus Homo have an increasingly high and globular shape, with the maximum width of the skull, low and approximately at the level of the external ear canals as earlier described for Homo erectus, gradually moving higher on the vault, producing the strongly marked eminences on the parietal bones of modern humans. The development of stone tools allowed early Homo to exploit a greater range of habitats, eventually resulting in an expansion into Eurasia. The Dmanisi evidence includes at least four skulls, one with an associated mandible as well as other cranial and dental specimens, and stone tools similar to the Oldowan tools from East Africa. These fossils have some features similar to those of African Homo erectus and some similar to the transitional species Homo habilis.