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.
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.
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.
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.
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.
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 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.
W. Tecumseh Fitch
This article presents the multiple uses of the concepts of “innate” and “instinctive”, by biologists. A broad notion of “innate” in the sense of “having some genetic basis” has thus been central to evolutionary approaches to behavior. Lorenz and other ethologists focused on the study of instinct for three practical reasons that include the fact that it justified the discussion and experimental investigation of the adaptive function of behavior, in a Darwinian context, and it allowed ethologists to construct phylogenetic taxonomies of behavior, and thus to explore the evolution of behavior using a comparative method. It signaled a research strategy focused on those aspects of behavior that appear reliably in a species by the time of study, but which avoided the difficult problem of their developmental origins. The developmental psychologist Daniel Lehrman noted that ethologists used the term “instinct” in multiple different ways. Lorenz and his colleague Niko Tinbergen argued that evolved innate mechanisms could not be avoided in understanding behavior, but that developmental, mechanistic, and evolutionary questions all have a role to play in ethology. Lorenz concluded that learning is impossible without inherited information, but he denied the opposite claim, which was that all instincts entail learning.
Bridget D. Samuels, Marc Hauser, and Cedric Boeckx
Do animals have Universal Grammar? The short answer must be ‘no.’ Otherwise, why do human children learn language with strikingly little conscious effort, while no other animal has even come close to approximating human language, even with extensive training or exposure to massive linguistic input? However, many of the cognitive capacities which clearly serve our linguistic ability—rich conceptual systems, vocal imitation, categorical perception, and so on—are shared with other species, including some of our closest living relatives. This suggests that the question is more complicated than it might first appear. In the present work, we use phonology as a case study to show what type of cross-species evidence may bear—now and in future work—on the issue of whether animals have various components of UG, which we construe here broadly as the systems that are recruited by language but need not be specific to it.
This article explains the emergence of the language faculty over the years. The organisms are complex and integrated so any adaptive change must automatically spin off structural by-products. Some properties are not selected for and are not accidental by-products, but they emerge because of deep, physical principles that affect much of life. They reflect limits on the kinds of things that evolution can make, and they arise through the interaction of physical principles. Physical laws describe the limits to evolutionary change, in the same way that principles of universal grammar (UG) prescribe the limits to grammatical change at the phenotypical level. The multifaceted approach to the evolution of the language faculty differs from the approach of people whom Gould called singularists. Singularists invoke just one factor to explain evolutionary development that is natural selection. The result of natural selection is adaptation, the shaping of an organism's form, function, and behavior to achieve enhanced reproductive success. Singularists suggest that selective forces shaped individual components of UG, such as the Subjacency Condition, which permits elements to move only locally. Modern Panglossians show that the Subjacency Condition constrains speakers to produce forms that can be understood in accordance with an individual's apparent parsing capacity.
Kathleen R. Gibson
This article gives an overview on the various brain structures, other than neocortex, contributing to speech and language. The regions of the avian brain which are considered functionally homologous to human neocortex, are nuclear, as opposed to cortical, in their cellular arrangements. The functional significance of nuclear versus cortical neuronal arrangements remains unknown. The intelligence is best measured by ratios that explicitly and/or implicitly discount other neural areas. The most extreme such measure is Dunbar's neocortical ratio that is the ratio of the size of the neocortex to the size of the entire remainder of the brain. The ratio, which is based on the explicit assumption that the neocortex is the primary seat of intelligence, also rests on the implicit assumption that enlargement of non-neocortical brain structures lowers intelligence. The nuclei and basal ganglia contain neurons that are arranged in a non-layered fashion. Such structures may also lie entirely within the brain, and thus have no visible representation on the outer brain surface. The cerebellar lesions can be associated with a much wider range of cognitive and sensory defects, including defects in working memory, procedural learning, syntax, word order, word choice, and autism. The deficits in both the basal ganglia and the cerebellum accompany the orofacial dyspraxia that results from FOXP2 mutations.
Robert M. Seyfarth and Dorothy L. Cheney
This article describes the primate social cognition as a precursor to language. The goal of phylogenetic reconstruction is to group similar animals together. One method of phylogenetic reconstruction is based on measures of distance, and arranges species into a phylogeny such that each is grouped with those with which it shares the greatest number of characters. Other methods rely on parsimony, generating the phylogeny that requires the fewest evolutionary changes in character states. Among primates, both methods yield a branching “tree structure” in which humans are grouped more closely with apes, less closely with Old World monkeys, and progressively less closely with New World monkeys, prosimians, and non-primate mammals. This phylogeny is consistent with both distance and parsimony such as morphological and genetic evidence to indicate both that there is less-evolutionary distance between humans and chimpanzees/bonobos than between humans and any other primate and also that a phylogeny that groups humans and chimpanzees/bonobos together is more parsimonious than a phylogeny that does not. Non-human primates use acoustically different vocalizations in different social contexts, suggesting that the mechanisms underlying call usage have a strong genetic component, although perhaps not as strong as the mechanisms underlying call production. The theory of mind spurred individuals not only to recognize other individuals' goals, intentions, and even knowledge as monkeys and apes already do but also to share their own goals, intentions, and knowledge with others. The evolution of a theory of mind thus spurred the evolution of words, grammar, and the vocal modifiability that these traits required.
A solution to the logical problem of language evolution: language as an adaptation to the human brain
Nick Chater and Morten H. Christiansen
This article addresses the logical problem of language evolution that arises from a conventional universal grammar (UG) perspective and investigates the biological and cognitive constraints that are considered when explaining the cultural evolution of language. The UG prespective states that language acquisition should not be viewed as a process of learning at all but it should be viewed as a process of growth, analogous to the growth of the arm or the liver. UG is intended to characterize a set of universal grammatical principles that hold across all languages. Language has the same status as other cultural products, such as styles of dress, art, music, social structure, moral codes, or patterns of religious beliefs. Language may be particularly central to culture and act as the primary vehicle through which much other cultural information is transmitted. The biological and cognitive constraints helps to determine which types of linguistic structure tend to be learned, processed, and hence transmitted from person to person, and from generation to generation. The communicative function of language is likely to shape language structure in relation to the thoughts that are transmitted and regarding the processes of pragmatic interpretation that people use to understand each other's behavior. A source of constraints derives from the nature of cognitive architecture, including learning, processing, and memory. The language processing involves generating and decoding regularities from highly complex sequential input, indicating a connection between general-purpose cognitive mechanisms for learning and processing sequential material, and the structure of natural language.
Vincent M. Janik
This article gives an account of vocal communication and cognition in cetaceans that comprise aquatic mammals. Cetacean communication occurs primarily in the acoustic domain. Light scattering and absorption leads to very limited visibility underwater while the sense of olfaction is virtually absent. The males of most baleen whale species produce long, elaborate song sequences during the breeding season. These appear to keep other males away and attract females. The song of the humpback whale has a hierarchical structure and is the most complex one among whale songs. It consists of phrases that are made up of multiple elements. The patterns of change in the song of humpback whales demonstrate clearly that these animals are capable of vocal learning, a relatively uncommon trait in mammals. All males in a population sing the same song at any one time, but the song of the population changes over the singing season. The bowhead whale has a simpler song but changes song in synchrony similarly to humpback whales. The songs of other baleen whales are much simpler and often consist of only one to three elements that are repeated in long song sequences. Bottlenose dolphins and several other dolphin species produce individually distinctive signature whistles that develop early in life. These can remain stable for at least a decade and, in the case of females, most likely for their entire lives. Signature whistle development is influenced by vocal learning, with dolphins copying and modifying aspects of other animals' whistles to develop their own unique frequency modulation pattern.