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Home , Origin of language, Origin of speech

Opinion : A Changing Perspective Michael C. Corballis1,*

From ancient times, religion and philosophy have regarded language as a Trends faculty bestowed uniquely and suddenly on our own species, primarily as a From the Bible to Chomsky, language mode of thought with as a byproduct. This view persists among has been commonly viewed as repre- some scientists and linguists and is counter to the theory of evolution, which senting a profound change in thought, implies that the evolution of complex structures is incremental. I argue here that appearing suddenly and uniquely in , with communicative lan- language derives from mental processes with gradual evolutionary trajectories, guage as a byproduct. including the generative capacities to travel mentally in time and space and into Modern research increasingly sug- the of others. What may be distinctive in humans is the means to commu- gests mental continuity, more consis- nicate these mental experiences along with knowledge gained from them. tent with evolutionary theory, with nonhuman animals showing evidence for mental functions such as mental Is Language Uniquely ? time travel and theory of that are critical to communicative According to the Old Testament, language was a gift to Adam and was for a time the common language. language of all humans. When people built the so that they might reach closer to Heaven, the Lord thought them disrespectful and dispersed them, and confounded their Language can then be viewed as a so they could no longer communicate. Echoing this story has device for sharing thoughts and experiences rather than as a vehicle argued that language was bestowed on some individual, whom he whimsically Pro- for those mental contents themselves. metheus, within the past 100 000 , after sapiens is thought to have emerged as a distinct species [1]. Languages subsequently proliferated into the 6000 or so languages of the Nonhuman animals such as great apes world, the vast majority mutually incomprehensible. and dogs are more capable of under- standing human-like language than of producing it, so communicative lan- The notion that language emerged in humans well after our species itself evolved receives some guage in humans depended on adapt- support from , based on an apparent explosion of artistic and technological ing output systems to be flexible innovation within the past hundred millennia followed by dispersal from Africa in which H. enough to convey the generativity of thought. sapiens eventually replaced other large-brained hominins such as the and . Human artifacts from this period included art, musical instruments, , Such a system may have originated in bodily embellishments, and notations for record keeping and ended an apparent stasis in bodily before incorporating manufacture toward more innovative and varied forms. This surge of activity has been variously vocal signals that eventually provided us with . labeled the ‘human revolution’ [2], the ‘great leap forward’ [3], and the last of seven ‘major transitions in evolution’ [4] that began with the of replicating molecules. The paleoanthropologist Ian Tattersall writes ‘The entirely novel competitive entity represented by behaviorally modern Homo[258_TD$IF] sapiens appeared on the planet far too rapidly to be accounted for by the slow workings of at the individual level’ [5].

The Evolutionary Challenge Such views are antithetical to the theory of evolution. himself wrote ‘If it could be 1School of Psychology, University of demonstrated that any complex organ existed, which could not possibly have been formed by Auckland, Private Bag 92019, numerous, successive, slight modifications, my theory would absolutely break down. But I can Auckland 1142, New Zealand find no such case’ [6].

*Correspondence: Could language be the case that Darwin feared? Chomsky has often characterized language as [email protected] ‘an organ of the body’ and ‘on a par with the digestive and immune systems’ [7]. Language is (M.C. Corballis).

Trends in Cognitive Sciences, April 2017, Vol. 21, No. 4 http://dx.doi.org/10.1016/j.tics.2017.01.013 229 © 2017 Elsevier Ltd. All rights reserved. also undeniably complex, given that its rules of operation are still not well understood after some Glossary 60 years of Chomskian . The emergence of an organ as complex as language in a Evo–devo: derived from evolutionary single step seems clearly counter to Darwinian theory. developmental biology and incorporates the idea that regulatory genes, highly conserved across Modern Synthesis Evolutionary theory, however, has itself undergone changes, with the (see species, can influence embryonic Glossary) and the later Extended Evolutionary Synthesis incorporating ideas from genetics, development through varying the embryology, and population thinking, raising the possibility of more rapid change than that timing and expression of other implied by the selection of random mutations [8]. However, it remains problematic whether this genes. For example, although different species have dissimilar can drastically alter the Darwinian scenario, let alone explain the emergence of language in a limbs, such as legs, flippers, or single step. Pinker and Bloom discuss a number of neo-Darwinian possibilities including the wings, their development is view that language is a ‘spandrel’–a byproduct of the brain’s evolved capacity for computa- controlled by very similar genes, with tion [9] – but conclude that ‘there is every to believe that language has been shaped by the differences due to the way their “ ” “ ” expression is regulated. natural selection as it is understood within the orthodox synthetic or neo-Darwinian theory of Extended Evolutionary Synthesis: evolution’ [10]. Gould and Eldredge wrote of ‘punctuated evolution’, implying that evolution extensions of the Modern Synthesis, can proceed in spurts, but they were clear that it is ‘not about ecological catastrophe or sudden dating from the mid-20 century, genetic change’ [11]. Chomsky himself [1] appealed to evo–devo, whereby complex changes incorporating further developments in genetics, biology, and population can occur through mutations in regulatory genes that orchestrate the timing of development thinking; includes aspects such as rather than through the emergence of new genes. Such mutations, however, do not add evo–devo, punctuated evolution, complexity, suggesting they cannot explain the sudden emergence of a system as complex as spandrels, and . Modern Synthesis: early 20-century [12]. integration of Darwinian evolutionary theory with Mendelian inheritance Another prediction of the synthesis is that evolutionary change can be hastened through ‘niche and population-level ideas. construction’, whereby organisms modify their own environments, biasing the process of Niche construction: process by fl which organisms construct their own selection [8]. This might have in uenced and perhaps accelerated evolutionary change during environment, which can then alter the , which saw the emergence of what has been termed the ‘cognitive niche’ [13], the selection of traits that are but this would imply a gestation period of some 2 million years rather than a sudden change adaptive. For example, traits adapted – within the past 100 000 years. Some have also contested the archeological evidence for the for survival in a hunter gatherer ‘ ’ society may differ from those human revolution , suggesting either that the changes were continuous and date back to adaptive in city life. precursors of H. sapiens [14] or that the impression of change was more a question of sporadic Punctuated evolution: the idea that regional variation than of discontinuity through time [15]. new species evolve relatively rapidly followed by a period of stasis with little genetic change. Spandrel: an architectural term A common theme among those who argue for the sudden emergence of language is that referring to the triangular space it signaled a change in the manner of thought itself. Thus, Tattersall writes that from about between an arch, a pillar, and a 100 000 years ago ‘we start finding plausible indications that members of the new species were ceiling that is sometimes appropriated by artists for added ’ ‘ ’ starting to think symbolically [5]. Chomsky writes of internal language (I-language) as the decoration. The term is borrowed in fundamental basis of human symbolic thought with communication merely a byproduct [1,7].It biology to refer to a byproduct of a is, then, through a secondary process of ‘externalization’ that the diverse languages, spoken that evolved for different . A simple example is the use and signed, are formed. I-language is considered common to all humans, underlying what of the nose to hold spectacles. The Chomsky calls ‘’–a term that goes back to 17th-century scholars who brain has been claimed to provide a sought to identify aspects of language common to all languages [16]. There have been many rich source of spandrels, with attempts to specify such a grammar, once satirized by James D. McCawley in his book Thirty activities such as music or chess ’ perhaps being byproducts of a Million Theories of Grammar [17], but Chomsky s most recent and most economical account is computational faculty selected for the [18]. The main ingredient is ‘unbounded ’, whereby elements are other adaptive functions. merged recursively to generate a potential infinity of structures.

The burden of explaining language evolution is lessened, however, if language is regarded as communication, not thought. In this case thought can be considered to have precursors in nonhuman animals (e.g., [16,19]) rather than to have appeared in a single step in H. sapiens. Language can then be considered primarily as a device for sharing our thoughts and expe- riences – more a tool than a fundamental cognitive shift [20,21]. In moving the emphasis to language as communication rather than thought, this more commonsense view, in the of

230 Trends in Cognitive Sciences, April 2017, Vol. 21, No. 4 Dor, ‘turns the Chomsky proposal on its head’ [21]. The ‘great leap forward’, if indeed a reality, can then be attributed to an enhanced capacity to share knowledge and experience rather than the thoughts themselves.

This is not to say that thought is independent of language. Indeed, many if not most of our thoughts and knowledge are derived from what other people tell us. However, thoughts themselves, whether derived from personal experience or from communication with others, are not the same as the language in which they are expressed. We often cannot find words for particular thoughts we have or for individuals we can envisage although their names escape us. Thought cannot be tied to any specific language, and when we translate from one language to another the thought remains – at least ideally – despite being expressed in different words [22]. Even in retelling stories within the same language, we typically do not use the same words or expressions. As a source of knowledge, however, language creates a ratchet effect so that knowledge can build over time and spread among individuals, allowing specializations to develop [4]. In these ways language may have been influential in a human revolution, but through its power of communication rather than from a change in the innate structure of thought itself.

If expressive language is designed for the communication of thought, its properties must be at least partly shaped by the way in which thought itself is structured. In this respect the account to be given here is in accord with Chomsky’s. The difference lies in the suggestion here that the nature and structure of thought have a long and gradual evolutionary history.

Several authors have speculated about possible precursors of language, including the manu- facture and use of [23,24], navigation [25,26], [27], and social understanding [28]. Here I focus on two mental capacities that seem especially critical to the recursive, generative nature of language itself and that may ultimately obviate the need for any special mechanism unique to language, or indeed to our own species.

Mental Time Travel ‘Displacement’ is a design feature of language enabling reference to events at other places and other times, past or future [29], and is increasingly recognized as critical to its evolution (e.g., [30,31]). This in turn must depend on the ability to imagine such events, such as what you did yesterday or plan to do tomorrow. Although some, including myself, have claimed that mental time travel itself is uniquely human [32,33], the evidence increasingly suggests that it may have a long evolutionary pedigree, with behavioral evidence from species as disparate as scrub jays [34], rats [35], and [36,37]. Behavioral evidence, however, can be ambiguous or flawed [38], and my own shift to an acceptance of evolutionary continuity was prompted mainly by evidence from neuroscience [39].

It is well established that the hippocampus in humans is activated when people consciously remember past episodes or imagine future ones [40,41] or even imagine purely fictitious ones [42]. In the rat, ‘place cells’ in the hippocampus record where the animal is located in a spatial environment [43] and sometimes trace out trajectories even when the animal has been removed. The trajectories are sometimes ‘replays’ of trajectories previously taken, sometimes the reverse of those trajectories [44], and sometimes trajectories the animal did not take [45], some of which may be anticipations of future trajectories [46]. Reviewing this evidence, Moser, Rowland, and Moser write that ‘the replay phenomenon may support “mental time travel” . . . through the spatial map, both forward and backward in time’ [47]. Mental travels through known spatial locations may be a common capacity of animals that move about physically in space and need to know whether they are, where they have been, and where they might go next.

Trends in Cognitive Sciences, April 2017, Vol. 21, No. 4 231 In humans the hippocampus seems to be involved in language itself [48,49]. Even in the rat, however, hippocampal activity has some language-like properties. It is influenced by activity in the neighboring entorhinal cortex in a modular fashion, adjusting for parameters like spatial scale, direction of the head, and proximity to borders. Different combinations of modules can result in thousands of combinations, comparable to ‘that of an alphabet in which all words of a language can be generated by combining only 30 letters or less’ [47]. In short, spatial imagination, like language, is generative. I can imagine myself in different locations, such as my office, in many different ways and at different spatial scales. I can zoom out from the office to its location in the house, the location of the house in the city, the city in the country, and so on. Even in the rat, the spatial scale zooms out as recording shifts from the rearward to the forward end of the hippocampus [50] and this arrangement is mirrored in human hippocampal activity as people process narratives linked to videos, with increasingly forward activation as the focus shifts from detail to more global understanding [51].

Generative grammar itself, then, may depend on the generative nature of spatiotemporal imagination rather than on any property unique to language itself. The zooming property implies , in which spatial maps are nested in maps at larger scales. It has even been proposed that Chomsky’s Minimalist Program and the concept of Merge can be applied to simple sensorimotor actions such as grasping and manipulating an [52]. We are profoundly spatial creatures and even our non-spatial thoughts, such as reasoning and logic, may be grounded in spatial rather than abstract [53]. The concept of universal grammar has been doubted [54,55], but if it can be said to exist its universality may reside in the common experience of the spatiotemporal world rather than in the innate structure of language.

Theory of Mind We travel mentally not only in time and space but also into the minds of others. The capacity to understand what others feel, think, or believe is known as and underlies the human obsession with storytelling, whether in the form of novels, plays, movies, TV soaps, gossip, or, in earlier times – and among present-day African tribes – stories told around the campfire at night [56]. It has been suggested that storytelling drove the evolution of language itself [57].

Theory of mind is required for language in a capacity other than storytelling. Language is not merely a matter of words; it requires that the speaker and listener (or signer) know what is in each other’s mind and that each knows that the other knows this – requiring metacognition [58,59]. In this sense language is underdetermined [60]. Even individual words may carry multiple meanings depending on context. An extreme example is the English ‘set’, which, according to the Chambers Dictionary, has 105 different meanings.

Whether nonhuman species possess theory of mind has been much disputed since Premack and Woodruff in 1978 asked ‘Does the have a theory of mind?’ [61] Thirty years later there was still disagreement; in one view, the answer was negative and the very idea that chimpanzees might have theory of mind was deemed ‘Darwin’smistake’ [62], while others found evidence that chimpanzees could be shown to understanding the goals, intentions, perceptions, and knowledge of others but not their beliefs or desires [63]. A more recent study, however, showed that great apes look in anticipation of where a human agent will falsely believe an object has been hidden [64] – they seem to pass the false-belief test, often regarded as the gold-standard test of theory of mind [65].Thisstudy joins a chorus of studies gradually showing greater mental continuity between humans and other species than is commonly assumed. Even rhesus monkeys may be capable of spontaneous metacognition [66].

232 Trends in Cognitive Sciences, April 2017, Vol. 21, No. 4 A neural network for mental orientation in ‘space, time, and person’ is now fairly well established in humans and includes widespread regions in the frontal, parietal, and temporal cortices [67]. This network overlaps extensively with what has been termed the ‘default mode network’, which is active in ‘mind wandering’–spontaneous internal activity unrelated to the concerns of the moment [68]. Homologous networks have been identified in monkeys [69] and rats [70], again suggesting evolutionary continuity. Of course, internal thinking may be less complex in rats and monkeys than in humans, but we should bear in mind Darwin’s edict: ‘The difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind’ [71].

In summary, comparative research is increasingly drawn to the conclusion that some nonhuman animals are capable of more ‘advanced’ cognition than hitherto realized, suggesting evolutionary continuity rather than a sudden shift in cognition that somehow made humans special. Mental excursions in time and space and into the minds of others may be more comprehensive and sophisticated in humans than in other species in part because of communicative language itself, which feeds our mental travels through storytelling and our minds through the exchange of knowledge. Their origins, however, may go well back in our evolutionary history.

The Communicative Aspect According to a shifting tide of opinion, it is in our ability to communicate our thoughts, rather than our thoughts themselves, that we differ most profoundly from other species and it is our

Box 1. The Gestural Origins Among only humans appear capable of [77] and therefore of speech. Language, however, is not restricted to speech; sign languages have all the hallmarks of true language [78]. This raises the possibility that language originated, not from vocal calls, but from manual . This idea goes back to the 18th century [79–81] and has been increasingly endorsed over the past few decades (e.g., [82–90]).

Captive great apes have never developed anything resembling speech but have learned to use manual gestures [72,91] in ways that have language-like features; great apes in the wild also communicate bodily in ways that are more language-like than their vocalizations [92]. People, too, gesture manually while speaking [93,94], and like speech, gesture involves the hippocampus [95]. Some have supposed that visible gesture and vocal language have always been equal partners [96,97] (but see [98] for a contrary view).

Gestural communication may derive from the ‘ system’, a brain circuit active during both the production and the perception of intentional movements, suggesting a natural basis for communication [85]. In macaques the system responds to actions perceived acoustically as well as visually but not to animal calls, implying that the incorporation of vocal action evolved relatively late [99]. Brain imaging of a homologous system in humans suggests that it expanded to encompass the language circuit [100].

Bodily actions provide a natural basis for relaying events in our predominantly spatial world, especially through hand and arm movements as exemplified in sign languages. During the Pleistocene, with the emergence of the genus Homo, brain size increased and the hands were increasingly freed by the shift to obligate , allowing communication through gesture and mime [101]. In the interests of efficiency, mimed gestures were probably simplified and con- ventionalized over time, losing their iconic quality [102]. Tomasello writes that human language might have ‘evolved quite a long way in the service of gestural communication alone, and the vocal capacity is actually a very recent overlay’ [89].

To some, a transition from the visible to the acoustic mode seems too extreme to be credible (e.g., [103,104]). Speech, however, is itself a system of gestures of the , , and [105]. Movements of the hand and mouth are linked neurally, phylogenetically, developmentally, and behaviorally [106–109], suggesting that mouth gestures might plausibly have blended into manual ones [110], and the visible movements of speech remain verbally informative [111], although adding vocalization makes the gestural content more accessible as audible speech. The acoustic code, however, is more arbitrary and is sustained largely through , although it does carry non-arbitrary associations [112,113].

The transition might be an early example of miniaturization À tucking the burden of communication into the mouth and freeing the hands and arms for activities such as carrying or making and using tools. It was perhaps this switch, and not language itself, that produced the ‘human revolution’ [114], but it did not stop there. Subsequent shifts, from writing to the Internet, have profoundly shaped and widened human culture.

Trends in Cognitive Sciences, April 2017, Vol. 21, No. 4 233 capacity to communicate that gives an inflated view of human cognition. The difference has Outstanding Questions more to do with production than with understanding. Great apes [72] and even dogs [73,74] Can we identify aspects of thought that can understand and respond to spoken requests involving sequential processing and are present only in humans and that [259_TD$IF] have no counterparts in nonhuman substantial word , which implies a degree of symbolic understanding but a lack animals? of the means to produce anything approaching human productive language. Great apes, at least, may come closer through bodily movement and gesture than through vocalization (Box 1). If so, can we find evidence that such aspects evolved suddenly within the The pressure to develop output systems flexible enough to communicate our thoughts and time span of Homo sapiens or is it more plausible to suppose that they experiences probably grew during the Pleistocene when our hominin forebears were evolved more gradually, such as during increasingly forced from a forested environment to more open territory with dangerous the Pleistocene? predators, and survival depended on cooperation and social interaction – the aforemen- tioned ‘cognitive niche’ [13]. The initial impetus may have come from the sharing of Can we find anatomical, genetic, or episodic events, whether remembered, planned, or fictitious but perhaps also increasingly fossil evidence that bears on the ori- gins of speech as distinct from lan- including information about territory, danger, food sources, tool making, and the habits and guage itself? abilities of individuals. Its course of evolution is probably best indexed by the threefold increase in brain size that began some 2 million years ago and is probably attributable to Or does the evidence further support the emergence of grammatical language [75] and the vast increase in knowledge that it the origins of expressive language in afforded. The increase in brain size was incremental through this period, again suggesting manual gestures rather than vocal calls? gradual evolution rather than the sudden appearance of a prodigious Prometheus within the past 100 000 years.

Concluding Remarks: Is Rapprochement Possible? There are some signs that the longstanding divide over language evolution may be softening. Through progressive modifications, Chomsky’s theory of has become simpler. This is suggested in the title of the current Minimalist Program, whose primary ingredient is Merge, recently described as the ‘simplest case’, requiring a ‘slight mutation’ producing a ‘slight rewiring of the brain’ [7]. These descriptions now seem at odds with earlier notions of language as a bodily organ producing a major transition in evolution and are perhaps an attempt to bring the evolution of language within the bounds of evolutionary credibility.

At the same time, Minimalist theory seems to place a greater burden on externalization to explain how a concept as apparently simple as Merge can account for the complex and varied among the 6000 or so languages, spoken or signed, in the world. A recent article points out that the parsing of a sentence cannot be based simply on the string of words or signs but must depend on an internal device to impose hierarchical structure; in its simplest form, that device is Merge, applied recursively. The question then is whether this internal structuring is ‘uniquely human (species-specific) and uniquely linguistic (domain-specific)’ [76] or whether it depends on the way that experience and knowledge have been incrementally structured over millions of years of evolution (see Outstanding Questions).

Acknowledgments Three unnamed reviewers provided extremely helpful input.

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236 Trends in Cognitive Sciences, April 2017, Vol. 21, No. 4

Letter

reverse-engineering style from this single from watching Swan Lake. In the same

functional perspective. Artful kinesthetics way, linguists now know with near surgi-

What is Language

of human skeletal structures in motion, cal-precision how the sentence ‘skeletal

and How Could it aka ‘dance’, also communicates, but structure’ generally fixes meaning. We

one would be hard pressed to derive know how ‘communication’ in the sense

Have Evolved?

the evolutionary history of the human tibia of transfer of propositional meaning is

1

Martin B.H. Everaert,

1

Marinus A.C. Huybregts,

2,3 Box 1. Structure Connecting Sound and Meaning

Robert C. Berwick,

4 Language is structured at all levels: (sound structure), (word structure), and syntax

Noam Chomsky, (phrase structure). The examples below show how structures built by the computational system are

5 6

systematically mapped onto sound and meaning.

Ian Tattersall, Andrea Moro,

7,8,

and Johan J. Bolhuis *

The two ways of pronouncing the string ‘white board eraser’, also reflected in spelling, are paired with a

difference in their meaning: (i) whíteboard eraser: an eraser for whiteboards; and (ii) white bóard eraser: an

Unraveling the evolution of human lan- eraser that is white.

guage is no small enterprise. One could

The eraser in (i) itself could have any color, but in (ii) it has to be white. Both meanings and stress patterns are

start digging somewhere in the largely

systematically derived from the structural patterns given in Figure IA,B, respectively.

unobservable past, working forwards to

the present, hoping to surface in the right

In Figure IA, the adjective ‘white’ first merges with the noun ‘board’ and constructs the compound

spot. Alternatively, one could start with

‘whiteboard’, which, as a unit, is merged with the noun ‘eraser’, yielding a bigger compound, an eraser,

the currently observed and well-estab- erasing what is written on whiteboards. When pronounced, the structure gives rise to the stress pattern

[whíteboard eraser].

lished properties of human language,

the phenotype of language, and work

In Figure IB, ‘board’ first merges with ‘eraser’, producing the nominal compound ‘board eraser’, which, as a

backwards, with these ‘knowns’ guiding

unit, is merged, in syntax, with the adjective ‘white’, yielding a nominal phrase, a board eraser that has a

the search for otherwise speculative his- white color. When articulated (in speech), the structure gives rise to the stress pattern [white bóard eraser].

torical ‘unknowns’. In a recent issue of

Trends in Cognitive Sciences, Corballis

(A)

[1] appears confident that only the first

strategy will serve. Evolutionary explana-

tions necessarily are historical, but few N

evolutionary biologists faced with such

a paucity of historical evidence would Ns Nw

forge ahead without first defining what, eraser

exactly, the phenotype is that ultimately As Nw

evolved [2]. Yet, Corballis criticizes what white board

we actually know about the human lan-

guage phenotype, because it does not

conform to his speculations [3]. We

believe that Corballis’ odd research inver-

sion suffers from misconceptions regard-

ing what we know about both language (B)

and evolution.

NP

The Nature of the Human

Aw Ns

Language Phenotype (Is Not white Communication)

Ns Nw

There is no denying that language is

board eraser

sometimes used to communicate, like

this Letter. However, this should not lead

to the apparently common fallacy that the Figure I. Nominal compound (A) versus nominal phrase (B). Abbreviations: A, adjective; N, noun; s,

strong; w, weak.

design of language can be inferred

Trends in Cognitive Sciences, August 2017, Vol. 21, No. 8 569

facilitated by language: our manipulation is merely idle verbiage. There is not even a information processing until after anatom-

of meaning is systematic and relies “on an remote connection between the two. If ical Homo sapiens had come on the

ingrained ability to recognize structure in someone were to say that the waggle scene some 200 000 years ago: a fact

language.” [4]. Meaning builds on a dance of the honeybee ‘may’ depend that Corballis mentions, but whose rele-

computational system that is sensitive on the laws of motion, no one would vance is left undiscussed.

to structural factors leading to hierarchical pay attention. A recent comparative study

structure (Box 1). All this has been over- of cross-species generative systems

Mental Time Travel

looked by Corballis. asserts that nonhuman animals have

Corballis also refers to, but regrettably

nothing resembling human recursive syn-

does not discuss, the position that “No

‘Language’ reduced to a mode of com- tax [7]. While many animal species recog-

other organism, instantaneously and

munication becomes vacuous as an nize statistical-probabilistic sequences,

effortlessly extricates from the environ-

explanatory motivation. Bees communi- linear associations, or even algebraic

ment language-relevant data, and in a

cate with flowers, your router communi- rules, only humans appear capable of

rather comparable way quickly attains

cates with your computer, we internalizing generative algorithms. In line

rich , again a feat

communicate via oil on canvas, and so with his view on ‘spatiotemporal imagina-

utterly beyond other organisms even in its

on [5]. The Corballian world of communi- tion’, Corballis appears to assume that

rudimentary aspects.” [12]. Corballis

cation is so diffuse that it becomes all the language inherits these sorts of property

attributes these achievements to mental

more puzzling why “the emergence of an from similarly structured actions. Such an

time travel (MTT) and Theory of Mind

organ as complex as language” would approach, linking recursion to observa-

(ToM), although, as frequently noted, both

apparently be limited to humans. tions from interactive language use, how-

of these competences are often dissoci-

ever, fails [8]. Moro has shown that the

ated from language ability: “autistic chil-

superficial parallels here between action

dren highly defective in theory of mind

Structured Thought sequences and sentences are misguided,

[ . . . ] can acquire rich linguistic compe-

Corballis claims thought is structured, again essentially backwards [9,10]. Self-

tence (and in fact a great deal of language

“

and that the nature and structure of reference, a defining property of recur-

acquisition proceeds before a

thought have a long and gradual evolu- sion, appears to be absent from the

shows any sign of having attained theory

”

tionary history , suggesting that, on this domain of motor action and spatiotempo-

of mind).” [12]. Significantly, again, no

point, he is in agreement with the position

ral imagination of nested maps [7], yet a

mechanism is suggested to lead from

advocated by Berwick and Chomsky [3]. rich part of human language.

ToM to the specific structures of lan-

However, all examples we know point to

guage. Worse, there is no discussion of

thought structured by syntax, not the

The Nature of Evolution

what the mechanisms of recursive

reverse. The hierarchical structure built

We are surprised that Corballis sub-

thought in MTT or ToM are, or how they

by the brain when processing sentences

scribes to the view that anything other

lead to the feat that has to be explained.

feeds our conceptual apparatus. Conse-

than an ancient and gradual origin for

Shifting the burden from recursive lan-

quently, language is basically a thought-

language “is counter to the theory of evo-

guage to recursive thought in MTT and

expressing tool [3,6]. For Corballis,

lution”, for he is clearly aware that our

ToM appears to us to leave the problem

‘thought’ permeates the entire animal

understanding of evolutionary mecha-

exactly where it was, adding nothing.

kingdom. That may be so, but he fails

nisms has been refined considerably over

to give any clue as to what he might mean

the past 150 years. Certainly, evolutionary 1

Utrecht Institute of Linguistics, Utrecht University, 3512

‘ ’

by this expansive notion of thought , how

change requires transitions from one via- JK Utrecht, The Netherlands

2

Department of Electrical Engineering and Computer

we could find out how ants, or songbirds

ble state to another, but this does not

Science, Massachusetts Institute of Technology,

‘think’, and why, in this view, “expressive

entail that phenotypic steps are necessar-

Cambridge, MA 02139, USA

3

”

language would take millions of years to

ily the tiny and incremental ones he favors. Department of Brain and Cognitive Sciences,

appear. Massachusetts Institute of Technology, Cambridge, MA

It is also unclear why he believes that

02139, USA

changes in gene regulation cannot “add 4

Department of Linguistics and Philosophy,

complexity”, especially when it is almost Massachusetts Institute of Technology, Cambridge, MA

Recursion 02139, USA

fi

certainly the case that modi cations at 5

American Museum of Natural History, New York, NY

Corballis suggests that “generative gram-

this level gave rise to the anatomically

10024-5192, USA

mar may [our emphasis] depend on the 6

distinctive species Homo sapiens [11]. School of Advanced Studies - Instituto Universitario di

generative nature of spatiotemporal imag- Studi Superiori, Pavia 27100, Italy

Furthermore, the archeological record 7

Cognitive Neurobiology and Helmholtz Institute,

ination, rather than on any property

contains no evidence of behaviors com-

Department of Psychology, Utrecht University, 3584 CH

unique to language itself.” However, this

patible with the style of linguistic Utrecht, The Netherlands

570 Trends in Cognitive Sciences, August 2017, Vol. 21, No. 8

8

Department of Zoology and St Catharine’s College,

thought emerging gradually according extractor [8]. Hierarchical structures

University of Cambridge, Cambridge CB2 3EJ, UK

to neo-Darwinian principles. may well be part of the cognitive appara-

*Correspondence: [email protected] (J.J. Bolhuis). tus by which humans and animals parse

http://dx.doi.org/10.1016/j.tics.2017.05.007 Everaert et al. suggest there ‘isn’t even a the world, and can exist in the absence of

remote connection’ between spatiotem- any means to communicate them. Seek-

References

poral imagination and grammar. There is ing analogs of human cognition does not

1. Corballis, M.C. (2017) Language evolution: a changing

–

perspective. Trends Cogn. Sci. 21, 229 236 nevertheless a growing understanding imply digging into the past and moving

2. Everaert, M.B.H. et al. (2015) Structures, not strings: lin-

that language evolved primarily as a forwards, ‘hoping to land in the right

guistics as part of the cognitive sciences. Trends Cogn.

’

Sci. 19, 729–743 means of communicating about the non- spot , as Everaert et al. suggest [2]; rather

3. Berwick, R.C. and Chomsky, N. (2016) Why Only Us: present, with the property of displace- it takes what we know about language

Language and Evolution, MIT Press

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7. Hauser, M.D. and Watumull, J. (2016) The Universal Gen-

erative Faculty: the source of our expressive power in not language, and the human system has appear’ [2]. The extraction techniques

language, mathematics, morality, and music. J. Neuroling.

certainly gained in complexity [5], but lan- used by the crows provide an example

Published online November, 9, 2016. http://dx.doi.org/

10.1016/j.jneuroling.2016.10.005 guage may well have evolved primarily as of a window into the nonhuman mind.

8. Legate, J.A. et al. (2014) Recursive misrepresentations:

a means to express them. There are others, a few of which are men-

reply to Levinson (2013). Language 90, 515–528

tioned in my article. Moreover, the actions

9. Moro, A. (2014) On the similarity between syntax and

–

actions. Trends Cogn. Sci. 18, 109 110 Theory of mind is also critical to the com- of the crows might themselves be con-

10. Moro, A. (2014) Response to Pulvermueller: the syntax of

municative aspect of language. As Chom- sidered communicative, perhaps to be

actions and other . Trends Cogn. Sci. 18, 221

sky once wrote, ‘Communication relies on copied by a watching bird. Expression

11. Tattersall, I. (2012) Masters of the Planet, Palgrave

Macmillan largely shared cognoscitive [sic] powers might then begin with overt behavior,

12. Chomsky, N. (2015) Some core contested concepts. J.

. . . ’ [6]. Gilles Fauconnier elaborates: gradually becoming decoupled and con-

Psycholing. Res. 44, 91–104

ventionalized, especially in social species

When we engage in any language

where survival depends on effective com-

activity, we draw unconsciously on

Letter vast cognitive and cultural resources, munication transcending time and space.

call up models and frames, set up Thus, the emergence of expressive com-

multiple connections, coordinate large

Leaps of Faith: A munication can itself be considered a

arrays of information, and engage in

gradual process, as in the gestural theory

Reply to Everaert creative mappings, transfers, and

of language origins I outlined [1].

elaborations [7].

et al.

Such resources go well beyond ‘I-lan-

1, On Evolution

guage’, and it is difficult to believe they

*

Michael C. Corballis As for evolution, even Tattersall seems

surfaced in a single step late in the evo-

bemused by the idea that the mind could

lution of our species.

In their comments on my Opinion in TiCS

have changed so dramatically in such a

[1], Everaert and colleagues [2] make sev-

short window of time. In a book cited by

eral leaps concerning the evolution of lan- On Erasers and Sticks

Everaert et al., he wrote:

guage, including the idea that language What of the distinction between a white-

‘It is a qualitative leap in cognitive state

implies a mental structure unique to board eraser and a white board eraser?

unparalleled in history. Indeed . . .

humans, and that this came about Analogous distinctions do appear to arise

the only reason we have for believing

‘

through an evolutionary great leap for- in nonhuman animals. New Caledonian that such a leap could ever have been

ward’ within our limited time span. crows can use a short stick to extract a made, is that it was made. And it

seems to have been made well after

Against this backdrop, perspectives on longer stick from a barred cage, and use

the acquisition by our species of its

language evolution have changed over this longer stick to extract food from a

distinctive modern form’ [9].

the past few decades, with language long tube, and do so immediately and

fi

increasingly regarded as a device for spontaneously. Therefore, they might be This sounds more like at than fact. Was

communicating thought rather than as said to know the distinction between a Homo sapiens was really so distinctive?

thought itself, with the structure of long-stick extractor and a long stick Evidence of mating between early sapiens

Trends in Cognitive Sciences, August 2017, Vol. 21, No. 8 571

and both Neanderthals and Denisovans leading, as Darwin put it, to differences of A new study by Parkinson and colleagues

even raises the question of whether sapi- degree, but not of kind. [12] is one of the first to shed light on how

ens was a species distinct from these the brain encodes the dense structure of

other large-brained hominins, uniquely 1 its social network. Whereas previous

School of Psychology, University of Auckland, Private

capable of language [10]. Perspectives Bag 92019, Auckland 1142, New Zealand work focused primarily on indexing pop-

are indeed changing. As two recent com- ularity [2], this study used an innovative

*Correspondence:

mentators put it: approach for measuring multiple addi-

[email protected] (M.C. Corballis).

http://dx.doi.org/10.1016/j.tics.2017.05.006 tional dimensions in a large sample, effec-

‘myth of a “modern human revolution”

tively capturing a more holistic picture of

is now rejected by archaeologists,

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’

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The Modern Synthesis does offer a more

study, in which they passively viewed vid-

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–

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novo in a single step. Spotlight

neuronal populations were encoding

social information, a more effective

Nevertheless, such a case would still

How Does Social

method for inferring mental states. This

smack of special pleading. Everaert and

fi

is because RSA capitalizes on ne-

colleagues appear secure in the belief that Network Position

grained spatial pattern differences, rather the nonhuman mind is unstructured.

Influence Prosocial

than on the overall activation of specific

However, absence of evidence is not

brain regions. What the authors observed

evidence of absence, and there are now Behavior?

was that a distributed network of separate signs from behavior or neurophysiology

1,

regions encodes each dimension of the

that the animal mind is indeed structured. Oriel FeldmanHall *

social network: social distance was

Moreover, our common ancestry with our Consider the sheer number of people you

indexed by the inferior parietal lobule

nearest nonhuman great-ape relatives interact with on any given day. How do

(IPL), social status by the medial prefron-

dates back some 6 million years. That is you keep up with all the complex bonds,

tal cortex (mPFC), and brokerage by

plenty of time for a gradual increase in relationships, and hierarchies between

cognitive people in your social community? Being superior temporal cortex (STC). These

fi

ndings highlight that social information

complexity, and includes the emergence, able to track the quality of your connec-

used in our everyday interactions is

in Homo, of features such as bipedalism tions to individuals within your social

encoded in brain regions known to track

and a threefold increase in brain size that group, and to subsequently track their

fl domain-general spatial navigation and

appear well adapted to more highly struc- relationships to others, re ects the topol-

psychological distance (IPL), and

tured thought, action and communication, ogies of our social networks [1].

572 Trends in Cognitive Sciences, August 2017, Vol. 21, No. 8