7. References

African Grey Parrot Personality, Food & Care – Pet Birds by Lafeber Co. Retrieved March 15, 2019 from https://lafeber.com/pet-birds/species/african-grey-parrot/

Alex, B. (2018). How Did Human Language Evolve? Scientists Still Don’t Know. Retrieved from http://blogs.discovermagazine.com/crux/2018/12/07/where-does-language-come-from/#.XMVwYegzYuU

Arthur – Alex Foundation. (2013). Retrieved from https://alexfoundation.org/arthur/

Barker, T. (2017). Zebra finch study finds mixed impact of early-life stress [Blog]. Retrieved from https://blogs.illinois.edu/view/7447/516042

Berwick, R., Okanoya, K., Beckers, G., & Bolhuis, J. (2011). Songs to syntax: the linguistics of birdsong. Trends In Cognitive Sciences, 15(3), 113-121. doi: 10.1016/j.tics.2011.01.002

Buck, R., & VanLear, C. A. (2002). Verbal and nonverbal communication: Distinguishing symbolic, spontaneous, and pseudo-spontaneous nonverbal behavior. Journal of communication, 52(3), 522-541.

Carey, B. (2007). Alex, a Parrot Who Had a Way With Words, Dies. Retrieved March 15, 2019 from https://www.nytimes.com/2007/09/10/science/10cnd-parrot.html

Chapman, M., James, V., & Barrett-Lee, L. (2012). The girl with no name. Mainstream Publishing.


Chomsky, N. (1992). On the nature, use and acquisition of language. Thirty Years of Linguistic Evolution. Studies in Honor of René Dirven on the Occasion of his Sixtieth Birthday. Philadelphia: John Benjamins, 3-29.

Darwin, C. (1871). The descent of man: And selection in relation to sex. London: J. Murray.

Erard, M. & Matacic, C. (2018). Can these birds explain how language first evolved? [Online article]. Retrieved from https://www.sciencemag.org/news/2018/08/can-these-birds-explain-how-language-first-evolved

Fromkin, V., Krashen, S., Curtiss, S., Rigler, D., & Rigler, M. (1974). The development of language in Genie: A case of language acquisition beyond the “critical period”. Brain and language, 1(1), 81-107.

Gibson, K. R., & Tallerman, M. (Eds.). (2012). Oxford Handbook of Language Evolution (p. 110). Oxford University Press.

Hakuta, K., Bialystok, E., & Wiley, E. (2003). Critical Evidence. Psychological Science, 14(1), 31-38. doi: 10.1111/1467-9280.01415

Hattenstone, S. (2013). Was Marina Chapman really brought up by monkeys? The Guardian. Retrieved April 24, 2019 from  https://www.theguardian.com/science/2013/apr/13/marina-chapman-monkeys

Hauser, M. D., Chomsky, N., and Fitch, W. T. (2002). The faculty of language: What is it, who has it, and how did it evolve? Science 298, 1569–1579.

Hedeager, U. (2003). Is language unique to the human species? Retrieved April 24, 2019 from http://www.columbia.edu/~rmk7/HC/HC_Readings/AnimalComm.pdf

Herman, L. M. (1986). Cognition and language competencies of bottlenosed dolphins. Dolphin cognition and behavior: A comparative approach, 221-252.

Holman, R. (2008). Psittacus erithacus (grey parrot). Retrieved from https://animaldiversity.org/accounts/Psittacus_erithacus/

Jablonka, E., Ginsburg, S., & Dor, D. (2012). The co-evolution of language and emotions. Philosophical Transactions of the Royal Society B: Biological Sciences, 367(1599), 2152-2159.

Kent, J. 1972. Eight months in the hospital. Paper presented at the 80th Annual Convention of the American Psychological Association, Honolulu, Hawaii, Sept. l-8.

Lamoureux, A. (2018). Why Alex The Parrot May Have Been The World’s Smartest Bird [VIDEO]. Retrieved March 15, 2019 from https://allthatsinteresting.com/alex-the-parrot-irene-pepperberg

Lehrer, J. (2008). Bird Brains: Are Parrots Smarter Than a Human Two-Year-Old?. Retrieved from https://www.scientificamerican.com/article/bird-brains-parrots-smarter/

Lyons, J. (2006). Natural language and universal grammar. Cambridge: Cambridge University Press, p.1.

Mehler, J., Christophe, A., Ramus, F., Marantz, A., Miyashita, Y., & O’Neil, W. (2000). How infants acquire language: some preliminary observations. In Image, Language, Brain: Papers from the first Mind-Brain Articulation Project symposium (pp. 51-75). MIT Press, Cambridge, MA.

Okanoya, K. (2012). Behavioural factors governing song complexity in Bengalese finches. International Journal of Comparative Psychology, 25(1).

Pepperberg, I. M. (2002). Cognitive and communicative abilities of grey parrots. Current Directions in Psychological Science, 11(3), 83-87.

Pepperberg, I. (2007). Grey parrots do not always ‘parrot’: the roles of imitation and phonological awareness in the creation of new labels from existing vocalizations. Language Sciences, 29(1), 1-13. doi: 10.1016/j.langsci.2005.12.002

Pepperberg, I. (2010). Vocal learning in Grey parrots: A brief review of perception, production, and cross-species comparisons. Brain And Language, 115(1), 81-91. doi: 10.1016/j.bandl.2009.11.002

Pepperberg, I. (2012). Evolution of communication and language: insights from parrots and songbirds. In M. Tallerman & K. Gibson, The Oxford Handbook of Language Evolution (1st ed., pp. 109-119). New York: Oxford University Press Inc.

Pepperberg, I. (2017). Athena the parrot [Image]. Retrieved from https://lafeber.com/pet-birds/wp-content/uploads/PepperbergParrot.jpg

Pepperberg, I. (2017). Inside Pepperberg’s Lab: African Grey Athena’s Antics – Pet Birds by Lafeber Co. Retrieved from https://lafeber.com/pet-birds/inside-pepperbergs-lab-african-grey-athenas-antics/

Pepperberg, I. (2019). Study shows parrots can pass classic test of intelligence. Retrieved March 15, 2019 from https://phys.org/news/2019-02-parrots-classic-intelligence.html

Radford, E. (2013). Genius African Grey Parrot Has Died [Video]. Retrieved from https://www.inquisitr.com/566539/genius-african-grey-parrot-has-died-video/

Saini, A. (2015). Language and birdsong may use the same brain structures [Online article]. Retrieved from http://www.bbc.com/earth/story/20150512-birds-hold-the-key-to-language

Savage-Rumbaugh, E. S., Rumbaugh, D. M., & Boysen, S. (1980). Do Apes Use Language? One research group considers the evidence for representational ability in apes. American Scientist, 68(1), 49-61.

Slater, P. (2012). Bird song and language. In M. Tallerman & K. Gibson, The Oxford  Handbook of Language Evolution (1st ed., pp. 96-101). New York: Oxford University Press Inc.

Smith, D. (1999). A Thinking Bird or Just Another Birdbrain?. Retrieved March 15, 2019 from https://www.nytimes.com/1999/10/09/arts/a-thinking-bird-or-just-another-birdbrain.html?showabstract=1

Stout, D., & Chaminade, T. (2012). Stone tools, language and the brain in human evolution. Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 367(1585), 75–87. doi:10.1098/rstb.2011.0099

Suzuki, T., Wheatcroft, D., & Griesser, M. (2016). Experimental evidence for compositional  syntax in bird calls. Nature Communications, 7(1). doi: 10.1038/ncomms10986

Thomas, J. (1995). Center-embedding and self-embedding in human language processing (Masters). Massachusetts Institute of Technology.

Thomas, J. G. (2014). Self-domestication and language evolution.

Thomas, J., & Kirby, S. (2018). Self domestication and the evolution of language. Biology & philosophy, 33(1-2), 9.

University of Lincoln. (2014, February 25). Reciprocity and parrots: Griffin the grey parrot appears to understand benefits of sharing, study suggests. ScienceDaily. Retrieved March 15, 2019 from www.sciencedaily.com/releases/2014/02/140225122322.htm

Vajda, E. J. (2003). Review of: An Introduction to Syntax.

Wood, S. (2005). What are formants?. Retrieved April 25, 2019 from https://person2.sol.lu.se/SidneyWood/praate/whatform.html

6. Conclusion

So in the end, do birds have language? Research has shown that there are similarities between songbirds and parrots communication and humans, but, they do not use it to the same capacity that humans do. And so, we can only conclude that while the communication systems of songbirds and parrots bear some features of language, language is still an exclusively human property. Still, there is no saying that given time, the communication systems of our feathered friends would not evolve to acquire even more features of language. As Charles Darwin writes in The Descent of Man (1871), “The sounds uttered by birds offer in several respects the nearest analogy to language.”

5. Human language

Language is one of human’s most important and unique defining characteristics, as no other creature in the world is able to use it (Hedeager, 2003). Language requires both verbal and non-verbal forms of communication in order for all parties to understand one another. Verbal communication involves forming words and putting them together to form sentences while non-verbal forms of communication include gestures, such as yawning to indicate fatigue, or pointing to bring attention to an object of interest (Buck & VanLear, 2002). The closest thing to a language would be the communication between animals as their own form of communication includes sounds or gestures which are also present in human language, such as the songs of songbirds. However, the sounds they make do not form cohesive words or sentences and hence cannot be considered language.

Although humans have language, it is not an innate ability. Animals will still behave and communicate the way others from their species do, even if they grew up in isolation. however, the same cannot be said for humans. If humans grow up in isolation, their form of communication would be similar to that of animals – gestures and noises. Since performing experiments which isolate children is unethical, there is not much research in that area. However, there have been documented cases of feral children in the past which help to shed some light on the consequences if such a thing were to happen. For instance, Marina Chapman, more widely known as “The Girl With No Name”, is someone who claimed to have grown up in the wilderness with monkeys and no human contact or communication for five years (Chapman et al., 2012). And when she was found in a Colombian jungle by hunters, she had lost her language completely (Hattenstone, 2013). Another more well-documented example would be Genie, a girl who experienced extreme social isolation and abuse from her father at a young age. According to Dr. James Kent (1972) who observed her, she appeared to have no language, making no sounds apart from whimpering and some gestures to express certain emotions. Scientists observed that she had little control over her laryngeal mechanisms and language comprehension tests also showed that she had almost no comprehension of grammatical structure (Fromkin et al., 1974). The feral children’s inability to produce language after being isolated prove that while language is something unique to humans, it is not innate.

As has been mentioned throughout this wiki chapter, language is considered by many to be a unique characteristic to humans and has the specific trait of hierarchical syntax and structure. With hierarchical syntax, the sentence “Kelly, who was out for brunch with Tim, was late to the meeting.” (Alex, 2018) tells readers that Kelly was the one who was late to the meeting, not Tim. Syntax is concerned with the way smaller words and phrases which can be organised as a unit, form sentences of varying structures (Vajda, 2003). In an article written by Alex (2018), she explains that hierarchical syntax is present when these units are organized in a hierarchical structure and embedded inside one another to form larger constituents. And it is this syntax which allows readers to correctly interpret that Kelly was the one late to the meeting, even though Tim is closer to the verb “late” in the sentence (Alex, 2018).

Alex (2018) explains one popular theory this in her article: language evolution happens in stages; the first of which is proto-language, a system of communication more complex than ape communication but lacking elements of modern language. This theory proposes that language developed as a result of evolutionary adaptation. But as for the proto-language itself and what it was like, Alex (2018) says that researchers are more split. Some argue that our ancestors sang before they spoke, while others claim that the proto-language used was dominated by pantomimed gestures – a society built on charades, which is similar to the way apes communicate today. This idea of language as an evolutionary adaptation is further explained in wiki chapter 2 and wiki chapter 15.

4. Self-domestication hypothesis

4.0 The Self-domestication of humans

Why did bird “language” (or, birdsongs) not evolve to the extent that human language (natural language) did? We may approach this question by examining the converse: Why did human language evolve to an extent unobserved in the communication system of birds? One hypothesis is the human self-domestication hypothesis. The basic idea of self-domestication is that among the driving forces of human evolution, humans selected their companions depending on prosociality. They preferred mates who were more intelligent, creative, and articulate; prosocial and cooperative behaviours were desirable in a mate. This selective pressure for more cooperation caused humans to evolve differently from other hominids, both behaviorally and cognitively. It is postulated that Self-domestication may have facilitated the emergence of complex behaviours via cultural evolution, in particular, of more complex languages in order to support more complex cultural practices (Thomas, 1994).

We may also think of self-domestication as follows: early humans adapted the environment for themselves (e.g. by making tools and erecting shelters), and subsequent generations gradually adapted to the increasingly man-made environment. Self-domestication (of humans) in this sense occurred through generations of changing and adapting to the environment without direct interference by other non-human species. As aforementioned, the selection of mates who had more prosocial behaviour was one of the driving forces of human evolution. This direction of human evolution–towards a species that possesses an increasingly complex language–potentially played a role in shaping the kind of physical environment that humans made for themselves. Therefore, it is important to consider the different factors that were at play in the self-domestication of humans, and view the process holistically.

4.1 Birds in the wild vs. Birds in captivity

Unlike humans, birds did not undergo the process of self-domestication, and this is one plausible reason bird songs did not evolve to possess all the criteria of a language. This hypothesis is supported by the observation that domesticated songbirds have songs that are more complex than their wild counterparts (Erard and Matacic, 2018; Thomas and Kirby, 2018). One example is the Bengalese finch (Lonchura striata domestica), a domesticated, possibly hybrid, descendent of the white-rumped munia (Lonchura striata). According to avicultural literature, white-rumped munias were imported into Japan in 1762 and domesticated due to their tameness. The domesticated variety of white-rumped munias were then referred to as Bengalese finches. This variety does not occur in the wild. The songs of white-rumped munias are observed to be less complex and melodious, as well as more repetitive than the songs of their domesticated descendents. There are two main reasons for the disparity in song complexity between the wild and domestic songbirds including the presence of (1) predators and (2) sympatric (i.e. closely-related or overlapping) species in the wild, including the spotted munia (Lonchura punctulata), a sympatric species of the white-rumped munia (Okanoya, 2015).

Firstly, for the white-rumped munia, singing in the wild is a dangerous activity that draws the attention of not only his potential mate, but also its predators. Consequently, the male munia bird spends less time singing as compared to his Bengalese finch counterpart. There is reduced cultural transmission in the wild munia, whereby the father spends less time teaching his song, and the son spends less time practising the inherited songs. Reduced singing time also means having less time to improvise and introduce variations to the song. Moreover, the learner’s songs are observed to have a higher fidelity to his tutor’s song. Secondly, the presence of sympatric species means that the white-rumped munias have to keep their songs simple to help distinguish their songs from the songs of other closely related bird species, such as the spotted munias. This reduces the likelihood of hybridisation and its associated disadvantages, such as lower fertility in the offspring (Okanoya, 2015; Thomas, 1994).

On the other hand, the domesticated Bengalese finch does not face the risk of being heard by predators in the safety of his enclosure, and is thus free to sing to his heart’s content. This leads to an increased role for cultural transmission of songs from father to son. With an increased singing time, the learner is able to further experiment with the tunes, improvise, and add variations to the songs. The absence of sympatric speciation means that their songs can be as colourful as they want it to be. The result is a lower fidelity of the learner’s song to his tutor’s song. Without constraints on their song systems, Bengalese finches were free to develop their songs to a higher level of complexity. This might have been one of the factors that led to the evolution of a larger brain interfacialis (one of the song control circuits) in the Bengalese finch to help it cope with the complexities of its song, which in turn further allowed for development of even more complex songs (Thomas, 1994). One Science article discusses the comparison between the songs of the two songbird species presented by ornithologist Kazuo Okanoya.

Munia song (K. Okanoya)

Bengalese finch song (K. Okanoya)

While domestication is evidenced to contribute to the evolution of language, or bird songs in this case, the lack of self-domestication in songbirds is a plausible reason that bird songs did not evolve to the extent that human language did.

4.2 Cooperation, tool-making, and human language evolution

As mentioned above, cooperation led to greater cognitive abilities in humans. Combined with extensive physical abilities, humans developed in the area of tool-making (Stout, 2012). This activity is believed to have facilitated the evolution of human language in more than one way. One instance might be the evolution of words as types of signals. For example, consider the word ‘snake’. For the early or pre-humans, the exclamation “snake!” was likely predominantly a danger signal. When humans later developed tools for hunting, the call ‘snake’ evolved to signal not only danger, but also the presence of a prey in one’s surroundings (i.e. food). Today, the modern man does not necessarily link the word ‘snake’ to a danger signal or food; we have become creative with the use of the word. For example, man conceived of Medusa with venomous snakes for hair, to represent a certain image of the Greek mythological monster.

In contrast, we can imagine that for birds, alarm calls that signal danger would not evolve to signal something else; the bird’s call for ‘snake’ will always only signal danger. One plausible explanation is that such calls do not evolve so as to retain its survival value. Therefore, we may think of bird calls as primarily for survival purposes (i.e. for preservation of both self and species), and perhaps secondarily for pleasure–a luxury not all birds can afford.

Then again, readers may ask: Do songbirds sing for their own pleasure? Perhaps they do, from time to time. For domesticated songbirds especially, it may start off with experimenting with different sounds, just because their environment allows for it at little to no cost (see section 4.1). Over time, these birds may improvise and develop their “own” songs. Seeing as how this is a self-motivated process not done out of necessity, it might suggest that some learners do find pleasure in singing, which in turn allows for the development of more elaborate songs under suitable environmental conditions. One possible test for this might be to monitor the neural activity of songbirds in the wild and in captivity. Specifically, a test could be designed to monitor and measure the dopamine signalling in white-rumped munias and Bengalese finches during their practice singing sessions. This test will possibly determine if there is a general discrepancy in the amount of dopamine signalling between the two groups. One difficulty of this study, however, is the necessary domestication of wild munias to some extent, which might interfere with the results of the study.

In short, we humans owe the evolution of our language to our greater physical and intellectual capabilities, which allowed for the development of human language to a degree not attained by birds.

4.3 Abstraction and Language evolution

Another theory regarding the more sophisticated development of human language versus bird songs discusses the link between evolutionary changes in the human brain and the emergence of abstract thought. It is proposed that the beginning of abstract thought and creative pursuits such as cave art, coincides with evolutionary changes in the human brain between 70,000 and 100,000 years ago (Saini, 2015). This could have potentially sparked the birth of the complex, sophisticated form of language we use today. Some linguists propose that similarities in speech-associated brain structures and genes in humans and birds contribute to the parallels in the evolution of human language and birdsongs. Others, including birdsong expert Johan Bolhuis, are however skeptical about this explanation of the origins of human language. In his book Aspects of the Theory of Syntax (1964), American intellectual Noam Chomsky proposes the theory of “universal grammar”, which posits the innateness of grammar to humans. The acquisition of grammar requires the capability to form abstract thoughts, such that illogical or nonsensical sentences can still be grammatically sound. Human language might be the only language that features grammar, and we owe this to our ability for abstract thinking.

Listed below are some distinguishing factors between birds and humans that may be worth consideration:

  1. Unlike (some) humans, birds probably do not try to develop an understanding of the world using a language other than their own; we may assume parallels between such an activity and the arbitrariness of human language. Just as how humans give meaning to arbitrary sounds, we may try to study and give meaning to another animal’s call, sometimes using clues from our environment (e.g. a skinny stray cat’s meow could mean hunger), other times attaching meaning to the sound possibly based on one’s whims (e.g. I think my cat misses me when he meows like this).
  2. Humans try to find meaning in words. For example, consider the word ‘snake’ which used to signal danger. Now, we may use it to describe a snaking road. Birds would never do this. (At least, they are not observed to do so). Therefore, as observed, birds likely do not have the capacity for abstraction and concepts.

4.4 Miscellaneous thoughts

  • Are abstract thoughts communicated only with words, or can they be present in other forms of animal communication such as birdsongs, gestures, sign language, etc.?
  • Do birds have abstract thought/understand concepts?
    • The understanding of concepts/abstract idea was observed in Alex, who could count. Did Alex go through a process of translation from his language to human language when he exhibited the ability to count (capacity for abstraction)? It would be interesting to study if they exhibited such behaviour in their own “language”.

3. Grey parrots and language

3.0 Who are they?

Widely regarded as one of the smartest species of birds around (Holman, 2008), grey parrots are well known for their imitation abilities, as well as their capacity for logic and certain abstract concepts.

With English as a medium and a surprising ability to answer questions, some grey parrots in particular can make it seem like they have the capacity for language.

3.1 The African Grey Parrot

Psittacus erithacus, more commonly known as the African grey parrot, is a species of the Psittacidae family that originates from the savannas, coastal mangroves, woodland and edges of forest clearings of Central and West Africa. There are two subspecies of African grey parrots, namely the Timneh African grey and the Congo African grey, of which the latter is more popular amongst pet owners (“African Grey Parrot Personality, Food & Care – Pet Birds by Lafeber Co.”, n.d.).

3.2 Vocalization and communication in the wild

In the wild, grey parrots communicate via a variety of different types of calls and vocalizations, including alarm calls, contact calls, food begging calls, and agonistic calls (Holman, 2008). They are also known to follow a daily pattern of vocalizations, where there are two main periods of vocalization in a day. The flock is generally quiet from sunset till dawn, until they vocalize at day break prior to dispersing to forage at various locations. Upon returning to the roosting site at dusk, there is another period of vocalization, and the cycle repeats the next day. The young learn these vocalizations from parents and flock mates, allowing for cultural transmission of vocalizations from generation to generation of grey parrots (Holman, 2008). Furthermore, to summarize a finding by Bottoni et al. (2003), African grey parrots are able to distinguish the similarities and differences in musical note frequencies and even master the musical code. This demonstrates their complex cognitive competence.

3.3 Vocalization and communication in human captivity

In human captivity, the physical capacities of African grey parrots ―namely speech perception and production― include being able to distinguish and reproduce most human tokens (vowels, consonants) accurately, as well as human-like formant structures (Gibson & Tallerman, 2012). Formants are concentrations of acoustic energy around a particular frequency in the speech wave, such that each different formant corresponds to a resonance in the vocal tract. These formants can be clearly observed as dark bands in wideband spectrograms, giving an estimate of vocal tract resonances in the case of voice (Wood, 2005). This thus means that grey parrots can replicate the resonances of human voice accurately. They are also able to repeat words and phrases after hearing them just once or twice. Unlike the habits of those in the wild as mentioned above, pet parrots will not learn appropriate vocalizations, but will show similar patterns and use of calls (Holman, 2008).

African grey parrots are also capable of imitation and referential communication, of which they are most widely known for imitation of human speech. This bird reaches full talking ability around a year of age, and most individuals become capable mimics much earlier (“African Grey Parrot Personality, Food & Care – Pet Birds by Lafeber Co.”, n.d.). They use reproduced English speech sounds to meaningfully interact with humans and to comment on items of interest in their lives (Gibson & Tallerman, 2012), and are able to learn novel vocalizations by isolating a sound from background noise, imitating it, categorizing the acoustic stimulus, encoding it into long term memory, and monitoring the output sound to match it with the internal template (Bottoni, et al., 2003). Grey parrots in captivity have also been observed to carry out untrained vocal practice and sound play (Pepperberg, 2010). In addition, it has been found that they learn socially, by observing moods in situations and emulating the noises used in such cases when a similar mood arises in the future.

3.4 Case study: Who was Alex?

Undoubtedly the most renowned of his kind, Alex was a grey parrot who lived from 1976 – 2007, and passed at the age of 31 years due to a deadly condition called atherosclerosis, or build-up of plaque in the arteries. For almost all his life, Alex was raised and trained by Dr. Irene Pepperberg, a comparative psychologist who had bought him at a pet store in 1977 back when she was a doctoral student in chemistry at Harvard. Dr. Pepperberg’s work with Alex began at a time when scientists had little expectation that any bird could learn to communicate with humans, and surpassing all expectations at the time made Alex a pioneer of his kind. Thereafter, the rest was history, and Alex spent the rest of his life participating in research at Brandeis University and Harvard University.

Figure 2. Irene Pepperberg with Alex the parrot

Figure 2. Irene Pepperberg with Alex the parrot (Lamoureux, 2018)

3.5 Alex’s abilities

In his lifetime, Alex achieved many milestones in Dr. Pepperberg’s lab. Some of Alex’s accomplishments and abilities included:

  • Possessing a vocabulary of up to 150 words (Lamoureux, 2018)
  • Privately vocally practising before acquiring targeted utterances (Pepperberg, 2010)
  • Actively matching memorized templates (phoneme combination, sound play) (Gibson & Tallerman, 2012)
  • Attempting to match a given word by pairing different templates of words from his memory. (Pepperberg, 2007)
  • While no direct evidence exists for birds, during a task, Alex seemingly manipulated the trainer into asking the question he seemingly desired to answer, perhaps suggesting some evidence for a theory of mind (Lehrer, 2008)
  • The ability to label 50 different objects, 7 colors, 5 shapes, and quantities up to and including six. He would combine these labels to identify, request, refuse, categorize, and quantify 100 different objects. Alex also had functional use of phases and had concepts of category, number, relative size, absence, and same versus different. (Holman, 2008; Pepperberg, 2007)
  • In the week before his death, Alex was working with Dr. Pepperberg on compound words and hard-to-pronounce words. (Carey, 2007)

Here is a video showcasing Alex in action, which abilities can you identify?

Video: Alex the parrot in action

3.6 The future: Griffin, Arthur, and Athena

Alex’s accomplishments have inspired further work with other African Grey parrots including Arthur, Griffin, and Athena. All three of them were and are respectively studied at Dr. Pepperberg’s lab at Harvard. Unfortunately, Arthur passed at the early age of 14 due to a suspected hereditary condition, which may have caused the little known avian disease Avian Bornavirus (ABV) that eventually led to his untimely death (Radford, 2013). This left Griffin to go on to become the eldest and most advanced in Pepperberg’s lab, where he can be said to be Alex’s successor.

Figure 3. Arthur (“Arthur – Alex Foundation”, 2013)

For example, Griffin can outperform children on certain cognitive tests. In one such cognitive test, Griffin was forced to gamble to test understanding of certainty versus mere possibility, and inference by exclusion. He succeeded where even human 5 year olds would fail (Pepperberg, 2019). Another cognitive test saw Griffin participating in a study into whether grey parrots understand the notion of sharing. Griffin consistently favoured the option of ‘sharing’ with two different human partners, suggesting that grey parrots can learn the benefits of reciprocity, and in turn exhibit some levels of reciprocity (University of Lincoln, 2014).

Figure 4. Griffin (University of Lincoln, 2014)

Since then, Athena has joined as the newest addition to the Pepperberg Lab. The first paper Athena contributed to was accepted for publication in 2017 (Pepperberg, 2017).

Figure 5. Athena (Pepperberg, 2017)

Figure 3. Griffin (University of Lincoln, 2014)

Figure 4. Arthur (“Arthur – Alex Foundation”, 2013)

Figure 5. Athena (Pepperberg, 2017)

3.7 Do grey parrots really have language?

Grey parrots can even outperform human children on more complex cognitive tasks and seemingly communicate with humans via natural language once trained. While this makes them appear to be capable of language to a certain extent, this is not actually the case due to three main factors.

The first is syntax, for which whatever syntax Alex had was simpler, very much unlike our complex forms of communication (Smith, 1999; Lamoureux, 2018). This alone makes it difficult to claim that Alex’s use and command of English was actually language.

The second factor can be chalked down to the needs and behaviour of the parrots in the wild as compared to in human captivity. With effective training methods under a controlled environment in captivity, Dr Pepperberg was able to push the boundaries with Alex. However, grey parrots will not naturally exhibit such abilities because these additional abilities are not necessary for survival in the wild. It should be noted that grey parrots already have their own forms of communication in the wild as mentioned earlier, such as specific periods of vocalization and various types of calls to serve their needs, making human language unnecessary for them. While it is possible to claim that Alex and Griffin demonstrated the capacity for a rudimentary form of language, it must be made clear that this was only once they were trained by humans. Without human contact, they would not have made such an evolutionary jump even if they possessed some semblance of capacity for it.

The last factor to consider is the methodology that Dr. Pepperberg used to train the grey parrots in her lab. Dr. Pepperberg attributes what she calls Alex’s ability to reason and process complex information to her training methods. These training methods  follow those of renowned behaviourist B. F. Skinner, meaning that responses may have been prompted by a very effective reward in the form of food (Smith, 1999). Although Dr. Pepperberg initially uses the particular training object itself as a reward so that the bird associates the word with the object (Smith, 1999), if the parrots were constantly prompted with enjoyable rewards, there would be no motivation or reason for the bird to think logically outside of the experiment. Without the logical thinking that comes with use of complex language, can parrots really be said to have the capacity for language? It is also possible that Pepperberg may have unconsciously given the subjects’ cues, which would have affected the accuracy and reliability of results.

Hence, with these three factors in mind, we can draw the conclusion that grey parrots do not actually have language.

2. Songbirds and language

There are over 5000 species of songbirds, all of which are of the suborder of Passeri. Their method of communication systems are songs and simple calls. They use calls for simple functions and more elaborate songs to find mates. In the first wiki chapter, the design features of Charles Hockett were introduced. In this section, we review two of them, cultural transmission and syntax, and investigate whether they are present in songbirds’ communication.

2.1 Cultural transmission

An important commonality between songbirds and humans involves the way they learn to communicate.

Firstly, they both exhibit sensitive periods in learning. While scientists do not agree on any concrete period, the general consensus is that it is during the first few years of our lives (Hakuta, Bialystok & Wiley, 2003). But for songbirds, it occurs during their first few months. During this critical period, the volume and connectivity of their brain cells responsible for song learning and production increases (Barker, 2017). If a songbird is not exposed to any birdsong during the critical period, it will still be able to sing, but only simple songs. Secondly, for their songs to develop well, they require an older bird to teach them to sing, similar to how infants require exposure to human vocalizations when they are young (Mehler et al., 2000).

Their song development occurs in two overlapping stages. The first stage, roughly 15 to 60 days after the birds hatch, involves learning songs from older “tutor” male songbirds. The second stage, occurring around 30 to 90 days after hatching, has the birds practicing, refining, and memorizing the song that they will sing for life (Barker, 2017).

Even though hatchlings learn their songs from older male songbirds, occasionally, a songbird may sing a note incorrectly. These variations from generation to generation lead to changes in their songs (Slater, 2012).

2.2 Syntax

There have been studies carried out which analyse bird songs. Berwick et al (2011) analysed the syntax in bird songs and compared them to human language. In the paper, the researchers claimed that songs had fixed sequences. The songs either contained only sporadic variation, or contained more variable sequences where a song element might be followed by several alternatives.

Figure 1. Spectrogram of a typical Zebra Finch song (Berwick et al., 2012)

Figure 1 shows that there is a clear hierarchical structure to their bird song. Their analysis showed that songs often started with introductory notes, as indicated by the ‘i’ in the figure before the actual song begins. The songs had distinct ‘notes’ which could be combined as particular sequences into syllables, syllables into ‘motifs’, and ‘motifs’ into ‘bouts’. There is a clear similarity to the hierarchical structure in the human language. In human language, we take individual phonemes (‘notes’), combine them into syllables (‘syllables’), and then into words (‘motifs’). Combining all the words together eventually forms a sentence (‘bouts’). Thus, it can be posited that bird songs consist of chains of discrete acoustic elements arranged in a particular temporal order. What this means is that they have a finite number of sounds which can be combined to form endless different meanings, a feature of human language known as productivity. Therefore, if birds have this ability it must mean they have language too.

Their capacity for productivity was demonstrated in a study by Suzuki et al. (2016) which looked to analyse the syntax of the calls of the parus minor. In one of their experiments, they played recordings of one their calls in two different orders: ABC-D (natural sequence) and D-ABC (artificially reversed sequence). The ‘D’ part of the call is used by the caller to gather the other birds to them. When the first call was played, the birds would fly close to the speaker which played the sound. On the other hand, when the artificially reversed sequence was played, the birds only responded occasionally. This experiment is evidence that birds may have a compositional syntax.

However, while the experiment was able to provide evidence for syntactic structure in parus minor bird songs, it is inaccurate to say that it is comparable to human language because they lack one fundamental aspect: semantics.

Songbirds are only able to convey limited intentions (Berwick et al., 2011). For example, if there was a predator approaching them, they would not be able to describe what the danger is, like what type of animal it is or how many there were. They would only be able to convey notions of flying or danger.

Thus, Berwick et al (2011) concluded that they do not have grammatical syntax but only phonological syntax. This means that there are only a certain set of units that can be arranged in particular ways, and these arrangements may not necessarily create new meanings.

Another reason bird communication cannot be considered language is that their system is not unbounded in length and structure.

In human language, sentences can be embedded within other sentences and recombined endlessly to form longer and longer sentences. Take for example the sentence “the hunch that the serial killer who the waitress had trusted might hide the body frightened the FBI agent into action” (Thomas, 1995), there are three clauses: “who the waitress had trusted” which is embedded in the clause “that the serial killer might hide the body” which is then embedded in the main clause “the hunch frightened the FBI agent into action”. This exhibits the open-ended novelty that Wilhelm von Humboldt famously called the “infinite use of finite means”(Chomsky, 1992), and a cornerstone in what human languages were.

Birds on the other hand have a limited ability to construct phrases. They are mostly limited to an AnBn phrase structure (Hauser et al., 2002). Thus, although songbird songs share some similarities with human language, they are not advanced enough to be considered language as they also lack other key design features of human language.

Chapter 21 – Debate between Biological and Cultural Adaptation

2019: Ang Ying Xuan, Valerie Tiong Hui Ling, Wan Muhammad Ariff

1. Introduction and Aims of Discussion

1.1 What is Universal Grammar?

    1.2 The Origin of Universal Grammar

        1.2.1 Adaptationist

   The Adaptationist Problem

        1.2.2 Non-Adaptationist

   The Non-Adaptationist Problem

        1.2.3 How About Minimalism?

2. Cultural Transmission

    2.1 What is Cultural Transmission?

    2.2 Effects on Language

3. The Neural and Cognitive Basis of Language

    3.1 What Helps Shape Our Language

        3.1.1 Constraints from Thought

        3.1.2 Pragmatic Constraints

        3.1.3 Cognitive Constraints

        3.1.4 Biological Constraints

   Vocal Apparatus


    3.2 Universal Human Constraints

4. Problems of Gene-Language Co-evolution

    4.1 What is Gene-Language Co-evolution?

    4.2 Plausibility of the existence of Gene-Language Co-evolution

        4.2.1 Reasons for its improbability

        4.2.2 Reasons for its probability

5. Conclusion


1. Introduction and Aims of Discussion

Universal grammar (UG) is one major theory which has garnered much attention in contributing to possible explanations for the origins of our language acquisition ability. It has been and continues to be widely discussed, and many have tried to establish that if it does exist, from where does UG originate. However, as with any discussion, problems with these proposed theories are present too, ultimately leading us to discuss the question of whether the evolution of UG took place, and if not, then what other possibilities exist on the evolution of language, from a biological standpoint.

Hence, we begin by establishing the logical problem of language evolution that stems from the most commonly discussed perspective on UG. Next, we explore other explanations that might provide insight into the evolution of language, such as the cultural transmission of language and the neural and cognitive basis of language. Following this will be a discussion on problems from a biological standpoint of language evolution, before we finally conclude our findings.

Before we can begin to understand the core of the debate, we must first understand some of the discussions about what UG is, and where it might have come from.

1.1 What is universal grammar?

Universal grammar is a theory which proposes humans have inborn facilities relating to language acquisition (Barsky, 2016), composing of a set of subconscious rules which enable us to determine a correct sentence formation. It is based on the idea that specific features of syntactic structure are universal, and indeed, it has been proven that there are 5000 to 6000 languages, in spite of their vastly different grammars, which possess a common set of syntactic rules and principles (Dubuc, n.d.).

As such, it is important to understand that UG encodes universal, though arbitrary to communication, principles of language structure.

1.2 The Origins of Universal Grammar

There exist multiple theories as to how UG might have come about, some discussing it as either having evolved from something, others as an appearance by chance. The particularly major few we will discuss below are the adaptationist and non-adaptationist approaches to evolution of UG in the brain.

1.2.1 Adaptationist

Adaptation is about the natural selection of preferred genes which are the determiners of biological constructions that enhance fitness, with regards to predetermined numbers of possible offspring. A biological structure would be most able to contribute to fitness by fulfilling a function. For instance, the heart is thought to pump blood, the legs to enable movement from one place to another, and UG, to support language acquisition. The better the structures are able to fulfill their function, the more contributive they would be and hence naturally be selected. The adaptationist hence proposes that UG arose from specific brain processes particularly relating to the acquisition of language (Christiansen & Charter, 2008). These processes have evolved overtime, undergoing many cycles of natural selection, through selecting particular random genetic transformations over long periods of time, providing specific humans with a clear advantage in adaptability. However, it remains unconfirmed what the advantage which language provided was, whether in ability for better coordination of hunting parties, danger warnings, or communication between sexual mates (Dubuc, n.d.). The Adaptationist Problem

The problem starts where according to the adaptationist view, as an adaptation to the linguistic environment, universal language properties would eventually become genetically encoded. As such, it is the aspects which are most likely to lead to improved communication which would be positively selected. In other words, the functional aspects of language. For example the compositional character which language posses is a functional aspect, as the ability to express in an infinite number of messages using a finite number of lexical items (Christiansen & Charter, 2008) serves great communicative function.

However, UG, according to Chomsky, is made of linguistic rules which seem largely conceptual and arbitrary, lacking any functional implication. This arbitrariness suggests that however the arbitrary principles are combined, they still remain similarly adjusting to our usage, provided we communicate with similar arbitrary principles in mind.

Hence, there are three main issues with this idea, regarding the dispersion of human populations, language change, and genetic encoding (Chater & Christiansen, 2012). Firstly, there exist many different environmental conditions and scenarios regarding language evolution and the migration of humans, through which diverse language groups would have emerged. These different groups would have adapted accordingly to suit the conditions of their linguistic environment, instead of forming a universal language faculty, and hence they would not adopt the same arbitrary principles across the groups. Secondly, even if we are to consider just a single population, the rate of change of linguistic practices would still be higher than the rate of genetic change, thus natural selection would not be able to catch up, this will be further elaborated on later in section 4.2.1. Thirdly, it is strange that UG would have encoded the arbitrary and abstract aspects of human languages, when natural selection brings about adaptations made to suit the existing environment, and these would be the ability to grasp and internalise the precise features of the early language-like communicative methods created by ancient hominins, not the supposed ability to acquire any of the vast possibilities of languages which no one had ever come across before (Christiansen & Chater, 2008).

1.2.2 Non-Adaptationist

The non-adaptationist’s view is that UG did not come about due to adaptation to an environment, but instead appeared by some variation in chance. For example, as a side-effect of an increase in brain size or still undiscovered physical or biological evolutionary constraints, as hinted at by Chomsky. Non-adaptationists usually view UG to be both extremely elaborate and profoundly distinct from other biological structures. They argue that UG seems to be unlike anything seen before in its attributes and composition, that there is a very low chance of it being a result of natural selection amidst unpredictable mutations. The Non-Adaptationist Problem

The likelihood of accidentally forming a completely operating, and entirely new, biological feature by chance is exceedingly small. Even though tiny genetic modifications result in alterations of extant sophisticated systems, and these alterations can be fairly extensive, the production of new developments is not a possible result, as a gene alone is not able to form a completely new function, from the ground up. The arguments for UG is that UG is both extremely coordinated and complicated, and entirely different from generic cognitive rules. Hence the appearance of a supposed UG requires the creation of a novel, complicated structure and what we have discussed is that the probability of even limited new intricacy appearing by chance is exceedingly low (Christiansen & Charter, 2008).

1.2.3 How About Minimalism?

Unlike previous arguments about the evolution of UG, minimalism views UG from a different perspective of what it might actually consist of and hence inviting new possibilities and insights into the different perspectives regarding language and its evolution. Minimalism views the language faculty as a ‘minute organism’, with limited and basic features (Boeckx, 2006). It depicts the brain’s language ability originating from a multitude of plastic cerebral circuits making up the brain, and it is this plasticity which allows for an innumerable amount of concepts. The brain then continues to correlate sounds and concepts, and the properties of grammar that we abide by would exist as the outcome, or by-products, of how language functions. One of these concepts of minimalism, is recursivity, which is the ability for one clause to be embedded inside another (Dubuc, n.d.). It was thought to have originally developed to help us solve problems such as with numerical computation or social relationships. By linking recursivity with the other motor and perceptual skills required for this utilisation, humans became competent in complex language because of recursivity. And so the evolutionary biologist, Hauser, suggested that the content of UG may be highly limited, comprising solely of recursivity.

However, if UG consisted only of recursion, UG would not sufficiently explain how the acquisition of language is possible, considering that language input we receive at a young age is random fluctuating in accuracy and is imperfect, and the consistencies of natural language are both extremely complicated and arbitrary (Chater & Christiansen, 2012).

Hence, after considering all these theories, it is evident that there is a need to conduct further research into other areas that might provide other possible explanations.

2. Language as shaped by Cultural Transmission

Chater and Christiansen offer Cultural Transmission as an alternative to explaining the link between UG and language evolution. Cultural Transmission is the process of learning new information through socialization and engagement with those around you. In linguistics, it is the process whereby a language is passed on from one generation to the next in a community. While language could have emerged from genetically-specified UG, it is cultural transmission that catalyzes language evolution. Essentially, it is believed that language, while being formed by cultural transmission, is needed for transmission of other cultural information.

There have also been other studies conducted and articles written that further supports this idea.

Daniel L. Everett studied the language and culture of an indigenous Amazonian tribe in Brazil, the Piraha. He viewed language as a “solution to the communication problem” which aligned with the view above and covered how language and culture were of influence to each other. Everett sees language as “a kind of cognitive enhancing tool but one that is learned and not innate”. This suggested that language was chiseled and sharpened like a tool by cultural transmission.

Recent works by Kenny Smith suggests that linguistic structure develops through cultural evolution, as a result of repetitive cycles of learning and persistent language uses. Smith agrees that “human language allows the open-ended transmission of information”, similar to Chater and Christiansen. Smith believes that social learning is essential, where we use the language of our linguistic community and acquire language through immersion in the rich linguistic environment of the community. This is in line with the definition of cultural transmission.

K Smith from University of Edinburgh states that “Language is a culturally transmitted system – children learn the language of their speech community on the basis of the linguistic behavior of that community.”. Smith further suggests that it is such cultural transmission that results in the possibility of cultural evolution of the linguistic system, which essentially translates to language change over a period of time as a consequence.

With that in mind, it is likely that cultural transmission does shape language. Nevertheless, it is good to note that there is the plausibility that cultural transmission and language are co-dependent on each other and requires the need to look at language evolution with the ‘nature’ with ‘nurture’ point of view. See 3. Cultural Evolution for more information regarding this co-dependency.

2.1 Effects of Cultural Transmission

Language is generally acquired through cultural transmission. Human offsprings naturally pick up languages that they hear most during the critical period of language acquisition. Nonetheless, even in cultural transmission, there have been evidences that suggest that genes also play a role. Studies have shown that the geographical distribution of the variant forms of the two genes active during brain development, ASPM and microcephalin, correlates with the distribution of tonal languages. For example, in places where the ancestral form of the genes is most common, such as in Southeast Asia and sub-Saharan Africa, the languages, such as Chinese and Yoruba, tend to be tonal. Where the derived form predominates, such as in Europe, West Asia, and North Africa, the languages, such as Spanish and German, are non-tonal. It was suggested that different forms of gene direct the cultural evolution of language over multiple generations by causing differences in the brain structures that affect how people hear or speak a language. This meant that cultural transmission of language could shape it in terms of functionality like usage, convenience of communications, with the background help of selective genes. However, further evolution of language is limited by the biological and cognitive constraints of humans.

3. The Neural and Cognitive Basis of Language

Chater and Christiansen (2012) proposes that languages are probabilistic tendencies which are shaped by universal human constraints.


Blue Box – All Language possibilities

Orange Arrows – Universal Constraints that limit the Language possibilities

Green Circles – Different languages of the world

3.1 What Helps Shape Our Language

These universal human constraints, which are cognitive and biological in nature, limits the possibilities of linguistic structures that could be learned, processed and transmitted from person to person or generation to generation. Some of these constraints includes; the constraints involving the nature of Thought, constraints from the communicative function of language and constraints from our cognitive mechanism, among a number of other human constraints.

3.1.1 Constraints from Thought

Language allows us to communicate our thoughts. Hence, the nature of thought would surely strongly influence the structure of language. One property of Thought is that Thought is not constrained by a finite inventory of ‘messages’; it consists of a compositional structure in which a limited set of perceptual inputs can create an unlimited set of possible developments. Hence, in order to communicate Thought, language would be shaped in the essence of Thought in having a compositional structure, with a finite set of lexical and grammatical resources to encode an unlimited set of possible messages.

3.1.2 Pragmatic Constraints

The purpose of communication is to convey as much information as efficiently as possible. This influences the development of all languages in trying to create a system that is able to convey as much information as possible with the least effort. Hence, we find universal trends in languages such as the grammaticalization of certain concepts such as ‘aspect’ or ‘tense’ and the occurrences of nominals in most language systems.

3.1.3 Cognitive Constraints

Languages must correspond to human’s sequential learning ability. From early child language acquisition studies such as the Wug Test (Berko, 1958) and familiarization preference procedures (Marcus, Vijayan, Bandi Rao & Vishton, 1999), children have been found to be both rule-learners and statistical learners. The process in which humans learn, process and memorize hence ensure that languages has to be logical and structured such that it can be decoded when transmitted from one person to another. See 4.1: Child Language Acquisition for an in-depth analysis.

3.1.4 Biological Constraints Vocal Apparatus

A human is able to produce sounds between 85 Hz and 155 Hz. This also means that voiced human languages must fall between these frequencies. This constraint was the reason used to differentiate why apes such as Washoe were unable to produce human speech (Harley, 2009) although this particular biological constraint on apes was debunked by Tecumseh Fitch as he proved that monkey’s vocal tracts are human speech-ready (Fitch, de Boer, Mathur & Ghazanfar, 2016). Memory

The limitations to memory too can affect how human language develops. Humans do not have a powerful memory, hence the language we produce would tend to be local rather than long-distance.

3.2 Universal Human Constraints

The greater the number and complexity of constraints that we can identify, the harder it is to unpick them although paradoxically, the greater the number of constraints that we can identify, the simpler it is to understand the universal process of language acquisition. This is because the more constraints there are that are universally shared by all humans, the smaller the number of available options for ‘language’ that a speaker can have.

For studies and real examples of Cultural Adaptation in Language Evolution, see Chapter 3: Language as a Cultural Adaptation

4. Problems of Gene-Language Co-evolution

4.1 What is Gene-Language Co-evolution?

Gene-Language Co-evolution is the idea that biological and language evolution follow the same trajectory, whereby language is a heritable, innate trait like genes. This means that both language and genes are subjected to processes of natural selection. In biology, natural selection is “the process whereby organisms better adapted to their environment tend to survive and have more offspring”. It is regarded as the main process that causes evolution. With that in mind, in the linguistic environment, natural selection would result in adaptations to local environments, resulting in different biological characteristics among different populations of language users.

4.2 Plausibility of the existence of Gene-Language Co-evolution

4.2.1 Reasons for its improbability

As previously mentioned in 4.1, this phenomenon is only possible if language is able to undergo natural selection like genes. Chater and Christiansen suggests that UG could not have co-evolved with natural language itself as they felt that such an occurrence was implausible, evolutionarily speaking. The reasonings are as follows.

Linguistic change is much faster than genetic change. This is due to the ever-changing linguistic environment which causes the supposed “linguistic genes” to be unable to adapt. As such, these supposed genes would have a difficult time undergoing natural selection. Besides, the diffusion of the human population leads to a wide diversity of languages. With gene-language co-evolution only capable of adapting to current linguistic environment, it will not sustain since modern human populations do not seem selectively adapted to learning their own language. This is shown by fact that babies are able to pick up any language as long as they are exposed to it. As such, gene-language co-evolution fails to exist.

4.2.2 Reasons for its probability

Before going into the reasonings, there is the need to define the conditions for natural selection in language. In biology, natural selection occurs when the 4 conditions are present – hereditary, reproduction, variation in fitness or organisms and variation in individual characters. For language, Chater and Christiansen believes that it takes place when the arbitrary and functional aspects of the linguistic environment are present. The arbitrary aspects refer to the absence of any natural or necessary connection between meaning and its sound and form while the functional aspects refer to things like vocabulary size, emphasis on local linguistic processes and so on. Since both aspects are present in the linguistic environment, natural selection could occur and this means that gene-language co-evolution is plausible in this context.

Many studies have been done in favour of this belief that gene and language co-evolves. In one such case, an evolutionary theorist at Harvard University, Erez Lieberman, discovered that English verbs are regularized at a rate inversely proportional to their frequency. This discovery is backed up by evolutionary biologist, Mark Pagel, who deems that this frequency proves that rates of lexical replacement are comparable to the evolutionary rates of genes. This serves as proof of the possibility of language undergoing natural selection like genes and hence, poses the plausibility of gene-language co-evolution.

5. Conclusion

In conclusion, it can be seen that many studies have been conducted in this area, however more studies from cross disciplines may help in establishing a clearer understanding  of language and the brain, hence more studies can be done in across these multiple disciplines to better garner a stance regarding our topic.


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Chapter 16 – Co-Evolution Of Language And The Human Brain

2019: Vivien Lee Hwee Sze, Roshni Jaya Sankaran, Yeo Pei Yun

2017: Rumaizah Binte Abdul Raof, Noor Ikhmah Binte Roslie, Alvina Chan, Kajol Nar Singh

1. Introduction

The existence of language presupposes a brain that allows it (Schoenemann, 2009). How our brain became adapted to language has long been debated. According to researchers, there was a co-evolution of both brain and language to allow one to adapt to the other (Deacon, 1997). But how did this happen?

We shall attempt to explore the answers to this question  through this chapter – how different parts of the hominid brain evolved to provide the basic capacities for language, the factors that facilitated hominid brain growth, and how language eventually emerged amongst Homo sapiens and why. We shall also delve into the Mirror System Hypothesis, a highly contested and prominent theory,  in our attempt to track the genesis of the human language.

2. How The Brain Evolved For Language

Both the brain and language share a complex and interdependent relationship. Our capacity to use language depends on the existing abilities of our brain, and similarly, our need to communicate with one another likely brought about changes in the brain to allow for the emergence of language (Schoenemann, 2009).

Different parts of our brain have changed or evolved over the course of human evolution to possibly contribute to our ability to use language, but the most notable change is the brain’s significant increase in size.

2.1 Increase in Brain Size

The human brain is said to have increased steadily in size from about 2 million to 300,000 years ago. It is about 5 times bigger than expected when compared with an average mammal of our body size, and it is also about three times bigger than that of the average primate of our body size (Schoenemann, 2009). These significant increases in brain size should have been functional adaptations, or they would have been selected against, as it is metabolically expensive to maintain large brains. One unit of brain tissue is said to require 22 times the amount of metabolic energy that is needed for the same unit of muscle tissue (Aiello, 1997). Larger brains are also linked with longer maturation periods in primates, which leads to fewer offspring per unit time (Schoenemann, 2009). The fact that the brain continued to increase in size despite these evolutionary costs suggests that the benefits of having a larger brain outweigh the cons.

Fig. 16.1 A visual representation of the growth of the hominid brain. 

One other benefit of a larger brain is how it possibly led to a greater number of distinct cortical areas in the brain (Kaas, 2013). As a result, specific areas of the neocortex, which is a brain structure involved in higher cognitive functions such as language, became less connected to one another, which allowed those areas to carry out tasks independently of one another. This brought about functional localization, which might have contributed to the development of language areas in humans (Schoenemann, 2009).

2.2 Neocortical Evolution Of The Human Brain

The neocortex makes up the largest part of the cerebral cortex, which is the outer layer of the cerebrum. It consists of grey matter. It is considered the ‘center of extraordinary human cognitive abilities’ (Rakic, 2009) because it is responsible for a variety of higher-order brain functions such as sensory perception, cognition, generation of motor commands, spatial reasoning, and language.

Most language evolution theories have focused on the concept of neocortical evolution following the groundbreaking findings of Broca and Wernicke that demonstrated how neocortical damage led to a loss of language ability. The evolution of the neocortex in mammals is deemed fundamental in the development of higher cognitive functions of the brain.

The first step in the evolution of the human cerebral cortex was its enlargement, which occurred mainly by expansion of the surface area without a comparable increase in thickness (Rakic, 2009). This increase in neocortex size was likely influenced by increased pressures for cooperation and competition in early hominids (Sternberg & Kaufman, 2013)

2.2.1 Broca’s and Wernicke’s Areas

Broca’s area is located in the posterior-inferior frontal convexity of the neocortex, whereas Wernicke’s area is localized to the general area where parietal, occipital, and temporal lobes meet (Schoenemann, 2009). Both Broca’s and Wernicke’s areas are typically found in the left cerebral hemisphere of the brain. Damage to either of them results in either Broca’s aphasia, sometimes referred to as ‘non-fluent aphasia’, or Wernicke’s aphasia, which is a kind of ‘fluent aphasia’.

Fig.16.2 The arcuate fasciculus links the Broca’s and Wernicke’s areas directly to each other.

A tract of nerve fibers known as the arcuate fasciculus directly connects both Broca’s and Wernicke’s areas to each other, thus allowing the two areas to interact and mediate complementary aspects of language processing (Schoenemann, 2009). The arcuate fasciculus is believed to have been modified during the course of human evolution, and these modifications could have played a role in the evolution of language (Aboitiz & Garcia, 1997; Rilling et al., 2008). A comparison with the homologues of Broca’s and Wernicke’s areas in macaque monkeys’ brains led to the finding that the direct connection that links Broca’s and Wernicke’s area to each other was missing (Aboitiz & Garcia, 1997). The homologue of Wernicke’s area in macaque monkeys was found to project to prefrontal regions that are close to their homologue of Broca’s area, but not directly to it (Aboitiz & Garcia, 1997). Therefore, the arcuate fasciculus must have undergone some kind of change during human evolution to enable a more direct connection between the Broca’s and Wernicke’s areas.

Additionally, it was found that the human arcuate fasciculus projects to the temporal lobe of the brain, but this projection was much smaller or absent in nonhuman primates (Rilling et al., 2007). This suggests that new connections between the temporal lobe and Broca’s area were likely to have been established after the divergence of the human and chimpanzee lineages, and these connections subsequently linked regions that are involved in lexical-semantic and syntactic processing in the modern humans (Rilling et al., 2007).

Both Broca’s and Wernicke’s areas have also been found to be significantly larger in absolute and relative size when compared to the brains of macaque monkeys (Petrides & Pandya, 2002) though it is still not clear if the increase in size has any correlation to the evolution of language.

2.3 Non-Neocortical Evolution Of The Brain

The role of non-neocortical structures in the evolution of speech has received significantly lesser attention over the years. However, non-neocortical structures such as the cerebellum and basal ganglia have also been linked with language and speech functions, for example in reading and language processing tasks (Booth, Wood, Lu, Houk & Bitan, 2007). In addition, lesions to the basal ganglia and cerebellum are known to be able to disrupt speech (Gibson, 2011).

The emergence of such studies has called for greater emphasis on the anatomy of the whole brain and its connectivity, so as to better understand the neural origins of language. The sections below describes two key non-neocortical structures of the brain, namely the cerebellum and the basal ganglia, and how they might have adapted for language.

Fig.16.3 Locations of the basal ganglia and cerebellum in the human brain.

2.3.1 Cerebellum

The cerebellum is involved in the modulation of a variety of linguistic functions such as verbal fluency, word retrieval, syntax, reading, writing (Murdoch, 2010), as well as speech perception, speech production, and semantic and grammatical processing (Ackermann, Mathiak & Riecker, 2007; De Smet, Baillieux, De Deyn, Marien & Paquier, 2007).

A recent study suggests that the cerebellum’s involvement in sensory-motor skills, imitation and production of complex action sequences may have contributed to the evolution of humans’ advanced technological capacities, such as tool using and making, which in turn may have been a preadaptation for language (Barton & Venditti, 2014).

2.3.2 Basal Ganglia

The basal ganglia is made up of a group of subcortical nuclei mainly accountable for executive functions and behaviours, emotions and motor learning (Lanciego, Luquin & Obeso, 2012). It participates in a vital circuit loop that functions in the selection and voluntary execution of movements (Bear, Connors & Paradiso., 2007). These circuits connecting the cortex and the basal ganglia have been found to aid in both language production and comprehension, since it has been found that afflicted basal ganglia results in motor problems, issues with the comprehension of syntax and the processing of semantic information.

The basal ganglia have been found to be twice as large in absolute size as predicted based on body size. This suggests that this increase in absolute size could be attributed to aiding in higher cognitive functions, such as language (Schoenemann, 2009), as one would expect it to scale closely with overall body size if it was only involved in motor functions. Additionally, biological adaptations of the basal ganglia following the advent of bipedalism could also have formed the key adaptations needed for language (Lieberman, 2003).

3. Gestures and Language

Research has found that the left hemisphere is crucial in producing both vocal and sign language as the same region and similar neural structures were activated when patients either spoke or signed (Pollick & Waal, 2007). This relation between gestures and speech are further depicted in primates where it is shown that gestures are an integral part of their communication.

Gestures can vary according to the different species of primates. For example, while a gorilla may beat its chest to show aggression, chimpanzees will organize coordinated assaults to express the same emotion. This exemplifies how gestures might lay a concrete foundation for the evolution of language.

It has been suggested how the combination of gestures with vocalizations could have created intentional vocal communication as an appendage through the process of ontogenetic ritualization. Thereafter, the brain developed to accommodate the need to produce and articulate certain phonemes. Critics of this gestural theory have pointed out that it is difficult to pinpoint the reasons as to why primates would choose to adopt this less effective mode of communication. However, since primates are shown to only have control over hand movements, it can be deduced that gestures could have very possibly acted as a precursor to the evolution of the human language.

These observations greatly support the gestural theory being the genesis of the human language, which is further supported by the distinctive enlargement of the brain and vocal apparatus. Furthermore, the presence of gestural communication in human infants prior to the development of speech, as well as  the right-hand bias of both ape and human gestures (Pollick & Waal, 2007) provides support for the concurrent development of the brain structures, improved gestural communication and subsequently language capabilities.

3.1 Mirror System Hypothesis

The mirror system hypothesis is a theory which posits that language sprouted from proto-sign instead of the continuous development of vocalizations. This theory relies heavily on the concept of praxis, which is defined as the process by which a theory is enacted or realized. This hypothesis shows how praxic hand movements could have evolved into the gestures used for communication by apes, which was then passed down to and spread along the hominid line. This also implies that the mechanisms that support language in the human brain evolved from a basic mechanism that was not originally linked to communication. This indicates that the mirror system for grasping had the ability to produce and pick up on a set of actions provides the evolutionary basis for language parity. It is important to note that the mirror system hypothesis does not indicate that this is all it takes to support the evolution of language. However, it does argue for a key role in the evolution of the mechanisms that support extensions of mirror systems for both praxis and then for communication.

3.1.1 Apes and Gestures

Apes in general have a limited range of gestures that vary from each phylogeny of the species. Any new gestures that emerge are then postulated to have been created and learned. Tomasello and Call (1997) posited a process of ontogenetic ritualisation. They suggest that a dyad may acquire a new gesture. Additionally, they also offer the concept of human supported ritualisation to explain why captive apes may learn to point, even though this behaviour is not seen in the wild (Arbib, 2017).

In the case of apes, an integral aspect of the life of chimpanzees, for example, includes using a distinct type of arm raise with the intention to indicate that they are about to commence play (Goodall, 1986). Through this, we can see how an action that originally encoded other purposes, has now evolved to become a communicative signal. In some other species like orangutans, the infants suck on the mother’s lips as she is consuming food to obtain the morsels of food from her (Bard, 1990). At around 2.5 years old, they begin enacting gestures that include going towards the mother’s face to get food instead of physically touching her lips (Liebal et al., 2006).

Though ontogenetic ritualization may be the main mechanism involved in establishing a standardized signal between a pair of individuals, other mechanisms may be needed if gestures are supposed to be spread to the whole community. Some gestures are also found to be confined to a specific group of chimpanzees and are not observable in another group. This thereby rejects the theory that ontogenetic ritualization is the only procedure by which any type of gesture is acquired (Goodall, 1986). This is evident through how two orangutan communities in two different zoos have been observed to offer their arm along with morsels of food. Meanwhile, only a single group of gorillas were seen to enact gestures that included the shaking of the arms and another gesture known as the chuck up (Liebal et al., 2006). In addition to this, some other gestures such as the chimpanzees’ hand clasp  is indicative of grooming. These gestures solidify the theory that social learning does play a key role in how gestures are acquired by apes (Nishida, 1980; Pika, Liebal, Call et al., 2005; Whiten et al., 2001).

Arbib (2012) postulates that in the case where a gesture could quite possibly be formed through the process of ontogenetic ritualization, each member of the group will have the ability to acquire it independently within a dyad. The moment this gesture is concretized however, it has the possibility of being spread to the rest of the group via social learning. Additionally, it can be rediscovered by dyads who then begin to enact them on their own accord through their own interactions (Arbib, 2012).

3.1.2 Broca’s Area and Mirror Neurons

According to Arbib (2017), the “F5 in the premotor cortex of the macaque that contains mirror neurons for grasping is homologous to (is the evolutionary cousin of) Broca’s area of the human brain, an area implicated in the production of signed languages as well as speech”. The F5 area of the premotor cortex controls praxic movements that occur during grasping and between the hand and mouth. This area in a monkey brain controls the hand-related motor neurons in which have an interesting characteristic that involves them being fired or triggered when  the monkey not only carried out an action itself but also fired when the monkey observed a human or other monkeys carrying out a similar action. This ties in together with the hypothesis that neurons could possibly learn ‘to associate related patterns of sensory data rather than being committed to learn specifically pigeonholed categories’ (Arbib,2012).

Arbib (2012) suggests that the ‘language-ready brain’ belonging to the first homo sapiens did in fact support protosign and protospeech. He proposes two possibilities as to how this may have occurred. The first possibility is that languages could have evolved directly as speech (MacNeilage, 1998), and the second possibility  is that it stemmed from sign language (Stokoe, 2001).

His approach suggests that from Homo Habilis onwards, they possessed a protolanguage that has its roots in manual gestures. This provided the structural foundation for a protolanguage that was based off vocal gestures. However, both the development of the protosign and protolanguage should be viewed as something that occurred concurrently alongside each other.

Arbib (2012) argues that once protosign had stabilised, conventionalized gestures could displace other pantomimes in terms of possessing a highly flexible semantic structure. This could allow protospeech to continuously develop, as some vocalizations began to be conventionalized as well. ‘The demands of an increasingly spoken protovocabulary might have provided the evolutionary pressure that yielded a vocal apparatus and corresponding neural control. This supported the human ability for rapid production and co-articulation of phonemes  that underpins speech as we know it today. Data on hand-voice correlations in both monkey and human are adduced in support of this view’ (Arbib, 2012).

The darwinian view suggests that phonology ranked first in the skill to produce songs without any type of meaning. However, according to Jespersen (1921), various songs became connected with various social contexts and this allowed for the transformation from holophrasis to small phrases  in a manner similar to biological evolution charted by the mirror system hypothesis to the cultural evolution. There were numerous mechanisms that evolved in order to be able to support protosign and had to extend collaterals with the purpose of gaining control over the vocal system. This vocal system supported an increasingly  accurate control of vocalization needed to support speech. However, this proved to be solely adaptive and it could have only occurred when protosign developed over the scaffolding that pantomime provided in order to supply open-ended semantics.

3.2 Counter-Evidence To The MSH

Conversely, there has been existing literature studies arguing against Arbib’s (2012) mirror system hypothesis. Two puzzling aspects of the hypothesis were pointed out.

3.2.1 Argument 1: The mirror system is not essential for either the signed or spoken language processing.

Arbib (2012, p. 174) postulates that “the mechanisms that gets us to the role of Broca’s area in language depend in a crucial way on the mechanisms established to support a mirror system for grasping.” He argues that mirror neurons exist and they encode articulatory form of signs and words. These neurons fire whenever a sign is articulated or seen, or when a word is spoken or heard. He also asserts that mirror neurons mediates understanding as they function as a part of the neural circuitry (Arbib 2012, p. 139).

However, studies have shown that the Broca’s area does not demonstrate properties related to a mirror system for either sign or speech. Evidences suggest that the mirror system does not play a significant role in language processing for both visual-manual and auditory-vocal languages.

For speech, research studies carried out by Hickok et al. (2011) provide evidence that the Broca’s area is not critical for speech perception. For instance, patients with lesions to the fronto-parietal human mirror system (i.e. Broca’s area) performed at ceiling level during syllable discrimination and word comprehension tests. This indicates that damage in Broca’s area does not necessarily cause deficits in speech perception or comprehension. Furthermore, the degree of speech fluency does not correlate with word comprehension or syllable discrimination ability (Hickok, 2010). It was discovered that intact and precise speech perception abilities are found for 1) babies who are unable to fully control their speech articulators, 2) individuals going through the Wada test which inhibits their ability to produce speech (Kaufman & Milstein, 2013), and 3) individuals with developmental anarthria, a neurological disorder that prohibits speech production. Ergo, findings suggest that if mirror neurons for speech are present, they are insignificant for speech perception.

For sign, it is uncertain if sign-related mirror neuron populations exist. Even so, there is little evidence that they are essential in the comprehension and perception of sign language. According to Hickok at al. (1996), deaf patients who suffer injury to their Broca’s area have unimpaired sign comprehension and perception, even though they exhibit deficits in sign articulation. In a study done by Corina and Knapp (2008), it was suggested that the inferior parietal cortex, namely the supramarginal gyrus, was involved in sign comprehension and production. However, conjunction analysis conducted by the same researchers revealed overlapping activation in the superior parietal lobule instead of the inferior parietal cortex (Knapp and Corina, 2010). When the supramarginal gyrus was damaged by electrical stimulation, it was found that the ability to imitate signs remains unaffected while the ability to produce sign became disrupted (Corina et al., 1999). Therefore, findings conclude that if sign-related mirror neurons exists, they hold little significance in sign perception.

Emmorey et al. (2010) conducted an experiment on deaf signers and hearing individuals who have no knowledge of sign language. They were tasked to passively view video clips of ASL verbs (e.g. to-dance) and pantomimes (e.g. peeling an imaginary banana) while activities in their neural system were being examined. Results showed that for deaf signers, the Broca’s area were engaged during the perception of ASL verbs but not during the perception of pantomimes. Conversely for the hearing non-signers, both ASL verbs and pantomimes strongly activated the fronto-parietal cortex even though both were meaningless to them. Due to the lack of engagement with the mirror system for the deaf subjects, it was alluded that human communication does not require automatic sensorimotor resonance between action and perception.

All in all, impairments to the Broca’s region or to premotor regions does not cause deficits in comprehension and perception of signed and spoken language. A mirror neuron system does not seem to underlie language perceptions for signers and speakers.

3.2.2 Argument 2: The mirror system hypothesis is not consistent with the properties of co-sign or co-speech gesture.

Arbib (2012) argues that the “pervasiveness of co-speech gesture in modern human language users supports his hypothesis as the multimodality of modern language could be the evolutionary result of multimodal protolanguages”. The issue with that assertion is that the modern equivalent of protosigns, namely conventionalised gestures that are specific to individual cultures and more arbitrary in form such as the horns gesture or the ‘ok’ gesture, are not produced concurrently with speech (McNeill, 1992). Additionally, pantomimes do not occur simultaneously with speech, but rather, as a “component” gesture or a type of demonstration produced distinctly from speech. In a way, both modern protosigns and pantomimes repel speech in regards to both expressivity and timing.

Gesticulation plays an important role as they take place simultaneously when an individual is speaking (McNeill and Duncan, 2000). They are not the same as conventional gestures or pantomimes. It was suggested that co-speech gestures combines multiple thought elements concurrently whereas sign and speech convey thought elements individually by segmenting them into phrases, words, or morphemes. Likewise, he posits that for sign and speech meaning is categorized and combined into hierarchical structures, whereas gestures express meaning globally. For instance, the hand location, movement, or shape acquire meaning only as parts of a whole. Both speech and gestures are intertwined (Mayberry and Jaques, 2000).

However, it was unclear how or why this highly synergistic relationship between speech and gesture emerged from the expanding spiral between protospeech and protosign. It is also unclear how protolanguage (a combination of protospeech and protosign) evolved into the integrated semiotic system of gesture and speech detected in modern humans.

According to Sandler (2009), signers produce co-sign gestures with their mouth. For instance, when manually signing ‘bowling-ball’, puffed cheeks indicating the roundness is produced concurrently. Thus, presenting evidence that mouth gestures are non-combinatorics, idiosyncratic, synthetic, and global. It was concluded that “speakers gesture with their hands, signers gesture with their mouths (2009 p. 241).”

A question arises, what is the rationale for co-sign gestures during signing? A possible conclusion is that users of language convey thoughts using a system that includes synthetic, global, imagistic schemas (conveyed in gesticulations with the body, face, or hands), as well as combinatorial, codified meaning structures (demonstrated with signed or spoken language). It remains perplexing as to why modern signers produce gesticulations and signs in the same modality and how protosign evolved into gesticulation.

4. References

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Bear, M. F., Connors, B. W., & Paradiso, M. A. (2007). Neuroscience: Exploring the brain (3rd ed.). Philadelphia: Lippincott Williams & Wilkins.

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Emmorey, K., J. Xu, P. Gannon, S. Goldin-Meadow & A. Braun. (2010). CNS activation and regional connectivity during pantomime observation: No engagement of the mirror neuron system for deaf signers. NeuroImage 49. 994–1005.

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Hickok, G., M. Costanzo, R. Capasso & G. Miceli. (2011). The role of Broca’s area in speech perception: Evidence from aphasia revisited. Brain & Language 119. 214–220.

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Chapter 13 – Manual Gesture: A Window to Language Evolution

Co-Authors: Dana Yeo, Yebin, Tze Kiat


Hi there, welcome to our Wikiblog!!! 🙂

In this wiki chapter, we hope to provide insightful content on how the study of manual gestures is related to language evolution. We will be referencing most of our information from “The Oxford Handbook of Language Evolution” edited by Tallerman and Gibson. Simply by exploring sign languages, there are many discoveries that can be found to help linguists piece the puzzle of the evolution of language. We will first start the content with gestures in primate communication and then slowly unveiling to gestures that people use in current times.

Here are our aims for this WikiChapter:

  1. Investigating gestures of primates in view of how it can related to the language evolution in human.
  2. Explaining about the origins of language in manual gestures.
  3. Exploring gestures in current times to find out more about evolution.

Continue reading to find out more!!!

2. Gesture as modality of primate communication

2.1 Why do we look at gestures in primates?

We can look to extant non-human primate communicate to help shape the discussion of gestures as a window to language evolution. As evolutionary linguistics focuses on biological adaptation for language, studying primates that share a common ancestor with humans might give us some understanding on how our language might have evolved. A gesture that occurs in these primates as well as humans has a high possibility that it is also present in our last common ancestor.

Homonin Lucy

Though vocal modality seemed to be an innate complex communication for humans, studies have argued that hominin ancestors used manual gesture in a linguistic capacity prior to speech (Arbib, Liebal, & Pika, 2008). Hominins are a group consisting of modern humans, extinct members of humans’ lineage, and all our immediate ancestors. Thus, looking into manual gestures can be useful for the discussion of language evolution.

2.2 Manual Gestures in primates: Examples






Primates regularly use manual gestures, facial expressions and body posture for communication. For instance, chimpanzees and bonobos wave at each other, shake their wrists when impatient, beg for food with open hands held out, flex their fingers towards themselves when inviting contact, move an arm over a subordinate in a gesture of dominance (Pollick, Jeneson, & de Waal, 2008). We can all agree that humans ourselves use these actions to interact with one another too. However, as compared to their gestures, the sign language that humans use is much more complex as we are able to convey a lot more intricate messages through it.

2.3 Manual Gestures in primates: Lack of Variety

The simple manual gestures that primates use, lack the variety that is as wide as what our sign language systems have. For primates, a manual gesture can be used in different situations but carries entirely different meanings in each context. An example, a bonobo stretching out an open hand towards a third party during a fight signals a need for support, whereas the same gesture towards another bonobo with food signals a desire for a share (Pika, Liebal, Call & Tomasello, 2005). However, there is hardly such a case for sign languages. It is unlikely that they have actions that can be used in a particular context while at the same time conveying an entirely different meaning when the exact same actions is used in another context.

2.4 Manual Gestures in primates: Population-specific


Chimpanzees have population-specific communicative behaviours which is comparable to the cultural variations of gestures in humans. Some of the behaviours can only be found in specific areas. The chart above shows examples of population-specific communicative behaviours (Boesch, 1996).


Present in only Tai and Mahale, “Hand-clasp”: Two chimpanzees clasp hands overhead, grooming each other with the other hand.





Absent in only Bossou,”Play-start”: When initiating social play, one of the youngsters will break off a leafy twig or pick up some other objects, with this in mouth or hand he approaches his chosen playmate.



Similarly to humans, there are cultural variations of gestures. and gestures can mean very different things in different cultures. For instance,


This sign can mean “okay” in the Singapore and United States while in Greece, Spain or Brazil, it means you are calling someone an a**hole.


2.5 Manual Gestures in primates: Multimodal Signalling
Facial expressions






Multimodal signalling is a combination of communicative signals such as vocalization, gestures and facial expression. This can be found in both humans and primates. Studies have shown that chimpanzees seem to combine gestures with vocalizations more often than gestures with facial signals, while bonobos exhibits no bias toward either a facial expression or a vocalization when combining their gestures.

For human, due to our anatomical changes, we use a lot more vocalisation now. Complex vocalisation is the main mode for communication while gestures and facial expressions are complements. Something that our closest relative, chimpanzees and bonobos are unable to develop.

From here, we can see how language have evolved along with our anatomical changes and how it has given us the ability to use all sorts of multimodal signals to express ourselves and even developing language systems like sign language which stems from manual gestures and the spoken language.

2.6 CONCLUSION: Linking back to Language Evolution…

By looking at all these similarities humans have with primates, this opens up to language evolutionary possibilities as to how manual gestures could have evolved into spoken languages and then to sign languages.

The Early Hominins could have started communication by using a language structure that was similar to manual gestures and as Hominins started to evolve biologically, so did the language systems.

3. The origins of language in manual gestures

3.1 Development

How did language evolve? As distinct systems of communication, there are two effective modes of language that are available to us, these being verbal language and manual gestures. Nowadays, humans habitually use the former to express their intentions, with the latter being a kind of supplement to get the message across. However, it seems likely that this was not always the case. Instead, manual gestures once held priority, with vocal elements only gradually coming to take centre stage later on in the evolution of humanity.

(cf. Corballis 2002; Armstrong and Wilcox2007; Rizzolatti and Sinigaglia 2008)

3.2 Intentionality

Intentionality is a philosophical concept and is defined by the Stanford Encyclopedia of Philosophy as “the power of minds to be about, to represent, or to stand for, things, properties and states of affairs”. Basically, just by virtue of focusing and directing your mind towards something, you have a directed intentionality towards it. With regard to language evolution, systems of language, whether verbal or gestural, are all intentional systems in themselves. As it is the mind from which the ability to communicate originates, it is by observing what living beings are prone to do in their natural environments which better enables us to grasp their innate capacity for language. For instance, attempts to teach great apes anything resembling human speech have failed (Hayes 1952), but reasonable success has been achieved in teaching them forms of visible language (Savage-Rumbaugh et al. 1998). This suggests that early hominins were much more predisposed to and thus more likely to have possessed an intentional system of communication that was based primarily on manual gestures and not vocal calls.

3.3 The power of time

Eventually, evolution came. Our brain sizes began to increase dramatically. Somewhere along the line, verbal language started to appear. We became able to share complex intentionalities and build complex systems. For verbal intentional systems, eyesight is no longer a limiting factor as is the case with manual gestures. Past limitations regarding communication that would correspondingly have vanished include the inability to communicate at night due to the darkness and over longer distances, where the other party is not within one’s view. With spoken words becoming the new priority, our ancestors would have been able to go from just miming to a more complex and useful intentional system. We became able to make tools and share thoughts on the past and future rather than just the present. This culminated in the fruits of our progress that we see today, even as our languages are constantly conventionalised or ‘updated’ over time, due to globalisation, necessity and the like. While such a process is much more apparent in radical, sweeping changes to language systems, subtle new phrases always still pop up.

4. Gesture as good venue for innovation

If the children are given instruction in how to solve the problems, they are more likely to profit from the instruction than children who were told now to gesture. Gesturing thus brings out implicit ideas, which in turn, can lead to learning. (Broaders et al, 2007)

We can even introduce new ideas into children’s cognitive repertories by telling them how to move their hands. For example, if we make children sweep their left hand under the left side of mathematical equation  3+6+4=__+4 and their right hand under the right side of the equation during instruction, they learn how to solve problems of this type. Moreover they are more likely to succeed on problems than children told to say ‘The way to solve the problem is to make one side of the problem equal to other side” (Cook et al, 2007).

Besides,  according to Goldin-Meadow et al(2009), gesturing promotes new ideas.  The children may be extracting meaning from the hand movements they are told to produce. If so, they are sensitive to the specific movements they produce and learn accordingly. Alternatively, all that matter is that the children are moving their hands. If so, they should learn regardless of which movements they produce. In fact, children who were told to produce movements instantiating a correct rendition of grouping strategy during instruction solved more problems correctly after instruction that children told to produce movements instantiating a partially correct strategy, and the latter group solved more problems correctly than children told not to gesture at all.

Therefore, manual modality is a good venue for innovation because ideas expressed in this modality may be less likely to be challenged than ideas expressed in more explicit and recognised oral modality. Because gesture is less monitored than speech, so may be more welcoming of fresh ideas than speech.

5. Gestures to Sign Language

5.1 From gestures to co-speech

The origin of human language has always been a debated topic. One hypothesis is that spoken language originally derived from gestures (Kendon, 2016; Armstorng, Stokoe & Wilcox, 1995 & Corballis, 2002). Gestures, a universal feature of human communication, functions as a visual language when verbal expression is temporally disrupted. It is often used for dyadic interactions. In fact, language areas in the brain, such as Broca’s area, are particularly active when observing gestural communication (Paulesu, Frith, & Frackowiak, 1993 & Zatorre et al., 1992). Thus, this is in line with Condillac’s (1746) suggestion that spoken language developed from gestures to speech.

However, it is worthy to note that spoken language does not evolve immediately from gestures. Rather, co-speech gestures (where speech is more vocalizations rather than actual speech here) sets in before spoken language. This was evident in early language acquisition in children where word comprehension and production occur after nine months of age whereas intentional control of the hands and babbling occur before eight months of age (Rochat, 1989; Iverson & Thelen, 1999 & Vauclair, 2004).  Bernardis and Gentilucci (2006) also highlighted that sound production was incorporated into the gestural communicative system of male adults when interacting with objects or when meaning of abstract gestures were required. Sounds can provide more salience to the gestures when communicating information to other interlocutors. Thus, the use of gestures with sound confers an advantage in the creation of a richer vocabulary.

Furthermore, speech and gestures share common neural substrates. Not only was there a tendency to produce gestures at the same time as the spoken word, information conveyed verbally was also reduced as gestures supplement it, and vice-versa. As such, it is evident that vocalizing words and displaying symbolic gestures with the same meaning are controlled by a single communication system.

5.2 From co-speech gestures to spoken language

While it may seem that co-speech gestures provided a more enhanced communication system, co-speech gestures have limitations. Steklis and Harnad (1976) mentioned them as follows:

  • Gestures are of no use in the dark, or across partitions
  • Inability to refer to the absence of the referent or past / future
  • Eyes and hands are occupied
  • Slow and inefficient when
    > Several people are communicating
    >Crucial information is immediately required

These limitations could have led to increasing reliance on spoken language. Furthermore, it was emphasized that gestures were already somewhat arbitrary by this time. Thus, spoken language became the obvious solution to the above mentioned limitations.

Spoken language evolution is also closely linked to biological evolution. Fitch (2000) highlighted that control over vocalization was largely due to the modification of the vocal tract in two positions. A slow descent of the larynx to the adult position was seen from babies of three months of age is said to have an impact on vocalization (Sasaki et al., 1977). It allowed more room for the human tongue to move vertically and horizontally within the vocal tract (Lieberman et al., 1969). On the other hand, the importance of tongue and lips in constricting the airways also played a role in vocalization (Boe et al., 2017). Furthermore, increased brain complexity allowed creation of more complex meanings through combinations of sounds (Jackendoff, 2006). This developed into more complex linguistic elements such as lexicons and sentences.

5.3 Sign Language

Spoken language is natural and ubiquitous. But, how about people who are unable to communicate verbally or have hearing impairments? Some create their own language: a sign language.

According to StartASL.com (2017), Aristotle was the first to have a claim recorded about the deaf. He theorised that people can only learn through hearing spoken language. Deaf people were therefore disadvantaged and were unable to learn or be educated. This led to the first documentation of sign language in 15th century AD which was said to be French Sign Language (FSL). Then, different sign languages such as American Sign Language (ASL) began to emerge based on FSL because of the necessity for the language to communicate and educate deaf people. However, some sign languages emerged organically without being modeled on earlier sign languages such as Nicaraguan Sign Language (NSL).

Manual modality conveys information imagistically, and this information has an important role to play in both communication and thinking. It changes its form and itself becomes segmented and combinatorial. We see this phenomenon in conventional sign languages passed down from one generation to the next, but it is also found, and is particularly striking, in emerging sign languages.

Conventional sign languages are autonomous languages, independent of the spoken languages of hearing culture for deaf. Sign languages are combined to create larger whole sentences, and these signs are themselves composed of meaningful componenets (morphemes). Many signs and grammatical devices do not have an iconic relation to the meanings they represent. It was evident in a study conducted by Klima and Bellugi(1979), that the sign for ‘slow’ in American Sign Language(ASL) is made by moving one hand across the back of the other hand. When the sign is modified to be ‘very slow’, it is made more rapidly since this is the particular modification of movement associated with an intensificataion meaning in ASL.

6. What sign languages tell us about language evolution

Here are some insights on language evolution that can be gleaned from studying sign language, especially emerging sign languages.

6.1 Sign Language in general

Studying the fingerspelling development of deaf children can potentially explain how Hockett’s ‘duality of patterning’ feature arose. Duality of patterning is the ability to create meaningful units (utterances) from non-meaningful units (phones or individual sounds like /p/ in ‘pat’). Research shows that deaf children initially treat finger-spelt words as lexical items rather than a series of letters representing English orthography. They begin to link handshapes to English graphemes only at around age 3 (Humphries & MacDougall, 2000). However, this link is not based on phonological understanding of the alphabetical system. Rather, they view it as visual representations of a concept. This will be illustrated further using a fingerspelling experiment done with deaf children. In an experiment by Akamatsu (1985), some children produced correct handshapes (shape of the fingerspelled alphabet) but wrong spellings while others had correct spellings but wrong handshapes. In the former, the order of spelling is not important to them as long as all or most of the elements in a word are present (refer to Fig. 1 and 2). In the latter, the deaf children blend together letters from the manual alphabet instead of spelling them individually thus affecting the shape of the fingerspelled alphabet. Thus, he proposed that the children were analyzing fingerspelling as a complex sign rather than a combinations of letters. Only at about 6 years of age, when they started going to school, were they able to understand the rule that governs spelling. From this, we draw that humans do not naturally produce these alphabets or phones as a precursor to language use. In fact, it is the converse; we develop language first before realising that it could be broken down into smaller units. This could also hold true for language evolution. Long vocalisations could have come first.  Then people realised that they could be broken up and recombined to form other meanings.

Fig.1: Fingerspelling of the word ‘Ice’

Fig.2: Wrong order of fingerspelling for the word ‘Ice’

6.2 Emerging Sign Languages

Research into emerging sign languages may give us a glimpse of how early human language could have evolved as we can closely observe the inception and development of a new language. It tells us why and how language could have evolved, given a fully developed human brain and physiology.

With this is mind, what then does emerging sign languages tell us about language evolution? First, there must be a community of people who communicate in that language. This community must consist of more than just a few people. A family unit is thus insufficient. Home signs can develop in a family of at least one deaf signer and other hearing members. But it will not evolve into a language. A larger group of users is needed for language to evolve. One reason for this is the need for at least two generations of signers for a rudimentary sign system to evolve into a language (Senghas, Senghas & Pyers, 2005). The first generation provides a shared symbolic environment, or vocabulary. The second generation then uses the signs created by the first generation in a more systematic manner and develop a grammatical system. Hence, we can postulate that a proto-language needed to have been used by a community of people for it to eventually develop into a full-blown language such as English. However, there is no known fixed number of speakers that ensures these rudimentary systems eventually evolve into  languages.

Second, a shared vocabulary develops first before grammar. This is seen when observing first generation users of emerging sign languages. They have a strong tendency to use only one nominal in each sentence. For example, to convey ‘A girl feeds a woman’, first generation signers would instead sign ‘WOMAN SIT’, ‘GIRL FEED’. This can be attributed to the lack of grammar to differentiate between Subject (‘A girl’) and Object (‘a woman’) in the first generation (Meir, Sandler, Padden & Aronoff, 2010). Thus, language could be said to have developed word first and grammar develops slowly afterwards.

Third, words could have started as iconic and gradually become more arbitrary. This is seen in emerging sign languages. Younger signers (2nd generation onwards) simplify signs created by the first generation (Erard, 2005). For example, as shown in Fig 3., the sign ‘MAN’ among older Al-Sayyid Bedouin Sign Language (ABSL) signers is the gesture of a mustache twirl, presumably because men have mustaches. But for younger signers, it is merely twisting the index finger at the upper lip. Thus, signs that were initially iconic gestures start to lose certain characteristics that represent the physical objects they embody and become more arbitrary due to minimization of movement. This could also have happened to spoken languages where words may originally have been more onomatopoetic but were simplified by later generations until they bear little or no resemblance to the actual referents.

Fig. 3: Simplification of the sign for ‘MAN’ in ABSL

Moreover, the way and rate at which a language evolves may be influenced by the community. For example, NSL and ABSL are emerging sign languages. Yet, both have markedly different grammars. NSL, similar to more developed sign languages, has a rich inflection system which reduces its reliance on a strict word order (Erard, 2005). An example of inflections in NSL is how signing two actions slightly to the side instead of forward indicates that the same person is doing both actions (Senghas, Senghas & Pyers, 2005). Conversely, ABSL does not have rich inflections and instead relies on strict word order to avoid ambiguity (Fox, 2007). Some attribute this to the nature of the two communities. NSL is considered to be a deaf community sign language whereas ABSL is a village sign language. This means that ABSL developed among people of the same village. Whereas NSL developed among a group of people who lived in different areas but were brought together for some reason, usually for education. Thus, NSL has a bigger, more diverse community than ABSL and also has more members joining the community each year. This may be the cause of NSL’s more accelerated grammatical development. Interestingly, while all emerging sign languages are developing syntax, there is no single path to its development. ABSL relies heavily on word order while Israeli Sign Language (ISL) is developing verb agreement and relies less on word order. Despite being emerging sign languages, both are not developing the same areas of syntax or grammar. Conversely, they are going in totally opposite directions with regards to word order and morphology. This could imply that different languages evolved differently from the very start.

7. Conclusion

Up till today, the debate over the origins of human language is still highly contentious. The theory that we were exploring in this WikiChapter is one that hypothesised that language evolved from gestures. As humans evolve, spoken language was created and replaced gestures slowly. Languages in current times are far more efficient as compared to the early days. By investigating the manual gestures that primates used, the origins of language in manual gesture, to finally how sign languages are developed and made so much more complex in modern days, we managed to unveil how gestures can be a window to language evolution. 

With that, we hope that our wikichapter has helped you to understand language evolution better! 🙂


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