From Hand to Mouth: The Happenstance of Human Language Origins

Reference & EducationCollege & University

  • Author Robert Depaolo
  • Published October 12, 2023
  • Word count 2,883


This article discusses the origin of human language in terms of the happenstance mechanisms of natural selection - not as a capacity that evolved "in order to" enhance human communication and/or aid in survival but as a trait that (as grammatically and semantically precise as it now seems) arose virtually accidentally from a juxtaposition of neural systems in the human brain: specifically, the relationship of the human hand to the human mouth in evolutionary/neurological ontogeny.

It seems discussions of natural selection often inadvertently veer in the direction of purposefulness, even though Darwin's underlying premise was that traits and skills arise from random mutations - fitness and usage only coming later The divergence into purpose is understandable. When one looks at the behaviors, traits and skills of humans in particular, it is difficult to imagine that luck of the draw led to the works of Shakespeare, the discoveries of Einstein and the mathematical elegance of Maxwell's equations.

While advocates of natural selection believe traits and skills occur through a random (planless) process they often lapse into phrases such as..."The behavior of the leopard in hoisting prey up to tree branches evolved to enable it to eat without competition."

That lapse certainly comes into play when it comes to the origins and evolution of human language. In a sense the existence of communication among any organism (and most have some degree of it) seems too functional to have developed in random fashion. For example, what randomly evolved anatomical features disposed creatures to recognize, distinguish between and send messages to one another? Certainly an alignment of the vocal apparatus would allow for elaborate sound making but why the purposeful nature of that sound making - particularly in creatures that have only bare bones neural circuitry like ants and bees who communicate prolifically ?

When it comes to humans the task of attributing language acquisition to natural selection becomes even more difficult, but not impossible. Several theories of human language origin have addressed the issue. Indeed, there are so many theories that the process of determining which is most valid seems as complicated as language itself.

One theory (often referred to as 'continuity theory') has human language not so much evolving as emerging abruptly and in essentially final form resulting from an abrupt genetic shift in the human brain. (Watermill, Chomsky et al. (2014). Other theories (under the rubric of 'discontinuity') presume human language evolved more in accord with the gradual pace of evolution with foundational components that were contributed by earlier hominid and primate species: a version supported by the fact that primates had long ago established hand to mouth neurological connections through their eating habits.

There are specific accounts of how human language emerged. Pika & Mitani (2006) and Schippers, Roebuck et, al. (2010) believe the prototype for human language began with gestural communication while Rappaport (1999) and Knight (1998) suggested human language has its roots in the codification of social and religious rituals.

Darwin felt human language eventually served the purpose of discerning between valid communication (truth) and deception among group members giving language a crucial probative role in winnowing out liars and preserving survival enhancing group solidarity. Once again. however, the central question is not what ultimate purpose language served but how such a complex capacity could have emerged in the accidental fashion implied by natural selection.

In order to address this question a critical component of language must be discussed - neurology. At the risk of diverting from the main topic it seems appropriate to first refer to the second signal system theory of language offered by Ivan Pavlov. He suggested human language is essentially a reflexive response to action serving to encode, memorize and guide behavior as a way to solidify learning. His idea was that language began as an obligatory accompaniment of experience, which naturally coincided with his classical conditioning model of behavior. For years the validity of this theory was debated in scientific circles and in a sense the debate has not been completely resolved. However fairly recent studies offer insight into its validity.

It is well-established that pathways in the parietal and frontal cerebral cortex governing movements of the hand, fingers and mouth are adjacent to each other. That alone increases the potential for "spillover" - as seen in everyday experience when people automatically gesture while speaking to create emphasis and increase the clarity of expression. Anatomically that would make it highly probable that there would be a verbal concomitant of manual behavior. Whether it was ingrained enough to be considered reflexive (vs. a happenstance ocasional neuro-behavioral spillover) was yet to be determined even though it seems clear that in child development there is a correlation between hand and mouth movements and dependency of one on the other in establishing speech capacities. (The toddler first explores manually; touching holding, putting objects in his mouth, then, later on demonstrating his curiosity by constantly asking "why").ventually, research on the topic of hand-to-mouth neural interactions provided closure.

Sergey Stravinsky, working at the Department of Neurosurgery at the Stanford Neuroscience Institute found that neurons on the motor cortex previously thought to control hand and arm movements were activated during speech in a way that mimicked the neural activity seen in language expressive neural circuits. In other words, this study seemed to suggest that hand movement and language activation were isomorphic and in a broad neurological context functionally the same. Another study by Desmurget et al. (2014) confirmed this finding.

From this one could infer that the moment fine motor skills, especially tool making, began to play a prominent role in human (and hominid) activity some type of vocal accompaniment would have tended to occur alongside manual activity. That could in part answer the question of how human language could have originated in a way compatible with natural selection. Still, that does not answer the question of how human language became so complex.

Once again there are theories. One (which this writer believes is valid) alluded to a manual/vocal origin of human language (erns and Teva, 2016). They suggested tool making entailed a grammatical version of movement that would have driven human language toward a formal language structure. Just how could this play out? Some possibilities come to mind.

To explain how, one merely has to develop a correlation (or perhaps more accurately a "mirror effect") regarding what happens during tool making and the nature of human speech. A possible scenario might be as follows.

Nuts, Bolts and Words

Language - any language, regardless of how formal, must include parts of speech. Specifically nouns, verbs, descriptive words and the outcomes of actions - i.e. some sort of punctuation of an experience or activity.

In beginning the task of tool making - using flint tools as an example, selection of a good rock often would have come first. That involves scanning and selecting. It is an action and perception-based version of a noun but also of an adjective. Not only is a specific rock picked out as a single entity (not a person or place but definitely a "thing") but the selection is also based on its quality....The hominid might think to himself: "It is flatter than others in the pile and easier to chip."

Beyond that is the actor himself. Having selected a particular piece of flint he must engage - but ever so subtlety. Too much force and the stone will break up. Too little and, and he won't make the edge sharp enough to cut meat. Therefore, the motor act involves a perception of the actor - thus the implicate use of the pronoun..."me." In other words, he must be aware of his own efficacy throughout the task via a self-monitoring capacity. Finally, as the flint tool is perfected there must be a capacity to acknowledge that the task has been successfully completed. That comprises the punctuation, and in effect, the period at the end of the action/sentence.

The interesting aspect of this scenario is that while it paints a picture of a primitive human at work it actually shows that the flexibility of human language with its capacity for inversions, redundancy and metaphor might have pre-human (hominid) ancient origins.

For example, the act of tool making can be expressed in a variety of sequences. The tool maker might have selected a perfect stone earlier, stopped to eat then returned to the task; in which case he might begin with the verb or action phase. In that case the "action sentence" might contain only a verbal - no adjective or noun is needed. Then again, having honed his craft through practice he might not need to process his own responses and can take "me" for granted. In that case no pronoun is needed.

Thus, depending on when and how the task begins the action/sentence structure can vary. Just as the stone carver can enact his motor behavior in that way so can a modern human omit parts of speech in communicating to others. The latter might say: "Gotta pick me out a nice stone, make sure I concentrate and do it right"....or perhaps..." Time to do the cutting"...or perhaps..." I was tired last time, have to get my act together or the stone won't turn out right....and finally..." Great! now that's a good cut - mission accomplished!"

In other words. The inversion capacity and general flexibility built into human language would have been possible at the very outset of human language evolution once vocalizing was paired up (quite neuro-naturally) with manual activities such as tool making - and not to leave out females various weaving and meal preparation activities (assuming those were some of their roles).

Still there are other factors to consider. Theories regarding rituals. gestures and other preliminary aspects of human language seem valid. We do use language in those ways and probably did during its inception. In addition, the continuity theory regarding sound making mimicry seems valid. For example, all the great apes have imitative behavioral tendencies. That is perhaps why humans find it so amusing when a comedian does impressions. On some, possibly atavistic level the act of imitation seems appealing to us, possibly because it is so natural and neuro-behaviorally friendly.

So, what is the bottom-line solution to the question of origins? It might be found in Darwin's idea of a conversion, which refers to a skill evolving that can be utilized in many different ways. The fact that the human brain is so large and interconnected would have virtually mandated multiple uses of language.

On the other hand, it also makes sense to think in terms of an evolutionary skills hierarchy when it comes to language. Rituals would no doubt prompt the use of language in capturing and embellishing religious and social experiences. However, that would not necessarily lead to a language structure and without language rules it would be difficult for tribe members to communicate clearly with one another. The basic tenet of information theory speaks to that. Also, while gestures could prompt vocal correlates, they would not necessarily entail a grammatical structure. Certainly it would be possible to use gestures as stimulus cues- for example regarding the arrival of predators or the threat of thunder. However, any sort of communication approximating human language would be lacking. The same could be said about the honesty/deception model. While it is important to discern truth from lies within a group, to do that requires a formal language structure - if for no other reason than to cut through the deception.

Even if one resorts to Darwin's notion of sexual selection (whereby females select mating partners based on their language prowess) an absence of rule-based expression would be prohibitive. For that reason, it seems the manual/motor hypothesis might have been the original template for human language structure. In a quintessentially bio-natural context that makes sense because it might provide an answer to how human cognition led to language grammar.

Still in chicken-egg fashion one could ask - before vocal accompaniment first occurred during manual tasks, how the human brain knew how to structure the tool making sequence? In other words, how did pre-humans learn the action grammar? One possible answer might be that human perception must align with the essence of the natural world. i.e be designed to process events as they occur according to physical laws that govern motion and time. All animals have this capacity. The lioness knows she must first stalk, hide and remain downwind to avoid being detected by the gazelle. Only after attending to those tactics will she strike. The leaf cutter ant knows something about the plants it harvests, pertaining to availability, seasonal trends and so on. It understands "when and where" The sperm whale knows the sequence of its breathing rhythm well enough to time its dive and come up for air before drowning. Finally, the female squirrel realizes preparing a nest must occur after coitus.

The natural world operates according to before-after sequences, typologies and categories, species and individual characteristics, beginnings and endpoints. Nature has a grammar. Ends cannot come before beginnings and things all have unique characteristics, life spans and descriptive components. All species living in the natural world would have to have some sort of synchrony with the world in which they live in order to survive and in that context a sense of action order would have to some naturally to them. Regardless of brain volume, level of cognitive ability or learning capacity. It is not a question of evolution but one of obligatory juxtaposition. The organism is a function of physical laws therefore must adhere to those laws and interact with nature in terms of those laws. That process benefited the first human toolmaker/speaker.

Finally, in addressing the question of language origins one must consider two components of language that exist only in human language - the language of mathematics and figures of speech: for example, simile, metaphor onomatopoeia etc. Origin through onomatopoeia is easy to explain. Indeed, some theorists believe human language expression began with sound making that imitated animals and natural acoustical phenomena, for example (Ladja 2011). With regard to metaphor and simile resolution becomes more difficult. However, such capacities might be (and likely are) attributable to two phenomena. First the language and fine motor cortical areas are housed in a cortical site generally referred to as the associative cortex. Because of the inter connectivity within this site and its innervation into many other brain sites it makes sense that sensory impressions can be gathered to create associations beyond the concrete.

A second explanation pertains to the brain's architecture which is arranged similar to the branches of a tree. Given such an arrangement one might expect branches closest to one another to mingle in association and expression so that, for example the pairing "She is as pretty as a flower" (simile) or... "She is a flower" (metaphor) would be more likely paired than "She is as pretty as a Volkswagen" or....'"She is a pineapple." "She" and "flower" can be closely connected to the branch "attractiveness" which facilitates the comparison, whereas one must traverse many more branches on the cognitive tree to come up with comparisons between a woman and a tropical fruit. In a sense, if one requires a term to consolidate this concept - it might be referred to as the law of associative proximity.

When it comes to the language of mathematics origins might have come a bit easier. Math is simply a symbolic/linguistic expression of spatial relations. Bigger, smaller, deeper, shallower, farther, nearer, more or less forceful.... those are all concepts a tool making migratory hominid would have needed and used to survive.

As to the question of which hominid was the first to use language. One suspects all toolmakers had some semblance of language. Perhaps even chimps using makeshift straw-tools to extract termites from tree trunks ostensibly have an impulse to open their mouth and move their lips or tongue. As tool making became more sequentially precise so did the language grammar. of hominids and humans. In line 'associative proximity' as the human brain expanded its networks language associations and elaborations became increasingly more elegant.


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Rappaport, R. (1999) Ritual and Religion in the Making of Humanity. Cambridge, UK Cambridge University Press

Schippers, M. Roebuck, A. Renken, R. Nanette, G. Keugers, C. (2010) Mapping the Information Flow from One Brain to Another During Gestural Communication Proceedings of the National Academy of Sciences in the USA 107 (20) 9388 - 9393

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Robert DePaolo Retired Practitioner in the fields of clinical, educational and neuropsychology. former professor of psychology in NH University System, auth or of eight books and many articles on science. education. religion and psychology

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