Chapter 15 – Evolution of Nonverbal Communication in Hominids

> Chapter 15 - Evolution of Nonverbal Communication in Hominids

1. Introduction

The human race was challenged but flourished over centuries on Earth. Be it environmental, social, economical and psychological obstacles,  our ancestors cemented themselves as advanced creatures – existing through survival of the fittest; cultural establishment, industrial revolution and globalization of today. These accomplishments are not merely due to our intelligence or adaptivity but also our inherent skill for effective interpersonal and social communication. However, back 2 million years ago,, our species as many other creatures now do, interacted primarily through bodily expressions. Our ancestors developed, adopted and utilized non-verbal communication as their “shared” language system for the very need of survival and socialization before the maturity of their complex vocal apparatus. This is exactly why this paper is on the nonverbal domain – its roots run deeper beyond spoken and written language. The social and emotional reciprocation via nonverbal communication (which is what AIs cannot imitate and explicit speech and words are limited to) is what establishes us as a superior race on Earth, therefore it is significant to understand the evolution of this pioneering system in support of our future as better communicators.

2. Biological Evolution

Biological evolution refers to anatomical and physical changes to the body that give rise to various cognitive functions. First of all, we will be sharing with you these changes as Homo Habilis gradually evolve to Sapiens. Then, in the later part of the WikiChapter, we will be addressing how these biological aspects contribute to non-verbal communications displayed in the hominids.

2.1 Brain Size

When biological evolution is involved, the most prominent change would be the brain size. Within the Hominids family, gradual increase in brain size had been observed since the days of Great Apes to that of Homo Genus. This change had been an ongoing and consistent process in through the stages of the Homo series, particularly from Homo Habilis to Erectus to Sapiens. Three factors have been found to be correlated with the increase in brain size, so read on and find out more!

Brain Lobes


Expansion of brain lobes and change in brain organization are evident with the emergence of Homo habilis, including modest expansion of the frontal and parietal lobes along the stages of the Homo Genus evolution. The frontal lobe is the part of the brain that manages important cognitive skills in humans such as emotional expression, problem solving, memory, language, judgment, and sexual behavior. It is often referred to as the ‘control panel’ of humans’ personality and our ability to communicate. As the homos progressively possess a larger frontal lobe, executive human functions get increasingly prominent; emergence of speech production and ideologies to solve problems such as creating hunting tools are examples of how the homos are potentially becoming more human-like. On the other hand, the parietal lobe is vital for sensory perception and integration, primarily with the visual system. With an increasing parietal lobe, the homos’ ability of visual perception gets better over the various stages from Habilis to Sapiens. They learn to make use of their eyesights for survival purposes, such as interpreting their surrounding environment using light in the visible spectrum reflected by the objects to catch sight of possible predators.

Brain Volume & Gyri


As mentioned above, the brain changes not just from apes to homos, but also within the homo series. Here, we look at the evolution of brain volume and gyri in hominids over the years. The Great Apes whom humans share a common ancestor with, consist of Chimpanzees, Orangutans and Gorillas that have an average brain volume which ranges from 400 to 500 cm3 . On the other hand, the average brain volume of the Homo Genus is approximately 1,000 cm3 . If we look at it independently, brain volumes of Homo Habilis, Homo Erectus and Homo Sapiens are 640 cm3 , 900 cm3 and 1,300cm3 respectively. It can be seen that as hominids progress and evolve into humans (sapiens), their brains get increasingly bigger. Apart from the change in volume, increase in brain gyri contributes to the overall growth in size as well. A gyrus refers to the raised surface of the brain as a result of brain folding activities. Due to the expansion of the frontal and parietal lobes, brain foldings increase and result in more brain gyri which eventually lead to a wider neocortex surface. The neocortex is known as the ‘thinking brain’; executive functions include rationality, sensory perception, generation of motor commands and in humans, language. Hence, the potential for speech production may have arose as early as the Homos days.  

Brain-Body Ratio

Brain-body ratio looks at how the brain size usually increases when the body size does. It has been hypothesized to be a rough estimate of the intelligence of an animal. Although it is fairly inaccurate in many cases to date, the relationship remains fuzzy and unanswered for. No doubt that as the homos evolve and become more human-like over the stages from Habilis to Sapiens, both body and brain sizes have had gradual increases. However, this phenomenon cannot assumably account for the higher mental capability of the homos over the years of evolution. The relationship of the brain to body ratio is not linear, which means that having a big body may not necessarily correlate to having a big brain, and vice-versa. Moreover, having a bigger brain has not been scientifically proven to be smarter. Hence, although Homo Sapiens have a greater brain-body ratio as compared to Homo Habilis and Erectus, it may be possible that the latter have had a higher Intellectual Quotient (IQ) back in the days. This is something left unfigured and unknown as it is almost impossible now to trace back.

Although the myth of how having a bigger brain means having better mental ability remains to date, but what else could have possibly been contributing to humans’ increasing IQ over the years if not for a bigger brain? Perhaps increased brain connectivity between the synapses? If so, do you think having a bigger brain allows for better creativity and innovation? Food for thought!

2.2 Body Structure

Other than the crucial biological evolution in the brain, physical body changes are undeniably obvious as well from the stages of Habilis to Erectus to that of us, Sapiens today. Body structure consists of many anatomies but in this section, emphasis will be placed only on three main areas. This is because the biological and physical evolution of these parts eventually give rise to evident features that are significant to non-verbal communications.


The lumbar curve forms part of the spine and is an uniquely human feature. Non-human primates such as Gorillas, Orangutans and Chimpanzees do not have this spinal part. Its development started in the homo days and became a significant feature later that contributes greatly to the phenomenon of bipedalism (how living organisms are able to walk and operate on two legs). After the growth of the lumbar curve in homos, bipedalism did not take place immediately as it was in the form of a C-shaped spine. It was only over time that this C-shaped curve progressively undergo a decrease in degree of forward bending which eventually establishes a permanent S-shaped curvature, something that all of us have today. Homo Habilis, also known as the ‘Handy-man’, was discovered to have operated on two limbs but not in a total upright manner. It was until the stage of Homo Erectus where the lumbar curve turned upright, giving him the name of ‘Upright-man’. This S-shaped curvature helps to bring the center of gravity closer to the body’s midline and above the feet, allowing better balance for bipedalism. It provides maximum mobility and at the same time, enable hands to be free of restriction and be used for other survival purposes such as picking fruits and attacking foes.


Archaeologists have found that the feet of Homo Habilis are similar to that of ours. Over time as Habilis evolved into Erectus and finally to Sapiens, their feet went through changes in length, size and serving purposes. The feet length gets increasingly longer while the heels become larger in size as the homos turn more human-like. This change allowed for better support and balance as the weights of these homos get increasingly heavier along the timeline of evolution. This probably explains why the homos were able to run and chase after preys later in the days after bipedalism was established. Also, toe adduction allowed the big toe to move progressively nearer to the other toes and eventually be in line with one another. The feet of non-human primates often have their big toe far apart from the others to allow activities such as clinging on to tree trunks. However, this function became redundant over time as bipedalism came into play. The key purpose of feet had changed from grasping to supporting bipedalism while toe adduction helped with the handling and managing of weight for better stability.


Similar to how the feet encountered a change in key serving purpose, the hands of homos evolved physically as well to allow for more general uses. Back when homos were more distant from human-like, hands were primarily used for specific reasons such as fruits and tools grabbing. Fingers were stiff and fixated as the bones were bent in a slightly forward curve. Evolution decreased this degree of curve gradually. By the stage of sapiens, fingers could be fully stretched out in a straight manner and bent to any degree as and when is needed. Flexibility of the hands increased and the possible uses of them varied greatly over time, from specific functions mentioned earlier to general ones (i.e. whatever humans can do with their hands now). Actions such as thumbs up, counting with fingers and pointing are made possible given the evolution of the hands. Also, both the palm size and length of fingers increased as the homos become more human-like. Enlarged hands are more muscular and provide higher energy level to serve survival purposes such as creating stone tools to prepare food or defend against enemies. Emergence of all these changes complemented the phenomenon of bipedalism; maximizing the effective usage of the hands for other purposes while operating on two limbs.

2.3 Facial Changes

Comparing within the Hominids family, the face is probably the most distinctive difference. Even within the Homo Genus family, facial changes have been prominent across the various stages of evolution particularly changes in the Jaw, Facial Hair and Nose. The changes in these areas are more evident and explained for by archaeologists as compared to areas like the ear, depth of eyes and etc.


From Habilis to Erectus and eventually Sapiens, the size of the jaw and teeth had decreased greatly. Although facially habilis did not show high resemblance to humans, he definitely looked pretty different to non-human primates. Known as the handy-man, habilis is popular for his tools-making expertise. He may have made good use of tools to prepare softer food, resulting in a reduction of jaw bone size over the long term due to the decrease in usage of oral muscles. The progressively smaller jaw caused the oral cavity to decrease in size, potentially allowing speech production in humans later on as a smaller cavity allows for better muscular control. With more control, air flow that arises from the lungs can be constricted in the oral space to produce sounds. Hence, speech being a uniquely human feature, is likely to have developed as a result of the biological changes in the jaws of homos. Not only that, mouths got increasingly less rounded, growing away from the uniquely primate feature. Faces turned increasingly gracile over the years with elongated foreheads and chins becoming more prominent on the face.

Facial Hair

It is a known fact that the loss of body hair resulted in the human form today, greatly diversified from our non-human primate cousins who are covered in thick layers of hair. The appearance of Habilis resembled that of a caveman; unkempt looking with both the face and body covered in hair. Evolution to Erectus took a turn when fossils reflected that he had been running after animals and hunting down preys. This stage marked the beginning of running in the homo family, and also the start of the loss of facial and body hair as an entirely new system of keeping cool had to be established to prevent fatal overheating from strenuous activities. The need for the skin to be directly exposed to air arose so that evaporation of sweat could happen. This process was crucial to keeping bodies cool. Hence, facial and body hair started to drop for skin-air exposure. By keeping cool, the body could be spared from unnecessary energy burning efforts to lower its temperature. This in turn facilitated energy conservation, vital for the homos to travel for a longer time and distance. Should hair loss not have taken place, the homos would have struggled with keeping their body temperatures low; travelling far would have been an issue then.


The last biological change would be the evolution of the nose area. Our non-human primate cousins have small and flat noses. Divergence from them gave homos progressively prominent and protruding noses with less flaring nostrils. The receding jaw structure mentioned earlier also caused an impact on the nasal area. The presence of a flatter nose back then was to serve the purpose of more effective inhaling, but this purpose became unnecessary over time as the homos found survival and hunting methods that did not require so much of this function (eg. Creating lure traps to capture preys instead of chasing after them). Instead, the nose exapted to act as a radiator. It increased in size and protruded over time with the nose passageways turning narrower to help the body lose heat. Such nostrils had the function of moistening and warming air that passes through the nose before entering the lungs, effectively reducing water and heat loss during exhalation. The evolution in the nasal area is particularly important as breathing is involved. With biological features that aided regulated breathing and heat loss, the homos stood a higher chance in survival.

So, you must be curious how these biological evolutions in hominids relate to non-verbal communications right? Let us bring you through the next section to share with you how the features discussed earlier contribute to NVC!

3. Non-verbal Communications

With the emergence of bipedalism, the early hominins developed more sophisticated ways to gesture to one another than their immediate primate ancestors. As brain size increased and migration out of Africa begin, it led to the creation of more complex and combined use of gestures to form and make sense of meanings.

3.1 Kinesics

Kinesics is the interpretation of body motion communication such as facial expressions and gestures, nonverbal behavior related to movement of any part of the body or the body as a whole.


Pongo: Orangutans

A study done across 3 European zoos found that shows the apes have at least 25 signals or gestures for ‘I want to play’, for example – ranging from a back roll and somersault, to a yank of their hair or a bite of the air, or clowning gestures like playing with their faces and placing objects on their heads. Brushing with a hand means they want something to stop, while embracing and pulling another ape at the same time means they want it to walk with them. These are very similar habitual or gestural acts that are done by the modern human as well.


The gorilla’s most famous gesture is the chest beat, standing on two legs and hitting the chest alternately with their open hands, rather than their clenched fists – as portrayed in films. It is to show off his size and demonstrate dominance and strength. Gorillas are often quiet and any sounds they do make are very soft, body language is often just as important. If a gorilla hears something that it suspects to be dangerous, it will not immediately give alarm calls, and instead it will sit quietly and observe, with a body position that is hunched and lowered back to avoid detection.

Pan: Chimpanzees

Scientists have found out that wild chimps communicate 19 specific messages to one another with a “lexicon” of 66 gestures. Although gestures are identified, they often deliver ambiguous messages and meaning, where a grab or touch may mean “Stop that” or “Climb up”. Only leaf clipping has been confirmed – where a chimp takes obvious small bites of the leaf to elicit sexual attraction.

Homo Genus

It seems not too far-fetched to suppose that the cerebral asymmetry of function developed in conjunction with the asymmetric activity of the two limbs during tool use, with the left hemisphere becoming the hemisphere specialized for sequential limb positioning/ movement (precise motor control). Thus when a gestural system was employed, it would presumably also be controlled primarily from the left hemisphere. It is clear that the employment of most tools requires the asymmetrical use of both arms, in modern man context, it is systematic where  one hand (usually the left) acts as the stable balancing hand, and the other (right) acts as the moving hand for actions like chopping or hitting.
Researchers have also found out that neurons in the premotor cortex of the primate respond when it makes grasping movements or gestures with their arms or hands. Also dubbed as “mirror neurons”, they also respond when the animal observes another animal making movements, thus mapping the perceived gestures into produced gestures. This also brings us to understand the manipulative nature of primates.

Modern-day Humans

At first, facial and manual gestures would have been accompanied by grunts (no speech), but in modern humans vocal language is accompanied by manual gestures to add meaning/ support the message they want to convey. We often include manual gestures to substitute spoken particles/ words (i.e. He’s completely (gone crazy) – using a spiral twisting manual gesture near the head to indicate crazy).

Facial Expressions

It is likely that the face increasingly became more involved in gesturing, along with the higher sophistication of tools usage, creation and manipulation, which heavily occupied the hands. The development of facial muscles and thinner jaw structures also enabled for more flexibility in creating such expressions. Facial gestures can also be associated with vocalization acts and sounds like lips-smacking, teeth chattering and whistling (to display hunger, looking for fun).

Body Language

Discovered by archaeologists, there is evidence that there is a right-hand preference in wielding tools such as clubs, stone and bone tools. The manual gesturing communicative system could possibly be built on manual skills associated with tool use, where they had the precision of upper limb movement control, which made gesturing possible. The development of the spines and bone structures also allowed for more sophisticated movements and postures as the homo developed.

3.2 Oculesics

Oculesics, a subcategory of body language, is the study of eye movement, eye behavior, gaze, and eye-related nonverbal communication. As a social or behavioral science, oculesics is a form of nonverbal communication focusing on deriving meaning from eye behavior. It must be noted that culture plays a role in oculesics for modern humans, where the necessity of eye contact and the civility it provides differs greatly across cultures (i.e.  In an Asian culture, direct eye contact may be considered rude, but in a Westernized or American culture, lack of eye contact shows disinterest or disrespect).

Eye Contact

There are two levels of eye contact – direct & indirect. The use of it can indicate interest, openness, and if with intensity, it can be perceived as a form of hostility. The lack of eye contact at the same time may deliver a sense of disinterest or lack of attention (be it the listener or speaker).

Eye Movement

The movement occurs voluntarily/ involuntarily. It can include the change of eye direction and focus, or following objects with the eyes. The two typical directions would be the eyes up and eyes down movements, where the former indicates the act of thinking, recalling and perhaps even irritation in the modern context (eye roll). The latter demonstrates a sense of fear, submission or guilt.

Pupil Dilation

This is the pupillary response to the change of size in pupil. This change happens at the appearance of real or perceived new objects of focus, and even at the real or perceived indication of such appearances. It can often be regarded as an indication of attraction/ sexual desire as well.

Gaze Direction

The last dimension deals with voluntary and involuntary communication through the eye. It typically indicates interest in whatever object that is being gazed at, delivering a “I want that” message.

3.3 Joint Attention

Joint attention (JA) or shared attention is the shared focus of two individuals on an object. It is achieved when one individual alerts another to an object by means of eye-gazing, pointing or other non-verbal methods and verbal indications. An individual gazes at another individual, points to an object and then returns their gaze to the individual.

Triadic JA

This is the highest level of joint attention and involves two individuals looking at an object. For an instance to count as triadic JA, each individual must understand that the other is looking at the same object and be aware that there is an element of shared attention between himself and the other. The process is marked by the individual looking back to the other individual after looking at the object. Individuals who engage in triadic JA must understand both gaze and intention to establish common reference.

Gaze refers to one’s understanding of the link between mental activity and the physical act of seeing. Intention refers to one’s ability to understand the goal of another person’s mental processes. When individuals understand that others have goals, intentions, and attentional states, they are able to enter into and direct another’s attention.

Dyadic JA

Next up, this is a conversation-like behavior that individuals engage in. This is especially true for human adults and infants, who engage in this behavior starting at two months of age. Adults and infants take turns exchanging facial expressions, noises, and in the case of the adult, motherese and singing. Definitely, our non-human primate cousins engage in dyadic joint attention with their children as well.

Shared JA

Shared gaze occurs when two individuals are simply looking at an object, and it is the lowest level of joint attention. As gaze increases in complexity, individuals are better able to discriminate what others are referring to. Gaze-following reflects an expectation-based type of orienting in which an individual’s attention is cued by another’s head turn or eye turn. Individuals are motivated to follow another’s gaze and engage in joint attention because gaze is a cue for which rewarding events occur.

4. Conclusion

This is a bizarre, challenging yet daunting entry for sure. How was it possible for us (unless we time-travel) to base and investigate on our topic of non-verbal communication if there isn’t any visual traces or even written records 2 million years ago? From a pragmatic perspective, we are fully aware of the lack of consensus regarding nonverbal communication of our homo ancestors, mainly due to restrictive guesses and tentative conclusions in relevant researches. Consequently, this study has endeavored to account for this unfortunate discontinuity by investigating biological evolution – be it visible changes of spine, hands, feet and face, or those occurring in our ancestor’s brain (lobes, volume, gyri, body ratio), against three major components of NVC such as kinesics, oculesics and joint attention.
However, as mentioned above, many established literatures were based on speculative premises and this entry is not an exception. We drew parallel with other hominids such as gorilla, pan and pongo genuses – to enrich our analysis and perhaps discover an analogous element in NVC development among these cousins. Regardless, the purpose of this entry takes root from the undeniable fact that there is a concealed linkage between hominids (especially homo genus) and nonverbal communication – with this chapter ultimately serving as a pioneering bridge for future researches.

5. References

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