For the past century, Australopithecus was considered the starting point in the evolution of chimpanzees and Homo Sapiens. Although the difference between the first discovered specimen and species of modern chimpanzees were significant, due to a lack of evidence, evolutionary theory was led in a wrong direction, as many researchers and scientists tried to explain how did Australopithecus evolve into Homo Habilis in a relatively short amount of time. Both changes, from the evolutionary perspective, seemed sudden and abrupt, which suggested the presence of a so-called “missing link,” which would answer these questions and fill the space between Pan Troglodytes and Australopithecus (White et al. 2015). The discovery of Ardipithecus Ramidus in 1994 managed to fill out the void between these two species, as the newly-discovered species demonstrated some similarities with the Hominids, such as reduced sizes of canines and the anatomy of molars, while retaining several traits associated with chimpanzees, such as the elongated toes for tree-climbing and grabbing unto branches (White et al. 2015). Other differences included the appearance of the cranium, as well as the alleged capability of a wider range of sounds and volumes produced as a means of communication. The purpose of this paper is to analyze Ardipithecus Ramidus and its capacity for speech in comparison to communication methods in chimpanzees in order to perceive evolutionary changes that took place.
The Connection between Language and Anatomical Development
A species’ capability for communication largely revolves around two anatomical factors – the capability of the body to produce a large variety of distinct and recognizable sounds in order to provide information from a distance, as well as the mental capacity to imbue sounds with meaning and interpret the sounds produced by other members of their species. The former is largely influenced by the organs found within the vocal tract, the strength, and flexibility of larynx muscles and vocal chords, as well as the construction of the throat, tongue, and teeth. The latter is defined by the size of the brain as well as the capability for complex cortical actions and assessments in addition to the capacity for expressing emotion (White et al. 2015). The purpose of the following sections is to analyze Pan Troglodytes, Ardipithecus Ramidus, and Australopithecus in order to determine any similarities and differences in their capacity for language based on the criteria mentioned above.
Chimpanzee Capabilities at Communication
Out of all non-human species, the chimpanzee has the closest genetic makeup when compared to humans. Predispositions towards the development and use of speech in chimpanzees are dictated by the social nature of the species’ existence. They use a wide range of sounds and gestures in order to communicate information and warn each other of danger. Other species, such as the Great Ape and Orangutan, do not have the same capacity and range of speech due to their relatively slow-paced and solitary lifestyles. According to Taglialatela et al. (2015), chimpanzees are capable of multimodal communication, which involves sounds, gestures, and facial expressions. They are also capable of complex cortical activity, which is one of the prerequisites towards using language as means of communication.
Chimpanzees have demonstrated a limited capability to understanding human speech as well, as was proven in numerous experiments (Taglialatela et al. 2015). However, their reliance on multimodality in order to convey basic information is the result of limitations of their vocal apparatus. As stated by Taglialatela et al. (2015), chimpanzees are capable of repetitively replicating over a dozen of basic sounds, and are capable of enhancing their volume depending on the distance between them and other members of their tribes. However, their laryngeal muscles lack the strength, flexibility, and fine control of these muscles as well as local chords. Their lips and teeth are not optimized for talking or producing a more varied palette of sounds. The chimpanzee’s elongated craniofacial structure poses additional difficulties in extending their vocal range (Taglialatela et al. 2015). Although chimpanzees possess the mental capacity for understanding complex systems of communication, they are held back by their own physiology.
Vocal Capabilities of Ardipithecus Ramidus
The research performed by Clark and Henneberg (2017) provides evidence of impressive vocal capabilities of the Ardipithecus Ramidus species, which exceed those of any non-human primate. The provided analysis states that the physical and mental evolution of the species in comparison to its predecessors – the Pan Troglodytes, was motivated by the increased necessity for socialization in the context of the palaeoecological environment of swamps and forests of the late Miocene – Early Pliocene periods (Clark & Henneberg 2017).
One of the primary factors that affected the development of vocal capabilities in Ardipithecus Ramidus was the adoption of a more erect posture when compared to their nearest predecessors. The researchers argue that this factor, along with the increase of overall brain mass and reduction of facial and jaw length provided increased range of sounds. Because of these changes, the larynx, which is the main part of the body responsible for vocal abilities of a species, was located deeper inside the neck, which in turn reinforced control by providing extra muscles to affect it (Clark & Henneberg 2017). The more erect posture lead to the development of cervical lordosis previously unseen among the remains of Pan Troglodytes, which in turn allowed for greater larynx and neck mobility (Clark & Henneberg 2017). The increase of control over the larynx, thus, allowed Ardipithecus Ramid to express a larger variety of sounds, which in turn enhanced its ability to socialize with other group members (Clark & Henneberg 2017).
Craniofacial morphology changes that took place in the transition were also important. Evidence on language evolution indicates a distinct correlation between the appearance of a flex cranial base and shorter jaw in conjunction with the overall skeletal configuration and the increased importance in socializing and mating rituals and behavior, as the language allowed mediating issues vocally rather than physically (Clark & Henneberg 2017). While older sources associate the appearance of first vocal languages and communication methods with the Australopithecus, the physiology of Ardipithecus Ramid indicates that the transformation occurred much earlier.
Lastly, Ardipithecus Ramid shares a similarity to Australopithecus afarensis in the overall shape of the hypoglossal canal – a structure that has been recently used in modern anthropology as a means of determining the capability for speech. Its differentiation in Ardipithecus Ramid from Pan Troglodytes lies in shared traits of canals with the Australopithecus and Homo genomes, namely in the topography of prevertebral muscle as well as at the insertion sites (Kimbel et al. 2014). The similarities make it possible to conclude that Ardipithecus Ramid also possessed the capability of speech and that their language was more similar to those of Australopithecus rather than with to those of chimpanzees, whose hypoglossal canals are defined by deep concavities and anterolateral prominences (Kimbel et al. 2014).
To summarize, the increase in vocal capabilities of Ardipithecus Ramid, when compared to Pan Troglodytes, was largely motivated by a more erect posture in combination with a beneficial cranial morphology, both of which were likely motivated by the environment that the species resided in. The necessity for a more socialized and organized existence as a means of survival trigger a gradual development of the non-human primates into Ardipithecus Ramid.
On Further Evolution of Australopithecus
Australopithecus is suspected to be capable of speech largely due to their cranial and skeletal morphology in combination with archeological findings of primitive tools used by the species to hunt and gather fruits. The evolution of these tools indicates the growth in skill, which could be achieved only through teaching and passing information from one individual to another, thus improving on previous practices, which would be impossible without a way of relaying information past the mimicry of gestures and expressions (Kimbel et al. 2014). In addition, Australopithecus possessed even more defined bipedalism than the Ardipithecus Ramid, as well as better-evolved tools for facilitating a more informative and complex language. Another difference between the two species lies in changes of the ear canal, which allowed Australopithecus to better perceive the sounds made by other members of their species (Kimbel et al. 2014).
Conclusions
This paper illustrates the gradual evolution of speech organs from Pan Troglodytes to Ardipithecus Ramid and Australopithecus, indicating that the evolution of the species was followed by increase in socialization skills and the capacity to emanate and understand a greater multitude of sounds, which were used not only to express basic emotions but also to warn others of danger, settle mating disputes, and transmit knowledge of skills. These findings further support the theory that Ardipithecus Ramid is indeed the missing link between Pan Troglodytes and Ardipithecus Ramid.
Reference List
Clark, Gary, and Maciej Henneberg. 2017 Ardipithecus Ramidus and the Evolution of Language and Singing: An Early Origin for Hominin Vocal Capability. HOMO – Journal of Comparative Human Biology 68(2):101-121.
Kimbel, William H., Gen Suwa, Berhane Asfaw, Yoel Rak, and Tim D. White. 2014 Ardipithecus Ramidus and the Evolution of the Human Cranial Base. PNAS 111(3):948-953.
Taglialatela, Jared P., Jamie L. Russel, Sarah M. Pope, Tamara Morton, Stephanie Bogart, Lisa A. Reamer, Steven J. Shapiro, et al. 2015 Multimodal Communication in Chimpanzees. American Journal of Primatology 77:1143-1148.
White, Tim D., C. Owen Lovejoy, Berhane Asfaw, Joshua P. Carlson, and Gen Suwa. 2015 Neither Chimpanzee nor Human, Ardipithecus Reveals the Surprising Ancestry of Both. PNAS 112(16):4877-4884.