There have also been studies based on the evolution of human limbs compared with apes, which overall revealed that humans and apes share similarities in limbs development.
The development of limbs is perhaps associated with active movements, that is, limbs are shaped in accordance with particular body movements in an evolutionary way. Therefore, human and primate hands control movement initially from the head such as mouth for attack, food preparation for chewing, defence, and so forth. This suggests that human facial expressions, vocalisation, and gestural language assume some sort of instrumental evolution of both human and hominid hand and face.
In addition, body motion is a component of gestural communication. During the evolution of human development, man begins to use arms and hands to hold things. The phases of a child’s life have also been demonstrated, how this development occurs from grasping actions transitioning into instinctive pointing actions (Wundt, 1911, cited in Sankaran, ca. 1939-40, p.231)There are also limitations of the gestural theory, which puts constraints on various ideas. For example, the use of gestures in darkness by our hominid ancestors may have been impractical and difficult to interact at a distance, particularly in outdoor activities such as hunting; therefore, the progression of language was contingent on the use of vocal sounds. This is what prompted man to mimic animal sounds such as bird cries, resulting in man creating articulate sounds (Monboddo, 1774, cited in Wells, 1987, p. 20).
The notion of vocalisation may have created an initial pathway in which vocal language overruled gestural language in this sense. The action of imitating embraces different meanings (Gass, 2006). Furthermore, some theories stress the lack of these language-like aspects present in primate gestural or facial communication as a means of constraining opposing theories.
In this vein, gestural language can be labelled as a poor interactive device (Tomasello, 2008). The gestural theory appears to attract more attention out of the many glottogonic hypotheses that exist, and features more strengths than weaknesses. The discovery of the mirror neuron system also offers further support.
A group of Italian scholars in the early 1990s had located distinctive neurons in a monkey’s brain, which revealed a unique correlation between gestures and homologous areas of language production. When the monkey performed a specific movement, these neurons discharged (di Pellegrino et al., 1992). This led to similar research, which identified other sectors of the brain relating to mirror neurons, such as Broca’s area. Brain research may propose that gestural language was the main form of communication than vocal language (Hewes, 1973). It is apparent in both humans and chimpanzees that both species exhibit right-hand gestures than left-hand gestures during speech (Kimura, 1973; Hopkins el al., 2005). Further evidence posits that conventional sounds in languages were led by the concept of language of nature including gestures, onomatopoeic sounds, and emotional calls (Herder, 1877, cited in Wells, 1987, p.
31).It is clear these theories of language origin depend on empirical evidence of primate interaction to a degree as a crucial line of argument. Though for centuries the vocal theories have been advocated by many scholars, it did not receive enough attention. With the expansion of research methods employed, yet recent studies based on humans and mammals, specifically primates, have provided experimental support for the significant contribution of gestures in language evolution.
The notion of vocal sounds is not a strong substance of language, and gestures must be considered to reflect on how language occurred. Furthermore, language can be regarded as a multimodal system. If language was non-existent, using different techniques to convey messages would be normal. For example, if a person wanted to convey a message of sorrow, using a facial expression would be fitting. And if they wanted to convey an animal sound they had heard, they may lean towards vocalisation to imitate the sound.
Speech is instantly accompanied by gestures to communicate without learning (Iverson & Goldin-Meadow, 1998). Without gestures it would merely be impossible to converse and express feelings, therefore the gestural theory of language origin seems to be more conceivable in the sense that it is efficient and adopts a much more realistic perspective on language evolution as opposed to the vocal theory.
