7.1. The cognitive niche hypothesis
Following our discussion on the general physical evolution of humans in the previous section, we now move on to an examination of how language are processed and understood. The cognitive niche hypothesis first advanced in Pinker & Bloom (1990) and later revised in Pinker (2010), is a consolidation of the human traits that distinguishes the natural language from other forms of animal communication. According to this framework, humans possess an innate mental state that provides them the basis for acquisition and knowledge of grammar, and to share it among themselves.
This cognitive niche includes the prerequisites of possessing a theory of mind, and also a need for social interaction. A number of scholars have proposed that the roots of theory of mind may be traced to mirror neurons and also the episodic memory in the primate brain, before it evolves into a distinctively human trait.
Though mirror neurons and episodic memory are found to be of separate systems in the human brain, both are able to give us a broader contexts for understanding the complementary functions of the human language and mind.
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7.2 Mirror neurons
Mirror neurons are a class of neurons which are activated as an animal executes a movement via motor control and when they imitate another individual’s (possibly conspecific) behaviour (Kilneremail & Lemon, 2013). These mirror neurons are hypothesized to be an adaptation mechanism for the understanding of actions, imitation-learning, and of associative learning. Perception and the genetic basis of human vocal imitation are suggested to be linked by mirror neurons similar to that of the monkeys in a way that is connected to the reciprocity of linguistic signs. This hypothesis is supported by some homologies discovered between the Macaque monkey’s premotor area F5 and also the human Broca’s area, as seen in Figure 5 below.
Figure 7: Mirror Neurons in the premotor cortex of macaque monkeys (indicated by red and yellow areas in A above) and in the right superior temporal sulcus of humans (indicated by red and yellow areas in B above)
Studies with Magnetic Resonance Imaging (MRI) have discovered that some cortical areas of the human brain like the inferior frontal cortex (near to the Broca’s area) are homologous to the monkey mirror neuron system. As the Broca’s area is thought to be one of the most language centered regions of the brain, one possible hypothesis is that the human language may have been evolved from the system of mirror neurons. The distinction of the mirror neuron system between monkeys and humans is that the human mirror neurons are able to be activated by linguistically related actions like reading and listening.
Human children have the ability to vocally repeat pseudowords via echolalia and speech shadowing. Such speech repetition and imitation not only helps the children to acquire new sets of vocabulary, this process of language acquisition via speech repetition is instinctive and can occur without comprehension and understanding. This suggests that the development of mirror neurons is a feature associated with a strong genetic predisposition of humans, favored by natural selection.
It is plausible that genetically pre-programmed mirror neurons was a result of a gradual process of language evolution. Improvements in cognitive mechanisms could have been selected for the mirror neurons’ ability to recognize, imitate and familiarise with complex actions. This function may account for the inﬂuence of prefrontal cortex and ventral pathways. Though there may not be concrete evidence that mirror neurons are a genetic adaptation specifically humans’, it remains that genetics may dictate the learning process of neurons and not just what they learn.
Alternatively, there is also the theory that mirror neurons are a result of associative learning instead of evolutionary adaptation. It suggests that the properties of the mirror neurons are a product, not of a genetic predisposition, but of the general processes of associative learning like conditioning procedures. The associative hypothesis conjectures that mirror neurons can also be found in other non human species. For instance, the quality of speech sounds known as formants are perceivable by many vertebrates such as primates and birds. The ability to accurately distinguish formants specific to different individuals of their species suggests that mirror neurons may also be present in animals. Specifically, a related example is the honeybees. The honeybees are able to make use of associative learning to distinguish individual human faces. When the honeybees are placed in an environment whereby the recognition of human faces are crucial, associative learning are optimized for the foraging behavior of the honeybees. Given that human faces were not originally part of the environment where the honeybee nervous systems evolved, associative learning is not an adaptation for face discrimination in honeybees (Cook et. al, 2014).
However, the associative learning is not sufﬁcient to account for the development of mirror neurons. For instance, genetic predispositions interacts with associative learning; the associative account is unable to justify the reason why some behaviors are learnt more easily than others. Genetic predispositions hence may interact with associative learning to produce efficiency in language learning. Many experiments have also shown that human infants are inclined to imitate humans as opposed to non human actions (Bertenthal, 2014). Thus, associative learning is necessary but not an sufﬁcient enough explanation for mirror neuron development.
It remains that the discovery of mirror neurons have result in breakthroughs in the gestural theory of speech origin. Mirror neurons in humans facilitates a direct communication between interlocutors. The actions communicated by an individual can be understood by an observer as it is able to elicit the same motor representation in their parieto-frontal mirror system. It is proposed that the mirror neurons are the basic mechanism where human language evolved. This is because it can be used to explain one of the fundamental difficulties for understanding language evolution- how messages conveyed can become valid for both the interlocutors.
7.3 Episodic memory
According to Tulving (1972), episodic memory is an important cognitive development unique to humans. Controlled by the prefrontal medial temporal regions and posterior regions such as the posterior cingulate and retrosplenial cortex, it refers to the ability of humans to remember and re-experience past events (episodic memory) and to anticipate future events. Concerned with conscious recollection of specific past experiences, episodic memory allows humans to ‘travel’ mentally in time is important for encoding the ability for learning and retaining language skills.
This ability may have co-evolved as an adaptation with the genus Homo millions of years ago, as it allows the documentary of important historical and environmental events (cave paintings etc) , giving humans the ability to analyse and compare present, past and future scenarios.
Some features of the grammatical language may have also been derived from this pressure to communicate the timing of events (displacement) so as to strategize and enhance group survival in difficult terrains and environments. Thus this communicative cooperation amongst humans with regards to future references and planning of events may have co-evolved with symbolic communication systems.
Episodic memories are also generative, thus resulting in the productivity and creative attribute of human language. When strategizing for future events, humans have the capacity to remember and compare the different scenarios from their store of semantic concepts and episodic memories (Corballis, 2010).
Another point to note is that, more recent research has shown that there are at least some animals, notably a few primates and corvids, that exhibits the potential for episodic memory, and thus it may not be an aspect that is unique only to humans. However, more extensive research is needed to support this theory.