Mirror neurons are a class of neuron 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 I below.

 Figure I: 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.