This article argues that mirror neurons originate in sensorimotor associative learning and therefore a new approach is needed to investigate their functions. Mirror neurons were discovered about 20 years ago in the monkey brain, and there is now evidence that they are also present in the human brain. The intriguing feature of many mirror neurons is that they fire not only when the animal is performing an action, such as grasping an object using a power grip, but also when the animal passively observes a similar action performed by another agent. It is widely believed that mirror neurons are a genetic adaptation for action understanding; that they were designed by evolution to fulfill a specific socio-cognitive function. In contrast, we argue that mirror neurons are forged by domain-general processes of associative learning in the course of individual development, and, although they may have psychological functions, they do not necessarily have a specific evolutionary purpose or adaptive function. The evidence supporting this view shows that (1) mirror neurons do not consistently encode action “goals”; (2) the contingency- and context-sensitive nature of associative learning explains the full range of mirror neuron properties; (3) human infants receive enough sensorimotor experience to support associative learning of mirror neurons (“wealth of the stimulus”); and (4) mirror neurons can be changed in radical ways by sensorimotor training. The associative account implies that reliable information about the function of mirror neurons can be obtained only by research based on developmental history, system-level theory, and careful experimentation.

Arbib offers a coherent proposal of how the brain has evolved to become language-capable. Integral to the argument are mirror neurons, cells discovered in macaque brains with interesting firing patterns, and studies on gestural communication of great apes. Here, I first discuss some complexities of the recent mirror neuron literature, which suggest that ‘mirroring’ may be an ontogenetically acquired, not an evolved, feature of neurons. Second, it is now clear that chimpanzee vocal behaviour is strongly mediated by social variables, and that individuals can use vocalisations to persuade and inform others, facts that have implications for gestural theories of language evolution. I conclude with discussing research most needed for making progress in understanding how human language has evolved.