Challenges for extending the mirror system hypothesis include mechanisms supporting planning, conversation, motivation, theory of mind, and prosody. Modeling remains relevant. Co-speech gestures show how manual gesture and speech intertwine, but more attention is needed to the auditory system and phonology. The holophrastic view of protolanguage is debated, along with semantics and the cultural basis of grammars. Anatomically separated regions may share an evolutionary history.

Mirror systems must be supplemented by a planning capability to allow language to evolve. A capability for creating, storing, and executing plans for sequences of actions, having evolved in primates, was applied to sequences of communicatory acts. Language could exploit this already-existing capability. Further steps in language evolution may parallel steps seen in the development of modern children.

It is often claimed that the discovery of mirror neurons supports simulation theory (ST). There has been much controversy about this, however, as there are various competing models of the functional contribution of mirror systems, only some of which characterize mirroring as simulation in the sense required by ST. But a brief review of these models reveals that they all include simulation in some sense . In this paper, I propose that the broader conception of simulation articulated (...) by neo-empiricist theories of concepts can subsume the more specific conceptions of simulation presented by ST and by these other models, thereby offering a framework in which each of these models may play a role. According to neo-empiricism, conceptual thought in general involves simulation in the sense that it is grounded in sensory, motor, and other embodied systems (Barsalou, Behavioral and Brain Sciences , 22 , 577–609, 1999 , Philosophical Transactions of the Royal Society of London: Biological Sciences , 364 , 1281–1289, 2009 ; Barsalou et al., Trends in Cognitive Sciences , 7 (2), 84–91, 2003 ; Prinz 2002 , Mind & Language , 25 (5), 612–621, 2010 ; Glenberg and Robertson, Journal of Memory and Language , 43 , 379–401, 2000 ). Crucially, the term “simulation” here refers not to simulations of a target agent’s experience in the sense endorsed by simulation theory but to the activation of sensory, motor, affective, and introspective representations. This difference does not entail that neo-empiricism must be in competition with ST—indeed, I will propose that ST can be embedded as a special case within neo-empiricism. (shrink)

We focus on the evolution of action capabilities which set the stage for language, rather than analyzing how further brain evolution built on these capabilities to yield a language-ready brain. Our framework is given by the Mirror System Hypothesis, which charts a progression from a monkey-like mirror neuron system (MNS) to a chimpanzee-like mirror system that supports simple imitation and thence to a human-like mirror system that supports complex imitation and language. We present the MNS2 model, (...) a new model of action recognition learning by mirror neurons of the macaque brain and augmented competitive queuing, a model of opportunistic scheduling of action sequences as background for analysis of modeling strategies for simple imitation as seen in the great apes and complex/goal-directed imitation as seen in humans. Implications for the study of language are briefly noted. (shrink)

Four distinct models of the functional contribution of mirror neurons to social cognition can be distinguished: direct matching, inverse modeling, response modeling, and predictive coding. Each entails a different way in which an agent's own capacities for action and affective experience contribute to understanding and/or predicting others' actions and affective experience. In this paper, the four models and their theoretical frameworks are elucidated, empirical data and theoretical arguments bearing upon each are reviewed, and falsifiable predictions that could help to (...) distinguish empirically among the models are proposed. (shrink)

Empathy is the phenomenal experience of mirroring ourselves into others. It can be explained in terms of simulations of actions, sensations, and emotions which constitute a shared manifold for intersubjectivity. Simulation, in turn, can be sustained at the subpersonal level by a series of neural mirror matching systems.

Mirror neurons and systems are often appealed to as mechanisms enabling mindreading, i.e., understanding other people’s mental states. Such neural mirroring processes are often treated as instances of mental simulation rather than folk psychological theorizing. I will call into question this assumed connection between mirroring and simulation, arguing that mirroring does not necessarily constitute mental simulation as specified by the simulation theory of mindreading. I begin by more precisely characterizing “mirroring” (Sect. 2) and “simulation” (Sect. 3). Mirroring results (...) in a neural process in an observer that resembles a neural process of the same type in the observed agent. Although simulation is often characterized in terms of resemblance (Goldman, Simulating minds: The philosophy, psychology, and neuroscience of mindreading, 2006), I argue that simulation requires more than mere interpersonal mental resemblance: A simulation must have the purpose or function of resembling its target (Sect. 3.1). Given that mirroring processes are generated automatically, I focus on what is required for a simulation to possess the function of resembling its target. In Sect. 3.2 I argue that this resemblance function, at least in the case of simulation-based mindreading, requires that a simulation serve as a representation or stand-in of what it resembles. With this revised account of simulation in hand, in Sect. 4 I show that the mirroring processes do not necessarily possess the representational function required of simulation. To do so I describe an account of goal attribution involving a motor mirroring process that should not be characterized as interpersonal mental simulation. I end in Sect. 5 by defending the conceptual distinction between mirroring and simulation, and discussing the implications of this argument for the kind of neuroscientific evidence required by simulation theory. (shrink)

Falk's hominin mother-infant model presupposes an emerging infant capacity to perceive and learn from afforded gestures and vocalizations. Unlike back-riding offspring of other primates, who were in no need to decenter their own body-centered perspective, a mirror neurons system may have been adapted in hominin infants to subserve the kind of (m)other-centered mirroring we now see manifested by human infants soon after birth.

Largely aided by the neurological discovery of so-called “ mirror neurons,” the attention to motor activity during action observation has exploded over the last two decades. The idea that we internally “ mirror ” the actions of others has led to a new strand of implicit simulation theories of action understanding[1][2]. The basic idea of this sort of simulation theory is that we, via an automatic covert activation of our own action representations, can understand the action and possibly (...) the goal and/or intentions of the observed agent. In this way motor “simulation” is seen as the basis for low-level “mind-reading”; i.e. for the ascription of goals and intentional mental states to others. The thought is that one, through mirroring simulations, can get beyond the observable behaviour to the hidden minds of others. I am questioning the idea of an exclusively “mirroring” role of the motor system in social perception, which is tacitly assumed in this sort of simulation theories. Is motor activity during action observation really primarily a simulation, a detailed “echo” of the others action? My point is not that we never simulate what we observe, but rather to question whether such processes are representative of the overall motor contribution to social cognition. More and more studies on the functional properties of mirror neurons and motor facilitation during perception points to a more complex role of the motor system in action perception. Recently, several proposals have been made attempting to reinterpret and critique the function of motor activity in social situations. I shall here briefly touch on a few of these and sketch parts of my own alternative “social affordance” hypothesis of the sensorimotor contribution to social perception. By way of these analyses I highlight how traditional discussions are marred by problematic theoretical assumptions. It seems to me that we need a thorough reinterpretation not just of mirror neurons and mirroring, but also of what we take motor and social cognition to be. In my view the details of the sensorimotor findings underline the need to move beyond the simplistic idea of the motor system as a unitary output system. In terms of social cognition I question the traditional focus on hidden mental states. I suggest that the motor contribution might have more to do with understanding the process of how others choose their actions, navigate the world and relate to others than with simulating specific actual actions or mental states. I conclude that low-level simulation theories, which see the motor role in social perception as passive “mirroring,” are faced with serious empirical challenges, and that the motor system serve a much more proactive and complex cognitive role in social perception and interaction than previously thought. But my claim is also that many empirical tensions have slipped out of focus due to entrenched theoretical assumptions. Narrow theoretical expectations have marked not only the interpretations but the research itself and I propose that we are in dire need of more studies of actual contextual and interactive social perception. (shrink)

We question the idea that the mirror neuron system is the substrate of social affordances perception, and we suggest that most of the activity seen in the parietal and premotor cortex of the human brain is independent of mirroring activity as characterized in macaques, but rather reflects a process of one's own action specification in response to social signals.

Mirror neurons are neurons which fire in two distinct conditions: (i) when an agent performs a specific action, like a precision grasp of an object using fingers, and (ii) when an agent observes that action performed by another. Some theorists have suggested that the existence of such neurons may lend support to the simulation approach to mindreading (e.g. Gallese and Goldman, 1998, 'Mirror neurons and the simulation theory of mind reading'). In this note I critically examine this suggestion, (...) in both its original and a revised form (due to Iacoboni et al., 2005, 'Grasping the intentions of others with one's own mirror neuron system'), and argue that the existence of mirror neurons can in fact tell us very little about how intentional attribution actually proceeds. (shrink)

Positing the importance of sensorimotor contingencies for perception is by no means denying the presence and importance of representations. Using the evidence of mirror neurons we will show the intrinsic relationship between action control and representation within the logic of forward models.

The mechanism by which humans perceive others differs greatly from how humans perceive inanimate objects. Unlike inanimate objects, humans have the distinct property of being “like me” in the eyes of the observer. This allows us to use the same systems that process knowledge about self-performed actions, self-conceived thoughts, and self-experienced emotions to understand actions, thoughts, and emotions in others. The authors propose that internal simulation mechanisms, such as the mirror neuron system, are necessary for normal development of (...) recognition, imitation, theory of mind, empathy, and language. Additionally, the authors suggest that dysfunctional simulation mechanisms may underlie the social and communicative deficits seen in individuals with autism spectrum disorders. (shrink)

A new class of visuomotor neuron has been recently discovered in the monkey’s premotor cortex: mirror neurons. These neurons respond both when a particular action is performed by the recorded monkey and when the same action, performed by another individual, is observed. Mirror neurons appear to form a cortical system matching observation and execution of goal-related motor actions. Experimental evidence suggests that a similar matching system also exists in humans. What might be the functional role of this matching (...) system? One possible function is to enable an organism to detect certain mental states of observed conspecifics. This function might be part of, or a precursor to, a more general mind-reading ability. Two different accounts of mind-reading have been suggested. According to “theory theory‘, mental states are represented as inferred posits of a naive theory. According to “simulation theory‘, other people’s mental states are represented by adopting their perspective: by tracking or matching their states with resonant states of one’s own. The activity of mirror neurons, and the fact that observers undergo motor facilitation in the same muscular groups as those utilized by target agents, are findings that accord well with simulation theory but would not be predicted by theory theory. (shrink)

Automated decision systems are often used to enforce legislation.As such, they have considerable regulating effects. These systemsregulate the behaviour of users and addressees mainly throughstandardization. This research classifies these systems intocategories according to which the regulating effects can bedescribed more clearly. Furthermore, this categorization resultsin a better understanding how problems encountered with atpresent can be avoided in the future. Many problems result fromthe way the development process has been organized. It turns outthe development process can be divided according (...) to the time thesystems are developed with regard to the legislation they aim toenforce. Present procedures lack good monitoring of thedevelopment process. To this end, legal procedures are needed toensure that a legally correct product will be made, partiesinvolved should change their tune, system developers should bemore concerned with the legal status of the system and thelegislator should be actively involved in the development of thesystem. Moreover, an ex ante-evaluation should notice thepossible regulating effects caused by the system to ensure acorrect balance of the pros and cons. It should be ensured thatthese systems are effectively put to control. Transparency isindispensable. (shrink)

Phantom limb experiences demonstrate an unexpected degree of fragility inherent in our self-perceptions. This is perhaps most extreme when congenitally absent limbs are experienced as phantoms. Aplasic phantoms highlight fundamental questions about the physiological bases of self-experience and the ontogeny of a physical, embodied sense of the self. Some of the most intriguing of these questions concern the role of mirror neurons in supporting the development of self–other mappings and hence the emergence of phantom experiences of congenitally absent limbs. (...) In this paper, we will examine the hypothesis that aplasic phantom limb experience is the result of an ontogenetic interplay between body schemas and mirror neuron activity and that this interplay is founded on embedding in a social context. Phantom limb experience has been associated with the persistence of subjective experience of a part of the body after deafferentation through surgical or traumatic removal. We maintain that limited association is inconsistent with the extent to which phantom limb experience is reported by aplasic individuals. (shrink)

It is now generally accepted that the motor system is not purely dedicated to the control of behavior, but also has cognitive functions. Mirror neurons have provided a new perspective on how sensory information regarding others’ actions and gestures is coupled with the internal cortical motor representation of them. This coupling allows an individual to enrich his interpretation of the social world through the activation of his own motor representations. Such mechanisms have been highly preserved in evolution as they (...) are present in humans, apes and monkeys. Recent neuroanatomical data showed that there are two different connectivity patterns in mirror neuron networks in the macaque: one is concerned with sensorimotor transformation in relation to reaching and hand grasping within the traditional parietal-premotor circuits; the second one is linked to the mouth/face motor control and the new data show that it is connected with limbic structures. The mouth mirror sector seems to be wired not only for ingestive behaviors but also for orofacial communicative gestures and vocalizations. Notably, the hand and mouth mirror networks partially overlap, suggesting the importance of hand-mouth synergies not only for sensorimotor transformation, but also for communicative purposes in order to better convey and control social signals. (shrink)

This paper reports about our investigation on action understanding in the brain. We review recent results of the neurophysiology of the mirror system in the monkey. Based on these observations we propose a model of this brain system which is responsible for action recognition. The link between object affordances and action understanding is considered. To support our hypothesis we describe two experiments where some aspects of the model have been implemented. In the first experiment an action recognition system is (...) trained by using data recorded from human movements. In the second experiment, the model is partially implemented on a humanoid robot which learns to mimic simple actions performed by a human subject on different objects. These experiments show that motor information can have a significant role in action interpretation and that a mirror-like representation can be developed autonomously as a result of the interaction between an individual and the environment. (shrink)

The pressure control for a liquid nature gas ship is vital for the cargo handling system which is a nonlinear, unstable, and controllable complex system accompanied by the dynamics of time delay. To improve the control effect, this article proposed a robust controller based on closed-loop gain shaping algorithm by mirror-mapping approach. In addition, the complete mechanism models for the system are established to predict the changes of temperature, pressure, and liquid inventory in the cargo tank. The heat exchanges (...) and evaporation of liquid are also considered. By collecting the data from the LNG ship “Dapeng,” the system models are validated. At the same time, the comparative experiment is introduced to verify the reliability and effectiveness. The scheme has been compared with the 2-DOF structure control law of modified Smith predictor. The comparative experimental results show that the scheme proposed in this note has a strong disturbance rejection ability and steady-state performance. The controller designed in this note has advantages of simplified construction method, satisfactory control effect and robustness. (shrink)

Indian schools -- Introduction to Tibetan Buddhism -- The Nyingma tradition -- The Kadam tradition -- The Kagyü tradition -- The Shijé tradition -- The Sakya tradition -- The Jonang and minor traditions -- The Geluk tradition 1: Tsongkhapa -- The Geluk tradition 2: Tsongkhapa's successors -- The Geluk tradition 3: the distinctiveness of Geluk -- The Bon tradition -- Chinese traditions 1: non-Buddhist -- Chinese traditions 2: Buddhist -- Central Asian traditions.

In this paper, I critically examine Stephen Turner's critique of practice theory in light of recent neurophysiological discoveries regarding the “mirror neuron system” in the pre-frontal mo-tor cortex of humans and other primates. I argue that two of Turner's strongest objections against the sociological version of the practice-theoretical account, the problem of transmission and the problem of sameness, are substantially undermined when examined from the perspective of re-cently systematized accounts of embodied learning and intersubjective action understanding in-spired by these (...) developments. In addition, I show that the practice-theoretical framework out-lined by Pierre Bourdieu in the Logic of Practice and other works is, in contrast to Turner's por-trayal of a confused hodgepodge of logical errors and empirical impossibilities, largely consistent with the latest neurophysiological evidence and as such fundamentally foreshadowed more recent understandings of the neurocognitive foundations of the perception, understanding and structure of the motor schemes productive of action in the world. Also in line with these newer neurosci-entific developments, the practice-theoretical focus on the body as the central matrix generative of tacit understandings and analogical operations responsible for “higher order” systems of classi-fication emerges as the key to solving some of the thorniest problems in the theory of action: eliminating to need to resort to unwarranted “collective object” explanations for the origins of shared presuppositional frameworks. (shrink)

1. Properties of mirror neurons in monkeys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (...) . . . . 000 1.1. Action types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 000 1.2. Context effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 000 2. Is there a human ‘mirror neuron system’? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 000 2.1. Monkeys versus humans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 000 2.2. Action understanding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 000 3. The development of mirroring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 000 3.1. Imitation in newborns? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 000 3.2. Effects of experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 000 3.3. Effects of sensorimotor experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. (shrink)

In this paper, I critically assess the thesis that the discovery of mirror neuron systems provides empirical support for the simulation theory of social cognition. This thesis can be analyzed into two claims: that MNSs are involved in understanding others’ intentions or emotions; and that the way in which they do so supports a simulationist viewpoint. I will be giving qualified support to both claims. Starting with, I will present theoretical and empirical points in support of the view (...) that MNSs play a substantial role and are perhaps neces¬sary although not sufficient for understanding at least some intentions or emo¬tions. Turning to, I will argue that the work on MNSs best supports a fairly weak version of ST, according to which social cognition involves simulation simply because conceptual thought in gen¬eral has a simulationist component. In elucidating this idea, I appeal to Law¬rence Barsalou’s embodied theory of concepts. Crucially, the term “simula¬tion” here refers not to simulations of a target agent’s experience, nor even spe¬cifically to one’s own experience in a similar counterfactual situation, but to simulations of experience in general - activating sensory, motor, proprioceptive, affective, and introspective representations that match representations one would have when perceiving, carrying out actions, experiencing emotions, etc. I then sketch an expanded simulationist framework for understanding the contribution of MNSs to social cognition. The ap¬peal to empirical work on MNSs in support of ST is therefore a two-edged sword; making this appeal persuasive requires us to modify our understanding of simulation to make it line up with the empirical work. (shrink)

This commentary validates the fundamental evolutionary interconnection between the emergence of imitation and the mirror system. We present a novel computational framework for studying the evolutionary origins of imitative behavior and examining the emerging underlying mechanisms. Evolutionary adaptive agents that evolved in this framework demonstrate the emergence of neural “mirror” mechanisms analogous to those found in biological systems.

The discovery of the mirror neuron system, which occurred 25 years ago, was considered by some authors as a definitive proof of the superiority of one philosophical theory (the Simulation Theory) over another (the Theory of Theory). However, the claim to have found a definitive answer to the philosophical problem of understanding other minds from neuroscientific data is far from acceptable. In this work I will show that there is a multiplicity of possible interpretations regarding the role of (...) class='Hi'>mirror neurons, and that one of the most plausible seems consistent with the second-person perspective (Pérez and Gomila 2021). The conclusion I seek to draw from this case study is that there are no direct paths from neuroscience to the solution of (at least some) philosophical problems. (shrink)

This paper examines the claim that mirror neuron activity is the mechanism by which we come to know about the action-related intentions of others (e.g. Gallese et al 1996, Rizzolatti et al 2009), i.e. that they are a mechanism for ‘mindreading’. I agree with recent authors (e.g. Hickok 2008, Jacob 2008) who reject this view but nevertheless I argue that mirror neurons may still have a role to play in the ways in which we understand one another (social (...) cognition). If we adopt a certain kind of pluralism about social cognition then the mirror neuron system could play a role in social cognition even if it provides no access to the minds of others at all. I argue for this view and consider what the approach might entail for the ontology of the mirror neuron system. (shrink)

The notion that manual gestures played an important role in the evolution of human language was strengthened by the discovery of mirror neurons in monkey area F5, the proposed homologue of human Broca's area. This idea is central to the thesis developed by Arbib, and lending further support to a link between motor resonance mechanisms and language/communication development is the case of autism and congenital blindness. We provide an account of how these conditions may relate to the aforementioned theory.

What is the connection between mirror processes and mindreading? The paper begins with definitions of mindreading and of mirroring processes. It then advances four theses: (T1) mirroring processes in themselves do not constitute mindreading; (T2) some types of mindreading (“low-level” mindreading) are based on mirroring processes; (T3) not all types of mindreading are based on mirroring (“high-level” mindreading); and (T4) simulation-based mindreading includes but is broader than mirroring-based mindreading. Evidence for the causal role of mirroring in mindreading is drawn (...) from intention attribution, emotion attribution, and pain attribution. Arguments for the limits of mirroring-based mindreading are drawn from neuroanatomy, from the lesser liability to error of mirror-based mindreading, from the role of imagination in some types of mindreading, and from the restricted range of mental states involved in mirroring. “High-level” simulational mindreading is based on enactment imagination, perspective shifts, or self-projection, which are found in activities like prospection and memory as well as theory of mind. The role of cortical midline structures in executing these activities is examined. (shrink)

Cook et al. argue that mirror neurons originate from associative learning processes, without evolutionary influence from social-cognitive mechanisms. We disagree with this claim and present arguments based upon cross-species comparisons, EEG findings, and developmental neuroscience that the evolution of mirror neurons is most likely driven simultaneously and interactively by evolutionarily adaptive psychological mechanisms and lower-level biological mechanisms that support them.

The discovery of mirror neurons has been hailed as one of the most exciting developments in neuroscience in the past few decades. These neurons discharge in response to the observation of others’ actions. But how are we to understand the function of these neurons? In this paper I defend the idea that mirror neurons are best conceived as components of a sensory system that has the function to perceive action. In short, mirror neurons are part of a (...) hitherto unrecognized “sixth sense”. In this spirit, research should move toward developing a psychophysics of mirror neurons. (shrink)

Various deficits in the cognitive functioning of people with autism have been documented in recent years but these provide only partial explanations for the condition. We focus instead on an imitative disturbance involving difficulties both in copying actions and in inhibiting more stereotyped mimicking, such as echolalia. A candidate for the neural basis of this disturbance may be found in a recently discovered class of neurons in frontal cortex, 'mirror neurons' (MNs). These neurons show activity in relation both to (...) specific actions performed by self and matching actions performed by others, providing a potential bridge between minds. MN systems exist in primates without imitative and ‘theory of mind’ abilities and we suggest that in order for them to have become utilized to perform social cognitive functions, sophisticated cortical neuronal systems have evolved in which MNs function as key elements. Early developmental failures of MN systems are likely to result in a consequent cascade of developmental impairments characterised by the clinical syndrome of autism. (shrink)

Mirror neuron activation (MNA) has been applied to number of business ethics contexts including marketing, charitable giving, organizational connectedness, and leadership. Unfortunately, the business literature has often ignored research in philosophy and psychology which can provide insight into the application of mirror neurons to business contexts and other disciplines. I will argue that the use of mirror neurons to support business decisions cannot be established solely on the existence of neural activation as it requires higher level cognitive (...) functions that go beyond biological reductionism. But research into MNA does support their use in basic motor action understanding which is below the level of mental and psychological attributions. The corollary supports a dual-process model. On the one hand, mirror neurons are an automatic and unconscious process by which we understand human movement and, on the other hand, there is a cognitive system by which we understand action in terms of situational specifics and mental states. (shrink)

Considering the properties of mirror neurons (MNs) in terms of development and phylogeny, we offer a novel, unifying, and testable account of their evolution according to the available data and try to unify apparently discordant research, including the plasticity of MNs during development, their adaptive value and their phylogenetic relationships and continuity. We hypothesize that the MN system reflects a set of interrelated traits, each with an independent natural history due to unique selective pressures, and propose that there are (...) at least three evolutionarily significant trends that gave raise to three subtypes: hand visuomotor, mouth visuomotor, and audio–vocal. Specifically, we put forward a mosaic evolution hypothesis, which posits that different types of MNs may have evolved at different rates within and among species. This evolutionary hypothesis represents an alternative to both adaptationist and associative models. Finally, the review offers a strong heuristic potential in predicting the circumstances under which specific variations and properties of MNs are expected. Such predictive value is critical to test new hypotheses about MN activity and its plastic changes, depending on the species, the neuroanatomical substrates, and the ecological niche. (shrink)