Erdelyi's version of repression – trying successfully not to think about something – is no longer recognizably Freudian. Erdelyi fails to cite directed forgetting experiments involving psychiatric patients that indicate that the motivation to forget threatening material seldom translates into an ability to do so. The early Freud of the seduction theory of hysteria did inspire the recovered memory fiasco.

Keller & Miller's (K&M's) treatment of disorders usefully avoids diagnostic minutiae; but it needs more real-world constraints. Classifying processes by their evolutionary age helps to clarify both evolution and current function. Evolutionarily old, optimised, normative processes deserve special recognition, because they can be studied in animals and computers, and because they provide the machinery through which disorder-related polymorphisms act.

Our response amplifies our case that money is best seen as both a drug and a tool. Some commentators challenge our core assumptions: In this response we, therefore, explain in more detail why we assume that money is an exceptionally strong motivator, and that a biological explanation of money motivation is required. We also provide evidence to support those assumptions. Other commentators criticise our use of the drug metaphor, particularly arguing that it is empirically empty; and in our response we seek to show how it can be submitted to test – aided by some commentaries which suggest such tests. In addition, we explain, with evidence, why we do not think that the notion of money as a generalised conditioned reinforcer provides a satisfactory alternative to the tool/drug account. The largest group of commentaries suggests alternative instincts on which the drug-like effects of money might be based, other than the reciprocation and play instincts we propose; in our response, we explain why we still prefer our original proposals, but we accept that alternative or additional instincts may indeed underlie money motivation. A final group of commentaries carries the argument further, suggesting extensions to the tool/drug model, in ways with which we are broadly in sympathy. The purpose of the tool and drug metaphors is to encourage reflection on the biological origins of money motivation, and to that extent at least we believe that they have succeeded.

Of three types of evidence available to evolution theoristscomparative, continuity, and computationalthe first is largely productive rather than predictive. Although comparison between extant species or languages is possible and can be suggestive of evolutionary processes, leading to theory development, comparison with extinct species and languages seems necessary for validation. Continuity and computational evidence provide the best opportunities for supporting predictions.

The uniqueness of human cognition and language has long been linked to systematic changes in developmental timing. Selection for postnatal skeletal ossification resulted in progressive prolongation of universal patterns of primate growth, lengthening infancy, childhood, and adolescence. Language emerged as communication increased in complexity within and between communities rather than from selection for some unique features of childhood or adolescence, or both.

Erdelyi argues persuasively for his unified theory of repression. Beyond this, what can studying repression bring to our understanding of other aspects of emotional function? Here we consider ways in which work on repression might inform the study of, on one hand, emotional memory, and on the other, the emotional numbing seen in patients with chronic persistent depersonalization symptoms.

First kudos, followed by some friendly badinage, and then renewed appreciation and a look ahead. This commentary is meant to clarify main arguments, redress incorrect attributions, and strengthen an excellent contribution that draws further attention to the importance of evolutionary epidemiology. Keller & Miller (K&M), despite significant errors, have done well to further systematize the evolutionary epidemiology of psychopathology.

The social function of language, as exemplified by tonic communication, is certainly not restricted to our own species. An individual's cognitive mastering of its environment, moreover, is equally essential for understanding the nature of any language. In the absence of comparative data, it is premature to claim that language skills at a particular developmental stage are uniquely human.

Erdelyi's account of thought suppression, which he equates with the Freudian construct of repression, is that it is mostly successful, and that it undermines memory for the suppressed material. Erdelyi has neglected to consider evidence from two decades of research on suppression which renders both these claims invalid. Contrary to Erdelyi's thesis, suppression often enhances the accessibility of unwanted material.

This response (a) integrates non-equilibrium evolutionary genetic models, such as coevolutionary arms-races and recent selective sweeps, into a framework for understanding common, harmful, heritable mental disorders; (b) discusses the forms of ancestral neutrality or balancing selection that may explain some portion of mental disorder risk; and (c) emphasizes that normally functioning psychological adaptations work against a backdrop of mutational and environmental noise.

By shifting the focus of analysis from forgetting and remembering to interpreting and making-meaning, Erdelyi allows theoretical consideration of repression to move beyond the heuristic assumption that personal memory is necessarily private memory. In this commentary, repression is considered to be a collective process in which memories are shaped by the need for coherence between individual and social narratives.

The target article by Locke & Bogin (L&B) focuses on the evolution of language as a communicative tool. They neglect, however, that from infancy onwards humans have the ability to go beyond successful behaviour and to reflect upon language (and other domains of knowledge) as a problem space in its own right. This ability is not found in other species and may well be what makes humans unique.

Erdelyi grants “repression” emotional and cognitive qualities that can modulate consciousness and probably overlap with what is typically attributed to “attention.” Such a broad appellation of repression explains virtually all behavior and lacks specificity. Repression and attention elucidate behavior in different clinical, cognitive, and cultural contexts. Refining these influences, we identify a few lacunae in Erdelyi's account.

Locke & Bogin (L&B) propose that humans are unique in possessing stages of childhood and adolescence. Arguments to the contrary include evidence for a similar and adaptive juvenile period in simians of slow growth, intense play and learning, and provisioning with solid food by adults. Likewise, simians as well as humans undergo a compensatory growth spurt during puberty.

Although Freud's merits may be readily acknowledged in the year of his 150th birthday, recent findings on repression-related phenomena cannot be accommodated by his classic conception, on which Erdelyi's theory is built. This point is illustrated by discussing the role of inhibitory processes. The unified theory of repression should be elaborated to generate falsifiable predictions on the reported phenomena.

The stormy development of vocal production during the first postnatal weeks is generally underestimated. Our longitudinal studies revealed an amazingly fast unfolding and combinatorial complexification of pre-speech melodies. We argue that relying on melody could provide for the immature brain a kind of filter to extract life-relevant information from the complex speech stream.

The finding of the same language deficit in half the members of the KE family is taken as suggesting that a specific allele (FOXP2) is normally involved in the development of language. Recent studies, however, question the exclusivity of FOXP2, and it is argued that the finding of a gene that disrupts language should not be taken as strong evidence for the existence of genes that underlie it.

From the perspective of modern dream research, Freud's hypotheses regarding repression and dreaming are difficult to evaluate. Several studies indicate that it is possible to study these topics empirically, but it needs a lot more empirical evidence, at least in the area of dream research, before arriving at a unified theory of repression.

Normal adults recall poorly social feedback that refers to them, is negative, and pertains to core self-aspects. This phenomenon, dubbed the mnemic neglect effect, is equivalent to inhibitory repression. It is instigated under conditions of high self-threat, it implicates not-thinking during encoding, and it involves memories that are recoverable with such techniques as recognition accuracy.

Language, like other human traits, could only have evolved during one or more stages of development. We enlist the theoretical framework of human life history to account for certain aspects of linguistic evolution, with special reference to initial phases in the process. It is hypothesized that selection operated at several developmental stages, the earlier ones producing new behaviors that were reinforced by additional, and possibly more powerful, forms of selection during later stages, especially adolescence and early adulthood. Peer commentaries have provided opportunities to explain human life history more comprehensively, and to add details to our account of spoken language. We made no attempt to explain syntax in the target article, but we propose here that selection for vocal plumage may have increased our species capacity for utterance complexity, a development that would have benefited all levels of language.