Brain physiology and IQ gains over time both show that various cognitive skills, such as on-the-spot problem solving and arithmetic reasoning, are functionally independent, despite being bundled up in the correlational matrix called g. We need a theory of intelligence that treats the physiology and sociology of intelligence as having integrity equal to the psychology of individual differences.

Further understanding at neuroscientific and personality levels should considerably advance our ability to deal with individuals that have strong sociopathic tendencies. An analysis of neurodynamic responses to emotional stimuli will eventually be able to detect sociopathic tendencies of the brain. Such information could be used to enhance the options available to individuals at risk without limiting their personal freedoms.

The idea of representing words with cell assemblies is very appealing. However, syntactic sequences need to be represented as well. This cannot be done by using the activity levels of assemblies. Instead, structural relations and operations between assemblies are needed to achieve serial order in syntactic word strings.

Jackendoff's scenario of the evolution of language is a major contribution towards a more rigorous theory of the origins of language, because it is theoretically constrained by a testable theory of modern language. However, the theoretical constraints from evolutionary theory are not really recognized in his work. We hope that Jackendoff's lead will be followed by intensive cooperation between linguistic theorists and evolutionary modellers.

We elaborate on the role of individual differences in the processing mechanisms outlined by the Distancing-Embracing model. The role of openness is apparent in appreciating meaning-making art that elicits interest, feeling moved, and mixed emotions. The influence of sensation seeking is likely to manifest in thrill-chasing art that draws on the arousing interplay of positive and negative emotions.

The facial expression of pain is the end product of a complex process that is, in part, emotional. The evolutionary study of facial expression must account for the social nature of human consciousness and should address the questions of why empathy exists, the adaptive importance of empathy, and whether facial expression is a mechanism of empathy and second-person consciousness.

Interpreting heritability estimates through the lens of cultural evolution presents two broad and interlinking problems for educational behavior genetics. First, the problem of interpreting high heritability of educational phenotypes as indicators of the genetic basis of traits, when these findings also reflect cultural homogeneity. Second, the problem of extrapolating from genetic research findings in education to policy and practice recommendations.

Sussman et al. describe an ecological property of the speech signal that is putatively functional in perception. An important issue, however, is whether their putative cue is an emerging feature or whether the second formant (F2) onset and the F2 vowel actually provide independent cues to perceptual categorization. Regardless of the outcome of this issue, an important goal of speech research is to understand how multiple cues are evaluated and integrated to achieve categorization.

Although compelling and insightful, the proposal by Uchiyama et al. largely neglects within-person change over time, arguably the central topic of interest within their framework. Longitudinal behavioural genetics modelling suggests that the heritability of trajectories is low, in contrast to high and increasing cross-sectional heritability across development. Better understanding of the mechanisms of trajectories remains a crucial outstanding challenge.

Food insecurity relates to fat storage, but cannot explain fat storage in excess of levels optimal for buffering – that is, obesity. However, factors related to food unpredictability in the past, including stress, disease, micronutrient content of food, and physical activity, may cue physiological processes that change intake or fat deposition even in the absence of actual food unpredictability.

Uchiyama et al. present a dual inheritance framework for conceptualizing how behavioural genetics and cultural evolution interact and affect heritability. We posit that to achieve a holistic and nuanced representation of the cultural environment and evolution against which genetic effects should be evaluated, it is imperative to consider the multiple geographic cultural layers impacting individuals and genetic heritability.

Andrews et al. subscribe to the view that distinguishing selectionist from nonselectionist hypotheses – or, distinguishing adaptations from mere spandrels or exaptations – is important to the study of psychology. I offer three reasons for thinking that this view is false; that considerations of past selective efficacy have little to contribute to inquiry in psychology.

Any instance (i.e., event, behavior, trait) belongs to infinitely many reference classes, hence there are infinitely many base rates from which to choose. People clearly do not entertain all possible reference classes, however, so something must be limiting the search space. We suggest some possible mechanisms that determine which reference class is evoked for the purpose of judgment and decision.

This commentary is a call to action for researchers to create and use genome-wide association studies (GWASs) with previously missed age groups (e.g., infancy, elderly), which will improve our ability to ask important developmental questions using genetic data to trace pathways across the lifespan.

De Neys proposes that deliberation is triggered and sustained by uncertainty. I argue that there are cases where deliberation occurs with low uncertainty – such as when problems are excessively complicated and the reasoner decides against engaging in deliberation – and that there are likely multiple factors that lead to (or undermine) deliberation. Nonetheless, De Neys is correct to surface these issues.