There are many methodological considerations – some intricately associated with the use of WEIRD samples – that adversely affect external validity as much as, or even more than, unrepresentative sampling does. Among suspect applications, especially worrisome is the incorporation of WEIRD-based findings regarding moral reasoning and retribution into normative expectations, such as might be held by international criminal tribunals in “cognitively distant” war-torn areas.

Coall & Hertwig (C&H) demonstrate the importance of grandparents to children, even in low fertility societies. We suggest policy-makers interested in reproductive timing in such contexts should be alerted to the practical applications of this cooperative breeding framework. The presence or absence of a supportive kin network could help explain why some women begin their reproductive careers “too early” or “too late.”

Anderson's meta-analysis of fMRI data is subject to a potential confound. Areas identified as active may make no functional contribution to the task being studied, or may indicate regions involved in the coordination of functional networks rather than information processing per se. I suggest a way in which fMRI adaptation studies might provide a useful test between these alternatives.

The choice of emphasis in kinship studies has often resulted in incompatible theoretical models of kinship that are mutually undermining and contradictory. Jones' attempts to reconcile disparate approaches to kinship using OT is useful, however; seeing kinship as a specialized system for representing genealogy may be unwarranted in the light of recent advances in mathematical approaches to kinship terminologies.

A complete model of smile interpretation needs to incorporate its social context. We argue that embodied simulation is an unlikely route for understanding dominance smiles, which typically occur in the context of power. We support this argument by discussing the lack of eye contact with dominant faces and the facial and postural complementarity, rather than mimicry, that pervades hierarchical relationships.

While the idea of applying Optimality Theory to kinship has potential, this commentary draws attention to problems with the constraints proposed. Particularly, Distinguish Matrikin appears to recapitulate an error of linking matrilineal descent to Iroquois kinship too closely and more generally mixing descent with true kinship parameters.

The SIMS model claims that it is by means of an embodied simulation that we determine the meaning of an observed smile. This suggests that crucial interpretative work is done in the mapping that takes us from a perceived smile to the activation of one's own facial musculature. How is this mapping achieved? Might it depend upon a prior interpretation arrived at on the basis of perceptual and contextual information?

In discussing the effects of grandparents on child survival in natural fertility populations, Coall & Hertwig (C&H) rely extensively on the review by Sear and Mace (2008). We conducted a more detailed summary of the same literature and found that the evidence in favor of beneficial associations between grandparenting and child survival is generally weak or absent. The present state of the data on human alloparenting supports a more restricted use of the term “cooperative breeding.” Human stem family situations with celibate helpers-at-the-nest can be described as cooperatively breeding, but the term is a poor fit to many human family systems.

This commentary suggests how the target article raises new implications for brain injury therapies, which may have been anticipated by the neurologist Kurt Goldstein, though he worked in and earlier era of fervent localization of brain function.

This commentary will extend the territory claimed in the target article by identifying several other areas in the social sciences where findings from the WEIRD population have been over-generalized. An argument is made that the root problem is the ethnocentrism of scholars, textbook authors, and social commentators, which leads them to take their own cultural values as the norm.

Jones argues that extending Seneca kin terms to second cousins requires a revised version of Optimality Theoretic grammar. I extend Seneca terms using three constraints on expression of markers in nested binary classification trees. Multiple constraint rankings on a nested set coupled with local parity checking determines how a given kin classification grammar marks structural endogamy.

We propose the SIMS model can be strengthened by detailing the dynamic interaction between sensorimotor activation and contextual conceptual information. Rapidly activated evaluations and contextual knowledge can guide and constrain embodied simulations. In addition, we stress the potential importance of extending the SIMS model to dynamic social interactions that go beyond the passive observer.

Chemistry, genetics, physics, and linguistics all present instances of reuse. I use the example of how behavioral constraints may have contributed to the emergence of phonemic reuse. Arising from specific facts about speech production, perception, and learning, such constraints suggest that combinatorial reuse is domain-specific. This implies that it would be more prudent to view instances of neural reuse not as reflecting a “fundamental organizational principle,” but as a fortuitous set of converging phenomena.

Henrich et al. convincingly caution against the overgeneralization of findings from particular human populations, but fail to apply their own compelling reasoning to our nearest living relatives, the great apes. Here we argue that rearing history is every bit as important for understanding cognition in other species as it is in humans.

Integration of different lines of research concerning grandparental investment appears to be both promising and necessary. However, it must stop short when confronted with incommensurate arguments and hypotheses, either within or between disciplines. Further, some hypotheses have less plausibility and veridicality than others. This point is illustrated with results that conflict previous conclusions from evolutionary psychology about differential grandparental investment.

Jones uses a mechanism from the linguistic theory, Optimality Theory, to generate the range of kin systems observed in human cultures and human languages. The observed distribution of kinship systems across human societies suggests that some possibilities are preferred over others, a result that would indicate Jones' model needs to be refined, especially in its treatment of markedness.

Previous studies with Westerners have found that both the mouth and eyes are crucial in identifying and interpreting smiles. We proposed that Easterners (e.g., Chinese and Japanese) evaluate the role of the mouth and eyes in smiles differently from Westerners. Individuals in collectivistic Eastern society heavily rely on information from the eyes to identify and interpret the meaning of smiles.

In this commentary, I argue that to properly assess the significance of the cross-cultural findings reviewed by Henrich et al., one needs to understand better the causes of the variation in performance in experimental tasks across cultures.

This response outlines more reasons why we need the integrative framework of grandparental investments and intergenerational transfers that we advocated in the target article. We discusses obstacles – from misconceptions to poor measures – that stand in the way of such a framework and of a better understanding of the effects of grandparenting in the developed world. We highlight new research directions that have emerged from the commentaries, and we end by discussing some of the things in our target article about which we may have been wrong.

With his massive redeployment hypothesis (MRH), Anderson claims that novel cognitive functions are likely to rely on pre-existing circuits already possessing suitable resources. Here, we put forward recent findings from studies in numerical cognition in order to show that the role of sensorimotor experience in the ontogenetical development of a new function has been largely underestimated in Anderson's proposal.