Can the Internet reach beyond the U. S. college samples predominant in social science research? A sample of 564,502 participants completed a personality questionnaire online. We found that 19% were not from advanced economies; 20% were from non-Western societies; 35% of the Western-society sample were not from the United States; and 66% of the U. S. sample were not in the 18–22 (college) age group.

The question of why helpers help is debated in the cooperative breeding literature. Recent reevaluations of inclusive fitness theory have important implications for traditional populations in which the provisioning of young occurs in the context of intergenerational transfers. These transfers link older and younger generations in an economic relationship that both minimizes the demand for help and the cost of helping.

Niedenthal et al. recognize that cultural differences are important when interpreting facial expressions. Nonetheless, many of their core observations derive more from individualistic cultures than from collectivist cultures. We discuss two examples from the latter: (1) lower rates of mutual eye contact, and (2) the ubiquity of specific “functional smiles.” These examples suggest constraints on the assumptions and applicability of the SIMS model.

Novel functions, which emerge by reusing existing resources formerly adapted to other original usages, cannot be anticipated before the need eventually arises. Simple reuse must be accidental. However, to survive the evolutionary race, one cannot merely keep hoping for a string of good fortune. So, successful species might be gifted with “rational” and “purposeful” biological mechanisms to prepare for future reuse. Neural reuse must be extrapolated from such mechanisms.

I raise issues concerning Jones' Seneca analysis, its relationship to analyses of Dravidian-, Crow-, and Omaha-type systems. These affect the convincingness of his kinship study, and thus the wider conclusions that he wants to draw regarding human cognition and language.

Motor development – traditionally studied in WEIRD populations – falls victim to assumptions of universality similar to other domains described by Henrich et al. However, cross-cultural research illustrates the extraordinary diversity that is normal in motor skill acquisition. Indeed, motor development provides an important domain for evaluating cultural challenges to a general behavioral science.

We outline three possible shortcomings of the SIMS model and specify these by applying the model to autism. First, the SIMS model assigns a causal role to brain processes, thereby excluding individual and situational factors. Second, there is no room for subjective and high-level conceptual processes in the model. Third, disentangling the different stages in the model is very difficult.

As societies industrialize, the age profile of consumption tilts strongly toward the elderly, while elder labor supply drops. Low fertility and long life lead to population aging. For millennia, material resources have, on net, flowed downward from older to younger within populations, but now in many rich societies net flows have reversed and go upwards from young to old.

Anderson's theory is plausible and largely consistent with the data. However, it remains underspecified on several fronts, and we highlight areas for potential improvement. Reuse is described as duplicating a functional component, preserving one function and tinkering to add another function. This is a promising model, but Anderson neglects other reasonable alternatives and we highlight several. Evidence cited in support of reuse fails to uniquely support it among a broader set of multi-use theories. We suggest that a more stringent criterion for direct support of reuse may be satisfied by focusing on previous adaptive functions (original use).

Jones' article suggests that the anthropological analysis of kinship has followed a single line of development based on a single underlying conception of meaning and method. In fact, there have been two opposed lines of development. Jones' conception is positivistic. The other is pragmatic. Pragmatic theory is superior on every recognized criterion. This briefly describes the differences.

Jones's system of constraints promises interesting insights into the typology of kin term systems. Three problems arise: (1) the conflation of categories with algorithms that assign them threatens to weaken the typological predictions; (2) OT-type constraints have little psychological plausibility; (3) the conflation of kin-term systems and kinship systems may underplay the “utility function” character of real kinship in action.

To refine our understanding of grandparental investment and its consequences, we need to understand what grandparents do for their grandchildren. Knowing the landscape of grandparental investment will facilitate a better understanding of the impact of grandparental investment on grandchildren and will allow inroads to be made in bridging the different levels of analysis.

We emphasize the value of the socio-ecological approach in addressing the problem of population variances. The socio-ecological perspective studies how social and natural habitats shape human behaviors, and are in turn shaped by those behaviors. This focus on system-level factors is particularly well-suited to studying the origins of group differences in human behavior.

Comparative studies demonstrate that homologous neural structures differ in function and that neural mechanisms underlying behavior evolved independently. A neural structure does not serve a particular function so much as it executes an algorithm on its inputs though its dynamics. Neural dynamics are altered by a neuromodulation, and species-differences in neuromodulation can account for behavioral differences.

We question two conceptual assumptions made by Niedenthal et al.: the dichotomy between true and false smiles and the close tie between recognition and experience of emotion. An excessive dependence on everyday language suggests overly parsimonious accounts of a complex set of relations between smile, experience, and context.

Anderson's massive redeployment hypothesis (MRH) takes the grounding of meaning in sensorimotor behaviour to be a side effect of neural reuse. I suggest this grounding may play a much more fundamental role in accounting for the bootstrapping of higher-level cognition from sensorimotor behaviour. Thus, the question of when neural reuse delivers semantic inheritance is a pressing one for MRH.

We focus on the role that motor mimicry plays in the SIMS model when interpreting whether a facial emotional expression is appropriate to an eliciting context. Based on our research, we find general support for the SIMS model in these situations, but with some qualifications on how disruption of motor mimicry as a process relates to speed and accuracy in judgments.

Henrich et al. address how culture leads to cognitive variability and recommend that researchers be critical about the samples they investigate. However, there are other sources of variability, such as individual strategies in reasoning and the content and context on which processes operate. Because strategy and content drive variability, those factors are of primary interest, while culture is merely incidental.

We designed an experiment to test the application of optimality theory (OT) in kinship terminology studies. Specifically, we examined the OT constraints within a set of behavioral data using Chinese kin terms. The results from this behavioral approach support and extend Jones' linguistic approach by identifying underlying cognitive mechanisms that can explain and predict behavioral responses in kinship identification.

Coall & Hertwig (C&H) give an ambitious review about the broad range of grandparenting literature from the perspective of different disciplines. They aim to show, how evolutionary theory, sociology, and economics can mutually enrich each other. However, the differences between the evolutionary and the socio-economic perspective should be more clearly pointed out, because they usually deal with different research questions. Grandparents' well-being could be divided into its underlying components.