Reuse is well established in molecular evolution; some analogies from this better understood field may help suggest specific aspects of reuse of neural circuits.

Jones recognizes the existence of “primitives of conceptual structures,” out of which “local representations of kinship are constructed.” NSM semantics has identified these primitives through a cross-linguistic search for lexical universals (“NSM” stands for Natural Semantic Metalanguage and also for the corresponding linguistic theory). These empirical universals provide, I argue, a better bridge between cognitive anthropology and evolutionary psychology than the abstract constructs of OT, with dubious claim to conceptual reality.

Catchy acronyms such as “WEIRD population” are good mnemonics. However, they carry the danger of distracting us from deeper issues: how to sample populations, the validity of measuring instruments, the levels of processing involved. These need to be considered when assessing claims of universality regarding how the mind works “in general” – a dominant and highly rewarded drive in the behavioral and brain sciences.

The target article proposes a theory uniting the anthropological study of kin terminology with recent developments in linguistics and cognitive science. The response to comments reaches two broad conclusions. First, the theory may be relevant to several current areas of research, including (a) the nature and scope of the regular, “grammatical” side of language, (b) the organization of different domains of conceptual structure, including parallels across domains, their taxonomic distribution and implications for evolution, and (c) the influence of conceptual structure on social structure. Second, the theory compares favorably with alternatives, including (a) the theory that kin terminology is not really that complicated, (b) the theory that kin terms mirror social categories, (c) componential analysis, and (d) kinship algebra. If further research in anthropology, linguistics, and other fields supports the theory, and confirms the psychological reality of proposed mechanisms, then kinship may emerge as a model system for the study of important issues in cognition and social organization.

Anderson claims that the hypothesis of massive neural reuse is inconsistent with massive mental modularity. But much depends upon how each thesis is understood. We suggest that the thesis of massive modularity presented in Carruthers (2006) is consistent with the forms of neural reuse that are actually supported by the data cited, while being inconsistent with a stronger version of reuse that Anderson seems to support.

Differentiation of the forms and functions of different smiles is needed, but they should be based on the empirical data on distinctions that senders and receivers make and on the physical cues that are employed. Such data would allow for a test of whether smiles can be differentiated using perceptual cues alone or whether mimicry or simulation are necessary.

Eye contact plays a critical role in many aspects of face processing, including the processing of smiles. We propose that this is achieved by a subcortical route, which is activated by eye contact and modulates the cortical areas involve in social cognition, including the processing of facial expression. This mechanism could be impaired in individuals with autism spectrum disorders.

Neural reuse demonstrates preadaptation. In accord with Rozin (1976), the process is an increase in accessibility of an originally dedicated module. Access is a dimension that can vary from sharing by two systems to availability to all systems (conscious access). An alternate manifestation is to reproduce the genetic blueprint of a program. The major challenge is how to get a preadaptation into a “position” so that it can be selected for a new function.

Although North American undergraduates represent about 0.2% of humanity, and a very unrepresentative subset, they actually provide an advance look at what humanity is becoming. In the face of globalization, this is all the more reason to study the wonderful variants of the human condition before they become homogenized.

The objection, rightfully noted but then dismissed by Henrich et al., that the observed variation across populations “may be due to various methodological artifacts that arise from translating experiments across contexts” is a theoretically profound and potentially constructive criticism. It parallels Donald Campbell's concern that many cultural differences reported by psychologists “come from failures of communication misreported as differences.” Ironically, Campbell's doubt is a good foundation for investigations in cultural psychology.

Gender differences in face-based emotion recognition, notably differential use of mimicry, may compromise the extent to which the Simulation of Smiles (SIMS) model can be generalized to populations besides the adult females on which it has been tested. Much work indicates sex differences in face-based emotion recognition, including smile recognition.

We propose an analogy between optical holography and neural behavior as a hypothesis about the physical mechanisms of neural reuse. Specifically, parameters in optical holography (frequency, amplitude, and phase of the reference beam) may provide useful analogues for understanding the role of different parameters in determining the behavior of neurons (e.g., frequency, amplitude, and phase of spiking behavior).

In distinguishing itself from other distributed approaches to cognition, Anderson's theory of neural reuse is susceptible to some of the same criticisms that have been leveled at modular approaches. Specifically, neural reuse theories state that: (1) the “working” of a given brain circuit is fixed, rather than shaped by its input, and (2) that high-level cognitive behaviors can be cleanly mapped onto a specific set of brain circuits in a non-contextualized manner.

The parent-infant dyad, characterized by contingent social interactions that develop over the first three months postpartum, may depend heavily on parental brain responses to the infant, including the capacity to smile. A range of brain regions may subserve this social key function in parents and contribute to similar capacities in normal infants, capacities that may go awry in circumstances of reduced care.

From Plato to the present, philosophers have relied on intuitive judgments as evidence for or against philosophical theories. Most philosophers are WEIRD, highly educated, and male. The literature reviewed in the target article suggests that such people might have intuitions that differ from those of people in other groups. There is a growing body of evidence suggesting that they do.

In our response to the 28 (largely positive) commentaries from an esteemed collection of researchers, we (1) consolidate additional evidence, extensions, and amplifications offered by our commentators; (2) emphasize the value of integrating experimental and ethnographic methods, and show how researchers using behavioral games have done precisely this; (3) present our concerns with arguments from several commentators that separate variable “content” from “computations” or “basic processes”; (4) address concerns that the patterns we highlight marking WEIRD people as psychological outliers arise from aspects of the researchers and the research process; (5) respond to the claim that as members of the same species, humans must have the same invariant psychological processes; (6) address criticisms of our telescoping contrasts; and (7) return to the question of explaining why WEIRD people are psychologically unusual. We believe a broad-based behavioral science of human nature needs to integrate a variety of methods and apply them to diverse populations, well beyond the WEIRD samples it has largely relied upon.

Embodied simulation and the epistemic motivation to search for the “meaning” of other people's behaviors are not necessary for specific and functional responding to, and hence processing of, human facial expressions. Rather, facial expression processing can be achieved through lower-cognitive, heuristical perceptual processing and expression of prototypical morphological musculature movement patterns that communicate discrete trustworthiness and capacity cues to conspecifics.

I agree with Anderson's approach to reuse theories. My main concern is twofold. Anderson assumes certain nomological regularities in reuse phenomena that are simply conjectures supported by thin evidence. On the other hand, a biological theory of reuse is insufficient, in and of itself, to address the evaluation of particular models of cognition, such as concept empiricism or conceptual metaphor.