Human cooperation is highly unusual. We live in large groups composed mostly of non-relatives. Evolutionists have proposed a number of explanations for this pattern, including cultural group selection and extensions of more general processes such as reciprocity, kin selection, and multi-level selection acting on genes. Evolutionary processes are consilient; they affect several different empirical domains, such as patterns of behavior and the proximal drivers of that behavior. In this target article, we sketch the evidence from five domains that bear on the explanatory adequacy of cultural group selection and competing hypotheses to explain human cooperation. Does cultural transmission constitute an inheritance system that can evolve in a Darwinian fashion? Are the norms that underpin institutions among the cultural traits so transmitted? Do we observe sufficient variation at the level of groups of considerable size for group selection to be a plausible process? Do human groups compete, and do success and failure in competition depend upon cultural variation? Do we observe adaptations for cooperation in humans that most plausibly arose by cultural group selection? If the answer to one of these questions is "no," then we must look to other hypotheses. We present evidence, including quantitative evidence, that the answer to all of the questions is "yes" and argue that we must take the cultural group selection hypothesis seriously. If culturally transmitted systems of rules (institutions) that limit individual deviance organize cooperation in human societies, then it is not clear that any extant alternative to cultural group selection can be a complete explanation.Keywords: competition; culture; evolution; group selection; heritable variation; institutions; norms BEHAVIORAL AND BRAIN SCIENCES (2016) KARL FROST is a Ph.D. candidate in Ecology at the University of California, Davis. He researches the cultural evolution of prosociality via religion and ritual practices, using behavioral experiments, gene-culture coevolution models, and field research in Canada looking at environmental activism in the face of the tar sands oil industry and an antagonistic government. He also directs the Body Research Physical Theater and is interested in cross-cultural exchange of theater practice as theater anthropology and arts-science fusion.

The main objective of our target article was to sketch the empirical case for the importance of selection at the level of groups on cultural variation. Such variation is massive in humans, but modest or absent in other species. Group selection processes acting on this variation is a framework for developing explanations of the unusual level of cooperation between non-relatives found in our species. Our case for cultural group selection (CGS) followed Darwin's classic syllogism regarding natural selection: If variation exists at the level of groups, if this variation is heritable, and if it plays a role in the success or failure of competing groups, then selection will operate at the level of groups. We outlined the relevant domains where such evidence can be sought and characterized the main conclusions of work in those domains. Most commentators agree that CGS plays some role in human evolution, although some were considerably more skeptical. Some contributed additional empirical cases. Some raised issues of the scope of CGS explanations versus competing ones.

Kelp forests are in decline across much of their range due to place‐specific combinations of local and global stressors. Declines in kelp abundance can lead to cascading losses of biodiversity and productivity with far‐reaching ecological and socioeconomic consequences. The Salish Sea is a hotspot of kelp diversity where many species of kelp provide critical habitat and food for commercially, ecologically, and culturally important fish and invertebrate species. However, like other regions, kelp forests in much of the Salish Sea are in rapid decline. Data gaps and limited long‐term monitoring have hampered attempts to identify and manage for specific drivers of decline, despite the documented urgency to protect these important habitats. To address these knowledge gaps, we gathered a focus group of experts on kelp in the Salish Sea to identify perceived direct and indirect stressors facing kelp forests. We then conducted a comprehensive literature review of peer‐reviewed studies from the Salish Sea and temperate coastal ecosystems worldwide to assess the level of support for the pathways identified by the experts, and we identified knowledge gaps to prioritize future research. Our results revealed major research gaps within the Salish Sea and highlighted the potential to use expert knowledge for making informed decisions in the region. We found high support for the pathways in the global literature, with variable consensus on the relationship between stressors and responses across studies, confirming the influence of local ecological, oceanographic, and anthropogenic contexts and threshold effects on stressor–response relationships. Finally, we prioritized areas for future research in the Salish Sea. This study demonstrates the value expert opinion has to inform management decisions. These methods are readily adaptable to other ecosystem management contexts, and the results of this case study can be immediately applied to kelp management.

Experimental economic games are an increasingly common component of the anthropological tool kit. Yet their external validity continues to be a point of debate and active empirical investigation within economics and anthropology. I review and reorganize central concepts within the experimental economic game literature on external validity and find that-consistent with anthropological assumptions of cultural variability-game results are not reliably generalizable across different participants or contexts. However, whether or not game behavior parallels real-world behavior within the same participants or contexts remains an open question. Methodological diversity is a strength of anthropology as a discipline, and therefore anthropologists are well poised to design more effective tests of parallelism in the future. In the meantime, anthropologists borrowing experimental methods from economics should treat the relationship between behavior inside and outside of games as an open empirical question. They should also carefully consider whether the method is consistent with their theoretical assumptions and research goals. [experimental economic games, external validity, generalizability, parallelism, anthropological methods] RESUMEN Juegos económicos experimentales son un componente cada vez más común del equipo de herramientas antropológicas. Sin embargo, su validez externa continúa siendo un punto de debate e investigación empírica activa dentro de la economía y la antropología. Reviso y reorganizo conceptos centrales dentro de la literatura de juegos económicos experimentales sobre la validez externa y encuentro que-consistente con asunciones antropológicas de variabilidad cultural-los resultados de los juegos no son generalizables de forma confiable a través de diferentes participantes o contextos. Sin embargo, si el comportamiento del juego paralela o no el comportamiento del mundo real dentro de los mismos participantes o contextos permanece como una pregunta abierta. Diversidad metodológica es una fortaleza de la antropología como una disciplina, por lo tanto, antropólogos están bien posicionados para diseñar pruebas más efectivas de paralelismo en el futuro. Entre tanto, antropólogos prestando métodos experimentales de la economía podrían tratar la relación entre el comportamiento dentro y fuera de los juegos como una pregunta empírica abierta. Deberían también considerar cuidadosamente si el método es consistente con sus asunciones teóricas y metas de investigación. [juegos económicos experimentales, validez externa, capacidad de ser generalizable, paralelismo, métodos antropológicos]