We suggest that human culture exhibits key Darwinian evolutionary properties, and argue that the structure of a science of cultural evolution should share fundamental features with the structure of the science of biological evolution. This latter claim is tested by outlining the methods and approaches employed by the principal subdisciplines of evolutionary biology and assessing whether there is an existing or potential corresponding approach to the study of cultural evolution. Existing approaches within anthropology and archaeology demonstrate a good match with the macroevolutionary methods of systematics, paleobiology, and biogeography, whereas mathematical models derived from population genetics have been successfully developed to study cultural microevolution. Much potential exists for experimental simulations and field studies of cultural microevolution, where there are opportunities to borrow further methods and hypotheses from biology. Potential also exists for the cultural equivalent of molecular genetics in “social cognitive neuroscience,” although many fundamental issues have yet to be resolved. It is argued that studying culture within a unifying evolutionary framework has the potential to integrate a number of separate disciplines within the social sciences.

Mesoudi et al. argue that the current inability to identify the means by which cultural traits are acquired does not debilitate their project to draw clear parallels between cultural and biological evolution. However, I suggest that cultural phenomena may be accounted for by biological processes, unless we can identify a cultural “genotype” that carries information from person to person independently of genes.

Vertical/compatible theoretical integration provides an alternative way of unifying sociocultural anthropology and related disciplines. It involves analyzing theoretical statements for their implicit and explicit assumptions at multiple levels of analysis and then determining whether these assumptions are compatible with consensus in the relevant disciplines (e.g., does the sociological theory include an assumption at odds with consensus psychology?). Incompatibilities indicate a need for further research. This approach is much more likely to salvage the bulk of humanities-oriented anthropology than is that of the authors.

Memes are not best understood as semantic information stored in brains, but rather, as whatever is imitated or copied in culture. Whereas other theories treat culture as an adaptation, for memetics it is a parasite turned symbiont that evolves for its own sake. Memetics is essential for understanding today's information explosion and the future evolution of culture.

The analogy between biological and cultural evolution is not perfect. Yet, as Mesoudi et al. show, many of the vaunted differences between cultural and genetic evolution (for example, an absence of discrete particles of cultural inheritance, and the blurred distinction between cultural replicators and cultural phenotypes) are, on closer inspection, either illusory or peripheral to the validity of the analogy. But what about horizontal transmission? We strongly agree with the authors that the potential for horizontal transmission of cultural traits does not invalidate an evolutionary approach to culture. We suggest, however, that it does require a different evolutionary treatment.

An effective restructuring of the social sciences around the evolutionary model requires that evolutionary theory has explanatory power with respect to the spread of cultural traits: The causal mechanisms involved should be structurally analogous to those of biological evolution. I argue that this is implausible because phenotypical consequences of cultural traits are not causally relevant to their chances of “survival.”

Mathematical models are potentially as useful for culture as for evolution, but cultural models must have different designs from genetic models. Social sciences must borrow from biology the idea of modeling, rather than the structure of models, because copying the product is fundamentally different from copying the design. Transfer of most cultural information from brains to artificial media increases the differences between cultural and biological information.

Intelligent design, though unnecessary in the study of biological evolution, is essential to the study of cultural evolution. However, the intelligent designers in question are not deities or aliens but rather humans going about their lives. The role of intentionality in cultural evolution can be elucidated through the addition of signaling theory to the framework outlined in the target article.

Mesoudi et al. overlook an illuminating parallel between cultural and biological evolution, namely, the existence in each realm of a continuum from intelligent, mindful evolution through to oblivious, mindless evolution. In addition, they underplay the independence of cultural fitness from biological fitness. The assumption that successful cultural traits enhance genetic fitness must be sidelined, as must the assumption that such traits will at least be considered worth having.

Examining homology in biological and cultural evolution is of great importance in investigations of humanity. The proposal presented in the target article retains substantial methodological weaknesses in the identification and use of “cultural traits.” However, with refined toolkits and the incorporation of recent advances in evolutionary theory, this overall endeavor can result in substantial payoffs for biological and social scientists.

Although we are enthusiastic about a Darwinian approach to culture, we argue that the overview presented in the target article does not sufficiently emphasize the crucial explanatory role that psychology plays in the study of culture. We use a number of examples to illustrate the variety of ways by which appeal to psychological factors can help explain cultural phenomena.

Mesoudi et al.'s case can be improved by expanding to compelling selectionist explanations elsewhere in the social sciences and by seeing that natural selection is an instance of general selectionist process. Obstacles include the common use of extreme idealizations and optimality evidence, the copresence of nonselectionist social processes, and the fact that selectionist explanations often presuppose other kinds of social explanations.

Advancing a general Darwinian framework to explain culture is an exciting endeavor. It requires that we face up to the challenge of identifying the specific components that are effective in replication processes in culture. This challenge includes the unsolved problem of explaining cultural inheritance, both at the level of individuals and at the level of social organizations and institutions.

Modern efforts to model cultural transmission have struggled to identify a unit of cultural transmission and particular transmission processes. Anthropologists of the early twentieth century discussed cultural traits as units of transmission equivalent to recipes (rules and ingredients) and identified integration as a signature process and effect of transmission.

Understanding cultural evolution is one of the most challenging and indispensable scientific tasks for the survival of humankind on our planet. This task demands, besides an adoption of theories and models from biological evolution, theories for culture-specific processes as well. Language evolution and language acquisition offer interesting objects of study in this respect.

Given the numerous parallels between the archaeological and paleontological records, it is not surprising to find a considerable fit between macroevolutionary approaches and methods used in biology – for example, cladistics and clade-diversity measures – and some of those that have long been used in archaeology – for example, seriation. Key, however, is recognizing that this methodological congruence is illusory in terms of how evolution has traditionally been viewed in biology and archaeology.

The study of culture from an evolutionary perspective has been slowed by resistance from some quarters of anthropology, a poor appreciation of the fidelity of cultural transmission, and misunderstandings about human intentionality.

Darwinian evolution, defined as evolution arising from selection based directly on the properties of individuals, does not account for cultural constructs providing the organizational basis of human societies. The difficulty with linking Darwinian evolution to structural properties of cultural constructs is exemplified with kinship terminologies, a cultural construct that structures and delineates the domain of kin in human societies.

Evolutionary developmental biology (“evo-devo”) may provide insights and new methods for studies of cognition and cultural evolution. For example, I propose using cultural selection and individual learning to examine constraints on cultural evolution. Modularity, the idea that traits vary independently, can facilitate evolution (increase “evolvability”), because evolution can act on one trait without disrupting another. I explore links between cognitive modularity, evolutionary modularity, and cultural evolvability.

Analogies between biological and cultural evolution may be illuminating and suggest methods to pursue in the quest for a unified science of cultural evolution. Significant progress, however, is unlikely to be made by trying to fit cultural evolution neatly into a biological evolution schema. A key element defining and differentiating cultural evolution may be the role of conscious human choices.