The human species is an outlier in the natural world. Two million years ago our ancestors were a slightly odd apes. Now we occupy the largest ecological and geographical range of any species, have larger biomass, and process more energy. Usually, this transformation is explained in terms of cognitive ability—people are just smarter than all the rest. In this paper I argue that culture, our ability to learn from each other, and cooperation, our ability to make common cause with large groups of unrelated individuals are the real roots of human uniqueness, and sketch an evolutionary account of how these crucial abilities co-evolved with each other and with other features of our life histories.

The comparative and evolutionary analysis of social learning and all manner of cultural processes has become a flourishing field. Applying the ‘comparative method’ to such phenomena allows us to exploit the good fortunate we have in being able to study them in satisfying detail in our living primate relatives, using the results to reconstruct the cultural cognition of the ancestral forms we share with these species. Here I offer an overview of principal discoveries in recent years, organized through a developing scheme that targets three main dimensions of culture: the patterning of culturally transmitted traditions in time and space; the underlying social learning processes; and the particular behavioral and psychological contents of cultures. I focus on a comparison between humans, particularly children, and our closest primate relative the chimpanzee, for which we now have much the richest database of relevant observational and experimental findings. Commonalities across these sister-species can be identified in each of the three dimensions listed above and in several subcategories within them, but the comparisons also highlight the major contrasts in the nature of culture that have evolved between ourselves and closest primate relatives.

Classical ethology and behavioral ecology did not pay much attention to learning. However, studies of social learning in nature reviewed here reveal the near-ubiquity of reliance on social information for skill acquisition by developing birds and mammals. This conclusion strengthens the plausibility of the cultural intelligence hypothesis for the evolution of intelligence, which assumes that selection on social learning abilities automatically improves individual learning ability. Thus, intelligent species will generally be cultural species. Direct tests of the cultural intelligence hypothesis require good estimates of the amount and kind of social learning taking place in nature in a broad variety of species. These estimates are lacking so far. Here, we start the process of developing a functional classification of social learning, in the form of the social learning spectrum, which should help to predict the mechanisms of social learning involved. Once validated, the categories can be used to estimate the cognitive demands of social learning in the wild.

Humans exhibit extensive large-scale cooperation, of a form unprecedented in the natural world. Here I suggest that this cooperation arises in our species alone because of our uniquely potent capacities for social learning, imitation and teaching, combined with the co-evolutionary feedbacks that these capabilities have generated on the human mind. Culture took human populations down evolutionary pathways not available to non-cultural species, either by creating conditions that promoted established cooperative mechanisms, such as indirect reciprocity and mutualism, or by generating novel cooperative mechanisms not seen in other taxa, such as cultural group selection. In the process, gene-culture co-evolution seemingly generated an evolved psychology, comprising an enhanced ability and motivation to learn, teach, communicate through language, imitate and emulate, as well as predispositions to docility, social tolerance, and the sharing of goals, intentions and attention. This evolved psychology is entirely different from that observed in any other animal, or that could have evolved through conventional selection on genes alone.

In humans and other animals, the individuals’ ability to adapt efficiently and effectively to the niches they have actively contributed to construct relies heavily on an evolved psychology which has been shaped by biological, social, and cultural processes over evolutionary time. As expected, although many of the behavioral and cognitive components of this evolved psychology are widely shared across species, many others are species-unique. Although many animal species are known to acquire group-specific traditions (or cultures) via social learning, human culture is unique in terms of its contents and characteristics (observable and unobservable products, cumulative effects, norm conformity, and norm enforcement) and of its cognitive underpinnings (imitation, instructed teaching, and language). Here we provide a brief overview of some of the issues that are currently tackled in the field. We also highlight some of the strengths of a biological, comparative, non-anthropocentric and evolutionarily grounded approach to the study of culture. The main contributions of this approach to the science of culture are its emphasis (a) on the integration of information on mechanisms, function, and evolution, and on mechanistic factors located at different levels of the biological hierarchy, and (b) on the search for general principles that account for commonalities and differences between species, both in the cultural products and in the processes of innovation, dissemination, and accumulation involved that operate during developmental and evolutionary timespans.