Philosophers often consider what it is that makes us human. For biologists considering the same, the answer is often framed in the context of what are the key differences between humans and other animals.
Numerous such differences have been suggested, but over recent decades, there has been a consistent shrinking of that list. Thus, humans are no longer thought of as being unique in the ability to construct and use tools (with these skills now demonstrated in both primate and non-primate species [McGrew 1992]). Other species have a sense of self (as shown with the famed "mirror tests" [Gallup 1970]), as well as a "Theory of Mind" that encompasses the recognition that other individuals have different information than oneself (Tomasello and Call 1997). Other species are now known to communicate symbolically (e.g., vervet monkeys have vocalizations where the relationship between signal and meaning is arbitrary, and where some vocalizations serve as synonyms). A strong argument can be made for the idea that other species can be so grieved as to fall into the affective state that we term depression. And we can no longer claim to be the only species that kills its own, or that does so in organized groups (Goodall 1986).
One vestige of human uniqueness still often cited by anthropologists is culture. However, this notion has been challenged in recent years with numerous demonstrations of "culture" in other species, particularly primates. In this review, I will first consider what the term means to animal behaviorists, and theories about how cultural transmission can occur in other species. I will then review some of the most striking examples of non-human culture. Most of the examples to be discussed are narrow in focus, concerning a single feature of tool use, food acquisition or consumption, or communication. I will then expand the focus, considering cases of non-human "social culture." By this term, I mean where a particular style of sociality permeates an array of behaviors, with this assemblage of traits fulfilling the criteria for culture. I will examine in some detail a recent study presenting the most detailed case of transmission of a social culture in a non-human species, one involving a group of primates with a multi-generational culture of low rates of aggression and high rates of affiliative behaviors (such as social grooming, play or sitting in contact). Finally, I will tentatively suggest [End Page 217] that this "peaceable" non-human primate culture may be relevant to the human condition.
As a simplification, I will use "animal behavior" to refer to more specialized terms (e.g., the study of animals in natural settings [ethology], or the study of only certain taxonomic classes of animals [e.g., primatology, ornithology]). Throughout, I will use the term "animal" to mean "non-human animal species."
What does "culture" mean to an animal behaviorist?
Early studies concerning animal "culture" often used the less provocative term "social traditions" (often at the behest of reviewers). At present, while there is still frequent use of the term "tradition," "culture" has become commonplace among animal behaviorists (McGrew 1998, de Waal 2001, Whiten 2005).
Broadly, the term is used in a way that is derivative of definitions of human culture (Kroeber and Kluckhohn 1966, Cavalli-Sforza 2000, de Waal 2001), and concerns both behavior and the material manifestations of behavior. Amid the various definitions offered by animal behaviorists, all require that the behavior occur in only a subset of a species. This can include, "two or more individuals in a social unit," in populations but not an entire species, or if in an entire species, that it show regional variability (McGrew 1992, Fragaszy and Perry 2003, Whiten 2005). Moreover, such variability cannot arise from genetic factors. Thus, a distinctive behavior...