Cultural changes in animal societies are said to occur when animals learn new habits of living and pass them along to the next generation. In such a situation, the spread of a certain innovation results in stable conservation of a new custom that is further maintained and transmitted in a train of generations through social learning.
Culture itself is a difficult phenomenon to define. Some behavioral scientists have proposed that the words “culture” and “tradition” should be considered synonyms (see Galef 1992 for a review), whereas others treat tradition as neither necessary nor sufficient condition for culture (McGrew 2004). How to treat “animal culture” much depends on its definition. Many definitions in the literature attribute cultural traits only to humans. At the other end of the scale is considering culture as a “meme pool” (sensu: Dawkins 1976) in populations which can include all cases of the regular use of public information in populations basing on relatively simple forms of social learning (Laland and Brown 2002). Given this situation, Lycett (2011) has suggested that animal culture may usefully be characterized as an emergent property of the “descent with modification” (sensu: Darwin 1859) process mediated by the combination of variation, social learning, and sorting.
Many animal behaviorists agree that cultural behavior in animals includes a package of behaviors rather than single traditions such as “bottle opening” by British birds (see Lefebvre 1995, for a review). Defining animal culture as a set of socially transmitted behavioral patterns, the working description given by Nishida (1987) is useful: “Cultural behaviour is defined as behaviour that is: (a) transmitted socially rather than genetically; (b) shared by many members of the group; (c) persistent over generations and (d) not simply the result of adaptation to different local conditions.”
The notion of animal culture dates back to Charles Darwin who was the first to suggest what became known as social learning and imitation in animals. The association of animal behavioral actions with the actual word “culture” was firstly brought forward with the discovery of socially transmitted food habits (“potato washing”) in macaques made by Japanese primatologists in the 1940s (see: Nishida 1987).
The possibility of culture in chimpanzees, the most “cultural” after our own species, surfaced early in Jane Goodall’s (1964, 1986) studies, stimulated by youngsters’ intense observations of skilled adult tool use. Studies at other sites later began to map local behavioral variations including as many as 39 behavioral patterns across Africa. Some of them concern tool use, such as ant-dipping, termite-fishing, nut-cracking, honey-dipping, drinking water with leaves, and so on. Others concern characteristic behavioral habits such as rain dances, handclasp grooming, details of courtship rituals, and so on. The researchers found no evidence that habits vary more between, than within, the three existing subspecies of chimpanzees. So genetic cannot account for the observed variability (Whiten et al. 1999; Whiten 2007; McGrew 2010).
Recent studies of animal traditions have taken the chimpanzee research as a template, and the following steps to identify cultural traditions have been elaborated: (1) show that behavioral differences between populations are not consistent with genetic explanations; (2) check that the behavioral differences cannot be explained by ecological factors such as availability by suitable raw materials for making tools; (3) study the transmission processes used by animals in controlled experiments: Can they learn by watching others? If so, what kind of things do they learn?
Ethologists have investigated the problem of animal culture for decades but only in the last years has a clear picture of cultural diversity in several species begun to emerge (see Reznikova 2007, for a review). Chimpanzees display the highest level of manufacturing ability but they are not the only nonhuman species which possess elements of “material culture.” Thirty years of field observations of the Southeast Asian orangutans have enabled an international group of researchers to reveal 24 examples of behaviors that have been defined as cultural variants, and among them using sticks to dig seeds out of fruit and to poke into tree holes to obtain insects, using leaves as napkins or as gloves, and so on (van Schaik et al. 2003).
Marine mammals can also be added to the catalogue of “cultural” animals. In Shark Bay, Australia, bottlenose dolphins apparently use marine sponges as foraging tools. Dolphins have devised a way to break sponges off the sea floor and wear them over their snouts as a kind of gloves to protect their sensitive rostrums when they probe for prey in the substrates (Krützen et al. 2005). The DNA analysis showed that the spongers were closely related, probably descending of a recent “Sponging Eve.” However, the pattern of sponging among the dolphins could not be explained by a “gene for sponging.” The researchers conclude that this behavioral pattern is culturally transmitted, presumably by mothers teaching their skills to their calves. Tool use is the most amazing but not the only population-specific behavioral trait that enables cetacean biologists to claim that marine mammals possess culture or at least traditions. Mann and Sargeant (2003) have listed many population-specific patterns concerning foraging strategies, styles of diving, patterns of social interactions, and many of them have been clearly demonstrated to be transmitted by means of social learning.
Such studies are becoming taxonomically more diverse, extending to social and foraging patterns among capuchin monkeys (Perry and Manson 2008), Japanese macaques’ stone-play habits (Leca et al. 2007), and variations in bower-birds’ decoration preferences (Madden 2008). The new study may reinforce bridge-building between the work of those focused on human and nonhuman forms of culture and further the exciting prospect of a more integrated “science of culture” (Whiten 2007).
However, there is much work to be done to understand which factors limit and which favor the acquisition of new behavioral traditions in animal communities. The main methodological difficulty on the way of studying animal culture is to recognize innovations in the field. Even when the origin of a certain innovation had been observed, it is difficult to predict a living trajectory of this innovation. Of many innovative behaviors observed, only a few will be passed on to other individuals, and seldom will they spread through the whole group. For example, Goodall (1986) observed two instances of the use of stones by adolescent chimpanzees to kill dangerous insects. She supposed that this usage of stones would become customary in that reference group. But this had not happened since, and the innovation faded away. All these incite researchers to search for reasons why some innovations are supported in animal communities while others are not.
Given the suggestion about the genetic predisposition of animals to learn certain behaviors much easier than others, Reznikova and Panteleeva (2008) considered a previously unknown way of propagation of behavioral traditions in animal communities using hunting in ants as an example. The authors suggest that distributed social learning plays an important role in spreading new traditions in animal communities: initial performances by a few carriers of an “at once and entirely” available behavioral pattern propagate this pattern among specimens which have only dormant “sketches” of it, and thus are genetically predisposed to learn the whole pattern. Spread of these behaviors in populations is based on relatively simple forms of social learning such as social facilitation which underlies species’ predisposition to learn certain sequences of behavioral acts. To be triggered, carriers of dormant “sketches” of a relevant behavioral pattern should encounter performances of this pattern with sufficient frequency. This strategy can be called “triggering of dormant behavioral patterns.” In principle, it could be useful for populations to have dormant “sketches” of complex behavioral patterns being implemented in several carriers and then spread by means of simple forms of social learning under suitable circumstances.
In general, “culturing” and social learning are based on differences existing between members of animal communities, that is, on behavioral specialization in populations, and in some situations, on cognitive specialization of individuals (see the entry “Altruistic Behavior and Cognitive Specialization in Animal Communities” in this volume). This returns us to the Darwin’s characterization of evolution which is based on the variation between individuals.