It may be surprising in a chapter on nonhuman primates to see a discussion of culture. After all, culture is considered by many, including cultural anthropologists, to be a distinguishing characteristic of humans. Indeed, some anthropologists question claims of culture in primates and other animals. Definitions of animal culture focus on specific behaviors that are unique to one population. Anthropological definitions of human culture emphasize shared ideology (e.g., values, morals, beliefs) and symbols, not just behavior. Using this definition, some cultural anthropologists view primates as lacking culture because of the absence of symbolic life (e.g., religion). However, the longer we study primate groups and populations, the more insight we gain into primate behavioral variation. If we define culture as the transmission of behavior from one generation to the next through social learning, then we must view at least some of the behavioral variation we see in primates as forms of cultural tradition, or a distinctive pattern of behavior shared by multiple individuals in a social group that persists over time (Whiten 2001).
Due to both their high level of intelligence and the large number of long-term studies on several different populations, chimpanzees provide the best example of cultural tradition in primates. Chimpanzees express cultural variation in multiple behavioral patterns, ranging from population-specific prey preferences and hunting strategies to tool-use techniques and social behaviors. For example, in Tanzania, chimpanzees fish for termites by stripping twigs and then poking the twigs into termite mounds. The termites react to the “invasion” by attacking the twig. The chimpanzee pulls the twig out, termites attached, and eats them. In Gambia, they use modified twigs to extract honey from holes in trees. In Fongoli, Sénégal, chimpanzees use sticks as “spears” that they stab into tree cavities to hunt for galagos (Figure 6.27). Multiple chimpanzee populations use a “hammer and anvil” to crack open nuts, but the specific techniques differ. Because the cultural traditions are so diverse and unique, if a researcher can observe enough of a chimpanzee’s behavior, it is possible to assign that individual to a specific community, much in the same way a human being can be associated with a specific culture based on his or her behavior (Whiten 2011).
How do chimpanzee cultures develop, and how does cultural transmission occur? Although we do not know for sure how chimpanzee cultural traditions develop initially, it is possible that different groups invent, either accidentally or deliberately, certain behaviors that other individuals copy. Immigration, or movement of an individual into a new group or community, is an important avenue of cultural transmission in chimpanzees, much as it is between human cultures. Immigrants (typically females) may bring cultural traditions to their new community, which residents observe and learn. Conversely, immigrants may observe and learn a cultural tradition practiced in their new community (Whiten 2011).
Two monkey species are well-known for behavioral variation that has been called “pre-cultural” by some primatologists: Japanese macaques and tufted capuchins (Sapajus apella). The transmission of unique foraging (the act of searching for food) behaviors through the members of a provisioned group of Japanese macaques on Koshima Island is well known (Matsuzawa 2015). In an effort to keep the monkeys nearby, researchers provided them with piles of sweet potatoes. A juvenile female named Imo spontaneously washed a muddy sweet potato in a stream. This new food-processing technique first spread among other juveniles and then gradually to older individuals. Within 30 years, it had spread across generations, and 46 of 57 monkeys in the group engaged in the behavior. Another example comes from a group living far to the north, in Shiga-Heights, Nagano Prefecture. Researchers used apples to entice Japanese macaques to the area. Within a few years, monkeys visited the area regularly and were observed playing with the water in the hot springs. Soon, they climbed into the hot springs and learned to immerse themselves to keep warm and reduce stress when not foraging (Figure 6.28; Matsuzawa 2018; Takeshita et al. 2018; recall also our discussion of hot spring use as an example of analogous traits at the beginning of this chapter). These examples share several characteristics with human culture, including invention or modification of behavior, transmission of behavior between individuals, and the persistence of the behavior across generations (McGrew 1998).