The two non-human ape species that will be discussed in this essay include: orangutan (Pongo pygmaeus) and gorilla (Gorilla gorilla). The word culture can have a very loose definition, resulting in anthropologists expressing their views on what culture in Homoinoidea is in different ways. Ranging from a limited definition to broad. Culture tends to be commonly thought of by cultural anthropologists as to be specific to humans, reserving the term to “the wide range of phenomena including norms, values, shared meanings, and patterned ways of behaving” (Birukou, et al., 2009). On the other hand, biological anthropologists have created a more inclusive definition whereby, “the significance of cultural transmission is recognized as one of only two important processes that can generate evolutionary change: inter-generation transmission of behaviour may occur either genetically or through social learning, with processes of variation and selection shaping biological evolution in the first case and cultural evolution in the second.” (Whiten, et al., 1999). This essay will predominantly use the latter’s definition of culture. More specifically, focusing on cumulative culture, cultural content, and social learning processes of orangutans and gorillas.
Food cleaning is an example of a cultural behaviour performed by the orangutan species (Allritz, et al., 2013). While it is also common amongst other nonhuman primates such as Japanese macaques, bonobos (Pan paniscus), and that of the great apes, the act is therefore not unique to orangutans (Allritz, et al., 2013). Food cleaning involves the washing of food before consumption in order to remove dirt and other unwanted substances on said food (Neadle, et al., 2017). The article ‘Food washing and placer mining in captive great apes’ notes that caretakers in Leipzig Zoo claimed that when food was presented to orangutans and gorillas, both species would bring food to water and rinse prior to eating it (Neadle, et al., 2017). However, the study that the authors conducted, found that all captive groups, other than gorillas, would perform food cleaning in solitary and did not require social learning to do so (Neadle, et al., 2017). This would be an example of non-cumulative culture where the act could benefit from social learning, however, was not created through social learning. There are few studies that record food cleaning outside of captive conditions, possibly due to the fact that many non-human primates find food amongst canopies. On the contrary, the journal article ‘Food cleaning in gorillas: Social learning is a possibility but not a necessity’ conducts research on two types of gorillas; Western lowland gorillas (Gorilla gorilla gorilla) and Mountain gorilla (Gorilla gorilla beringei). Food cleaning has been observed amongst western lowland gorilla, however, not documented in mountain gorillas (Neadle, et al., 2017). The failure of mountain gorillas to perform food washing is due to the ecology in which mountain gorillas live as there is a lack of dirty fruit in its environment (Neadle, et al., 2017). Gorillas diet of little fruit and instead leaves and piths would be another factor (Neadle, et al., 2017). There is also no evidence based research where lowland gorillas require social learning to wash food (Neadle, et al., 2017).
Orangutans are found to be very solitary nonhuman primates (Dindo, et al., 2011). Foraging in groups of rarely no more than three (Mitani, et al., 1991). For this reason, there is less observational research on this species. There are many benefits to the gathering of nonhuman primates. Reasons include; there is an increased number of potential mates, protection from predators, and it encourages bonds between infants and mothers, as well as learning within species (Schaik, 1999). As orangutans are found to be solitary, this decreases the amount of opportunities orangutans could learn from others. Despite this, the paper ‘Observational learning in orangutan cultural transmission chains’ discovered that using the diffusion chain experiment; individual orangutans learn how to forage by the means of observing other orangutans (Dindo, et al., 2011). However, when adult male individuals come into contact with other adult male orangutans, there sometimes may be an intense aggression towards each other (Fleagle, 1998). This interaction would involve confrontational vocal exchanges and occasionally physical. When adult male orangutans do contact other orangutans, this is done so through loud callings (Fleagle, 1998). Contrarily, the relationship that adult female orangutans have with other orangutans involve the exclusive raising of infant orangutans and foraging with young male orangutans (Fleagle, 1998). Female orangutans will teach infants through social learning in small home areas that overlap with male orangutan’s large home areas (Fleagle, 1998). In contrast, gorillas form in groups of nine or ten with an alpha male of a silverback mature adult male and several females, offspring and younger males (Fleagle, 1998). Gorillas will then travel as a group throughout the day with small home areas (Fleagle, 1998). In Ganas & Robbins 2005 study, the size in which gorillas travelled in is positively correlated with the number of gorillas in a group (Ganas & Robbins, 2005). If the daily home size doesn’t increase as the group size increases, then the necessary requirement of food resources to gorillas within the travelling group cannot be met (Ganas & Robbins, 2005). When this happens, there is a decreased level of reproductive success in female gorillas (Watts, 1990).
Mountain gorillas foraging behaviour involves the destruction of vegetation that rapidly regenerates (Fleagle, 1998). Lowland gorillas will consume more fruit than mountain gorillas due to its ecology, while mountain gorillas will consume leaves and piths (Fleagle, 1998). As a result, there has been found to be a lack of comprehensive tool usage within gorillas, this is possibly due to its diet and ecology, where the food mountain gorillas eat do not require tools (van Shaik, et al., 1999). Even in captivity, the use of tools in gorillas has not been documented (van Shaik, et al., 1999). Contrastingly orangutans use tools on a regular basis as a means to aid in the extraction of food for insects and nuts (van Shaik, et al., 1999). These feeding tools are beneficial, however, whether or not orangutans use feeding tools is dependent on the amount of food that requires extraction in the orangutans surrounding ecology (van Shaik, et al., 1999). Orangutans also require social learning in order to create feeding tools (van Shaik, et al., 1999). When there is a lack of social learning in orangutans, there has then been found to be a lack of tool usage as opposed to a lack of environmental factors (van Shaik, et al., 1999). This is potentially due to the fact that many of the skills that are required to create and use tools are typically too complex to develop without social learning. Foraging behavior within female orangutans require the use tools, but also, in order to maximize food resources, females tend to separate from larger male counterparts (Fobes & King, 1982). This is in order to minimize conflict with male orangutans when foraging for food (Fobes & King, 1982). Orangutans have been found to create other tools such as sticks to scratch and the use of leaves to wipe body parts (Wich, et al., 2010). On the other hand, there is little to no research carried out on tool usage amongst gorillas in non-captive conditions. The study ‘First Observation of Tool Use in Wild Gorillas’ conducted observational research in a swampy forest of the northern Congo (Breuer, et al., 2005). The article describes use of a stick to uphold posture when navigating through the swamp, suggesting that a negative incident may have happened without the use of this tool when in the swamp (Breuer, et al., 2005). The use of the stick is specific to its own ecology as is not found in other gorillas (Breuer, et al., 2005). Thus, this does not require social learning and instead is an example of non-cumulative culture. However, gorillas that live in this environment could benefit from social learning. In captive conditions, gorillas were noted to use two hands to consume food (Parker, et al., 1999). The use of two hands by primates is also known as bimanualism (Parker, et al., 1999). Gorillas would also use complex cognition in order to produce tools such as a stick to rake for food (Wood, 1984).
While the topic of communication and language is constantly debated in the science community in relation to non-human primates. A reciprocation of sounds and actions between these groups cannot be ignored. There has been an increasing number of studies regarding gestural communication. Orangutans have been found to gesture intentionally to communicate messages with meanings (Russon & Andrews, 2010). For example, an Orangutan named Chantex jointly held a thumb and finger to represent a balloon, whilst Koko the gorilla pretended to roll a ball between hands to symbolize clay (Russon & Andrews, 2010). Russon and Andrews findings report that orangutans may use gestures to represent items, actions, thoughts with the purpose of revealing intentions, theft, and asking for assistance (Russon & Andrews, 2010). Orangutans will also make a kiss-squeak sound as a distress signal. This simultaneously is used to mislead predators into thinking that the orangutan is that of a bigger size (Lameira, et al., 2013). Gestural communication is also commonly documented amongst gorillas (Pika, et al., 2013). In the study ‘Gestural Communication in Young Gorillas (Gorilla gorilla): Gestural Repertoire, Learning, and Use,’ 33 gestures were compiled. These would include visual and sound gestures (Pika, et al., 2013). Several gestures were flexible, whereby said gestures would express food and recreation, while others required a response (Pika, et al., 2013). Visual gestures would be considered more tactile, while auditory more direct and important (Pika, et al., 2013). Depending on which gestures gorillas use would be based on the situation (Pika, et al., 2013). However, the paper did not document any gestures relating to dangerous situations unlike Lameira, et al.’s 2013 article, where orangutans do have gestures regarding warnings.
The cultural behaviors carried out by both orangutans and gorillas were found to be diverse, unique within both species and complex. Each engaging in cultural behaviors that would be incredibly beneficial. Examples of such actions carried out and mentioned in this essay allowed for food cleaning, the use of tools to maximize food consumption, as well as communication in order to convey messages and meanings. Throughout the writing of this essay, the realization that there is little information on the observation of gorillas in the wild was noted. Certain cultural behaviors did not require social learning, but instead, were specific to its own ecology. As a result, many behaviors are determined socially and by ecology. All examples of behaviors above, express cumulative culture as well as noncumulative culture, cultural content, and social learning processes. Both orangutans and gorillas engage in these behaviors and typically learn these through social learning processes from strong mother – infant relationships or from other male counterparts within group.