The Century of Great Ape Culture
In the past, I have discussed some of the biggest chimpanzee culture discoveries in The Ratchet. Many of the landmark discoveries were made in the 20th century. This culminated in 1999 with a behavioural synthesis of 20th century chimpanzee cultural data throughout Africa (Whiten et al. 1999). This research stimulated other primatologists to test whether cultural behaviour was exhibited within other great ape species. As a result of this research, the 21st century has been a century of great ape culture discovery. These discoveries are forcing us to reconceptualize our understanding of the great apes and ourselves. There is no more question of whether our closest relatives are cultural, the focus has shifted to understanding the evolution and variation of cultural behaviour.
There have been far fewer studies conducted to understand cultural behaviour of bonobos, orangutans, and gorillas vis-à-vis chimpanzees. Gorilla culture is perhaps the least understood. Most of our knowledge of gorilla culture comes from a groundbreaking study by primatologists Thomas Breuer, Mireille Ndoundou-Hockemba, and Vicki Fishlock, revealing that gorillas make tools that are partially inspired by ecological problems they face in certain habitats (Breuer et al., 2005). The team reported two interesting cases of gorilla tool use:
a) An individual utilizing a branch to test water deepness and stabilize herself during a river crossing
b) An individual using a trunk from a small shrub as a bridge to cross a deep swamp
This study shows that we may have a lot more to learn about gorilla culture. Unfortunately, gorillas are extremely difficult to study in the wild. There are entire subspecies of gorilla that have never really been observed at all. For researchers, this makes understanding gorilla culture and cultural variation almost impossible. However, new motion-sensor camera traps are enabling scientists to design research studies that were impossible just a few years ago. It is possible that future research designed with these camera traps could allow us to learn more about gorilla culture. The 2005 paper by Breuer et al. (2005) makes me excited for the possibility of such a study.
Bonobos have been slightly less mysterious than gorillas. A study by Gottfried Hohmann and Barbara Fruth in 2003 partially uncovered the cultural world of our other most closely related relative. Hohmann & Fruth were inspired by the “Cultures in chimpanzees” study by Whiten et al. (1999) and wanted to know how many of the cultural variants described in chimpanzees were also present within Lomako’s bonobo population. By analyzing behavioural data between 1991 and 1998, they revealed that 14 cultural variants in chimpanzees are also present in bonobos. These include branch drag, leaf sponge, branch clasp, vegetation seat, aimed throw, and the hand clasp (Hohmann & Fruth, 2003). Although the study sample was considerably smaller than the one used by Whiten et al. (1999), this study raised the possibility that chimpanzees were more culturally complex than their sister species (Tennie, et al., 2009). If true, the implications of such a discovery would raise some interesting questions about the evolution of culture and the behaviour of our common ancestor with chimpanzees and bonobos. However, these results could also simply be a product of the fact that there are more chimpanzees that inhabit a wide and diverse number of ecological niches.
Finally the orangutan, the lone Asian great ape, has also provided researchers with impressive evidence of cultural behaviour and variation. In fact, the geographic variation of cultural traditions among orangutans may most closely parallel those observed in chimpanzees. In 2003, Carel P. van Schaik and a team of researchers revealed that there was a strong correlation between geographic distance and cultural distance among orangutan populations (van Schaik et al., 2003). Surprisingly, this correlation may even be stronger than that observed among chimpanzee populations throughout Africa (Tennie et al., 2009). Also, orangutan tool use has proven to reveal some of the most unique functions in the entire animal kingdom, including autoerotic tool-use, leaf napkin, branch swatter, seed extraction tool-use, sun cover (building a cover for a nest on bright sunny days) and branch scoop (drinking water from a deep tree hole using a leafy branch) (van Schaik et al., 2003).
Of course, all of these data indicate that many 20th century academics were wrong about culture being a defining aspect of our species. Culture appears to be ubiquitous among the great apes, and widespread throughout the animal kingdom. There is now evidence for large-scale patterning of culture within and between populations, and entire communities appear to possess suites of cultural behaviours (Whiten et al., 2003). Furthermore, just like humans, culture allows the great apes to flexibly shape their environment (Breuer et al., 2005), gain access to resources (Sanz & Morgan, 2009), develop subcultures (Boesch, 2003), and share meaning (e.g., Hohmann & Fruth, 2003).
The fact that culture is present in all great apes increases the likelihood that the capacity for culture within our lineage may have been present as late as 14 million years ago (van Schaik et al., 2003). And studies on some monkey species have suggested that it could have been present as early as 35 million years ago (Visalberghi et al., 2009). However, despite the fact that modern primatological inquiry has revealed startling similarities between human and great ape culture, more research needs to be done in order to understand the mechanisms that enable novel behaviours to be learned (Hrubesch et al., 2009).
Also, if we are not the only cultural species, what makes us so different? I have hinted at what primatologists have learned about this perplexing question, and I will be exploring those ideas in great detail in the near future.