Nonhuman Primates’ Stone Age Revolution

Figure 1: South American Capuchin monkey using stone to crack open a nut (Credit: Dave Watts)

Humans (aka, Homo sapiens) are considered very unique in several ways.  We are the only species that has developed complex cultures, we are the only species that uses language, and we are generally considered the paramount species.  For all of our uniqueness researchers are beginning to realize that the traits that set us apart are actually not that different from several other animal species.  Today’s blog post will highlight this point by exploring the recent contemporary and archaeological evidence that covers the Stone Age innovations and accomplishments by nonhuman primate species.  This will be explored further by addressing what the term “Stone Age” means, followed by discussions on the contemporary and archaeological evidence that demonstrates how specifically nonhuman primates are meeting these criteria.

First, it is important to understand exactly what a “Stone Age” entails.  From a human perspective it is associated with the first definitive use of stone tools and the various other cultural innovations that go with it.   Stone tools were first definitively used by our hominid ancestors over 2 million years ago, starting with Homo habilis and their Olduwan stone tool traditions.  Subsequent species of hominids that evolved after Homo habilis built on this foundational knowledge and technology to create more complex stone tools, and with these innovations were various other cultural innovations, such as the control and manipulation of fire, the creation of jewelry and art, and purposeful hunting and fishing activities. 

When the term “Stone Age” is discussed in conjunction with nonhuman primates, however, it takes on a different meaning.  It simply refers to the use of stones (aka rocks or lithics) by nonhuman primates.  Typically, the use of stones among these species are to collect and obtain food, specifically as stones have been used to dig out or smash open food stuffs.  At the present time there have been no further cultural developments related to the “Stone Age” innovations observed among nonhuman primates.

Figure 2: Long tailed macaque in Thailand using a rock to open shellfish (Credit: Mark MacEwen)

 

Second, various nonhuman primate species have been observed creatively utilizing their natural resources to meet their intended goals.  Various ape species (e.g. gorillas, orangutans, bonobos, and chimpanzees) have been observed using leaves and sticks to fish out ants and termites, build nests, create weapons to kill and eat smaller primate species, and even draw attention to themselves for the purposes of engaging in sexual intercourse.  None of this is new information.  What is new, however, is the use of stones to acquire food (Figures 1 & 2).  Various nonhuman primate species, including but not limited to ape species, have been observed using stones to crack open nuts and shell fish to gain access to the food within the shells.  These species have also been seen using stones to dig out tubers and roots for nourishment.  This is unprecedented behavior, particularly among monkey species such as macaques and capuchins, who while intelligent are not necessarily seen as sophisticated as ape species. 

These are, however, not the only evidence that has shocked the anthropological community.  Beginning in 2007 there have been a series of published findings that have opened up a new avenue of research referred to as primate archaeology, wherein archaeological methods and theory are used to investigate primate material culture evidence of the distant past.  Studies in Western Africa and Northeastern Brazil have demonstrated definitive evidence that both chimpanzees and capuchins utilized stone tools for thousands of years, solely for the purposes of acquiring food resources.  This sets the timeline back for the nonhuman primate “Stone Age” Revolution thousands of years, but it also places the more recent evidence in context.  Nonhuman primates have had the ability to utilize stone tools, although their use has been dependent on need.

What does this mean in the great scheme of things?  Should humans be worried about a literal nonhuman primate take over as illustrated in the series, “Planet of the Apes”?  The simple answer at this time has and remains no.  Part of the reason why nonhuman primates have not been observed utilizing stone tools regularly is that many species are arboreal, meaning they live in trees.  Stone is not readily available in the forest canopies, meaning they just have not had a need to use stones as much as humans have had that need.  Second, the use of stone tools creates noise, which for most nonhuman primates is a noisy beacon that attracts predators, and nonhuman primate species do not want that.  Only when there is a need and little risk do nonhuman primate species utilize stone tools. 

This does not mean that these innovations are not without merit.  They provide researchers opportunities to gain better understandings of the circumstances that may have driven our hominid ancestors to develop stone tools.  As our hominid ancestors no longer exist today and therefore cannot be observed in their natural settings performing their typical tasks nonhuman primates provide a suitable analogy to allow for the study of human behavioral (and in this case, cultural) development.  This is what makes this discovery so special, and as more attention is paid to these areas of research more information about what modern nonhuman primates and premodern humans are and were capable of will come to light, providing us greater insights into what it means to be a primate.

References

Barras, C. (2015, August 18). Chimpanzees and monkeys have entered the Stone Age. Retrieved from BBC: http://www.bbc.com/earth/story/20150818-chimps-living-in-the-stone-age

Bower, B. (2019, June 24). Capuchin monkeys’ stone-tool use has evolved over 3,000 years. Retrieved from Science News: https://www.sciencenews.org/article/capuchin-monkey-stone-tool-use-evolution-3000-years

Kaplan, S. (2018, July 6). These tiny monkeys have entered their Stone Age with a bang. Retrieved from Washington Post: https://www.washingtonpost.com/news/speaking-of-science/wp/2018/07/06/these-tiny-monkeys-have-entered-their-stone-age-with-a-bang/

Mercader, J., Barton, H., Gillespie, J., Harris, J., Kuhn, S., Tyler, R., & Boesch, C. (2007). 4,300-Year-old chimpanzee sites and the origins of percussive stone technology. PNAS, 3043-3048.