Decoding Gorillas’ gestures: Insights into primate communication

The ability to communicate is a cornerstone of social interaction, whether among humans or our closest living relatives. A recent study by Jacques Prieur, Katja Liebal & Simone Pika in Scientific Reports delves into the complex and flexible communication system of Western lowland gorillas.

The research reveals that these great apes not only use gestures as a means of social negotiation but also adapt their communicative styles to suit their social contexts — which uncovers a fascinating parallel to human language and accents.

Gestures as social negotiation tools

Western lowland gorillas (Gorilla gorilla gorilla | yes that really is their scientific name) are social animals, living in groups where effective communication is crucial for maintaining harmony and coordination. Researchers Jacques Prieur, Katja Liebal, and Simone Pika investigated how these gorillas initiate play-fighting using gestures.

The study showed that gestures are not random; rather, they are intentional, goal-directed, and their form can vary depending on the individual’s social relationships and the context of interaction.

What sets this study apart is the discovery that for the first time nonverbal communication can carry distinct characteristics — akin to regional accents in human speech — which vary depending on the group’s geographic location. This dynamic flexibility underscores the gorillas’ cognitive sophistication and their capacity for adaptive social behavior.

Evolutionary implications

Understanding gorilla communication offers profound insights into the evolutionary trajectory of human language. The use of gestures as a primary communication tool might represent a precursor to spoken language. Moreover, the study highlights the role of social negotiation in shaping communication systems, providing clues about the pressures that might have driven the emergence of complex language in humans.

Challenges and insights from the field

Observing gorillas in naturalistic or semi-wild settings presents its own set of challenges. These include environmental variables, the need for non-intrusive methods, and the sheer complexity of analyzing nuanced behaviors in a dynamic social environment.

One particularly challenging aspect was deciphering the subtle differences in gestures — distinguishing between a playful “arm wave” and a similar gesture meant to assert dominance. The use of video recordings and systematic analysis was critical here, allowing the team to compare gestural forms within and between gorillas, revisit and cross-validate the observations.

Data collection: A behavioral scientist’s toolbox

Conducting such a detailed study of gorilla gestures requires to follow a rigorous approach to observe, collect and analyze behavioral data. The researchers employed systematic coding methods to analyze hundreds of hours of video footage. Noldus’ The Observer XT facilitated this work by enabling precise and efficient behavioral coding and analysis.

One notable feature that supports collaborative research efforts is the use of coder licenses in The Observer XT. Coding behavioral data is a time-intensive task, and multiple researchers working on the same project can significantly enhance efficiency and reliability.

With a coder license, students and researchers can contribute to a project using a predefined coding scheme and original video footage. Their coded data can then be compiled in The Observer XT and compared in a reliability analysis, ensuring robust and reproducible findings.

In this way teams can streamline their workflow while maintaining data integrity, and this functionality is particularly useful in large-scale behavioral research, where multiple observers work on different sections of a study.

Applications beyond the jungle

The implications of this research extend far beyond understanding gorillas. By shedding light on the cognitive and social underpinnings of communication, this work has potential applications in fields such as linguistics, anthropology, and even artificial intelligence. For instance, the core principles of gestural communication could inform the development of more naturalistic human-computer interactions.

Additionally, these findings might help refine rehabilitation protocols for primates in captivity, ensuring their social and psychological needs are met by incorporating knowledge of their complex social life and communication systems.

Key takeaways for researchers

For researchers in behavioral science, this study exemplifies the power of combining detailed observational methods with powerful analysis tools. Here are a few takeaways:

• Nuance matters: Small variations in behavior can have significant communicative value, emphasizing the need for precise data collection and analysis.
• Context is key: Behavioral patterns should always be interpreted within their social and environmental contexts to uncover their true significance.
• Invest in methodology: Leveraging tools that enhance data accuracy and efficiency, such as behavioral analysis software and coder licenses, can elevate the quality of research and can make life easier for researchers.

Final thoughts

This study on Western lowland gorilla communication enriches our understanding of primate cognition and social behavior, bridging the gap between animal communication systems and human language. Noldus Information Technology is proud to support the scientific community with tools that facilitate such groundbreaking research.

Interview with one of the authors: Jacques Prieur

About your research and your inspiration. You are an expert in primate behavior.

What sparked your interest in specifically studying gorillas? How they communicate? And what is the relevance?And why did you choose Western lowland gorillas in this study specifically?

"I'm an expert in human and non-human primate behaviors. Studying them can help us to better understand ourselves, which is vital and fascinating.

Gorillas are less studied than the well-known chimpanzees, while they are just as scientifically interesting, more playful and pacific. I have more fun observing and studying gorillas than chimpanzees.

Gorillas are great apes, like humans. They communicate using a variety of vocal and non-verbal signals in a similar way to humans. Just look at how children play and how juvenile gorillas play as well, this is striking!

Gorillas are specifically relevant models for this study for three reasons:

1. they exhibit the largest gestural repertoire of all non-human great apes in terms of overall number and number per individual: 33–102 gesture types
2. the gorilla social structure is consistent with many features of human social organization such as certain patterns of parental behaviors (e.g. male parenting, family formation)
3. the gorillas differ from the very much studied chimpanzees in their ecology and their social structure and dynamics. Studying gorillas’ acquisition and development of gestural communication may thus provide crucial insight into how human development, communicative and social-cognitive skills are linked and related to social environment"

How does this study build on or differ from previous work in the field of primate communication?

"According to a growing number of researchers, human culture and language are closely related evolutionarily speaking. Gestures play a crucial role in human and non-human primate communication systems (see recent review Prieur et al. 2020 for more details). Studies on the acquisition of gestures in primates provided evidence for modulations of gesture type use in relation to signaller’s sociodemographic characteristics but what about modulations of gesture type morphology? The goal of our study was to tackle this question."

Prieur, J., Barbu, S., Blois‐Heulin, C., & Lemasson, A. (2020). The origins of gestures and language: history, current advances and proposed theories. Biological Reviews, 95(3), 531-554.

How did you ensure that your observations and analyses accounted for the natural variability in gorilla behavior?

"In an effort to avoid influencing the behavior of individuals and group, our study was purely non-invasive and involved only observations of naturally occurring spontaneous behavior, with audio and video recordings taken from a minimum distance of five meters."

If you used any software tools or systems (e.g., for data coding or analysis), what was your experience with them, and how did they impact your workflow?

"I already had experience with The Observer XT. Among other things, I used it to collect and analyze baboons’ behavior who communicated intentionally by pointing towards humans. I thus knew this research tool was very helpful."

Your findings suggest that gorilla gestures can be likened to human accents. Could you elaborate on what this means for our understanding of language evolution?

"These findings suggest that not only vocal but also nonverbal communication signals can be shaped by social factors such as group. This study supports the view that socioecological factors have shaped the evolution of complex signalling systems. It also highlights this important issue for future research: adoption of a multimodal and multifactorial approach. Addressing this issue should enable us to deepen our understanding of the complex of human and non-human primate communication systems."

What was the most rewarding or memorable moment for you during the study?

"Observing natural behavior of gorillas in their daily life. It was really fun and very interesting. Among other things, I observed and documented the first evidence of naturally occurring spontaneous exploitative behavior of a conspecific as a social tool for food acquisition in non-human animals (see Prieur & Pika 2020 for more details). I was literally speechless!"

Prieur, J., & Pika, S. (2020). Gorillas’(Gorilla g. gorilla) knowledge of conspecifics’ affordances: intraspecific social tool use for food acquisition. Primates, 61(4), 583-591.

If you had to summarize your research in one sentence for a non-scientific audience, what would you say?

"Curiosity is an engine of life, science is its essence, go for it!"