Discover the fascinating social rituals of our primate cousins
At the heart of these hello and goodbye exchanges lies what scientists call "joint commitment"—a mutual sense of obligation between individuals engaged in a shared activity.
According to lead researcher Raphaela Heesen from Durham University, this concept "bears witness of joint commitments. That underpins all kinds of joint interactions" and serves as "the glue of our success as a species" 1 .
What makes this discovery particularly significant is that joint commitment isn't just about the obligation itself, but the process of mutually establishing that agreement and acknowledging when it has been fulfilled 1 . This is why the intentional signals to begin and end interactions carry such importance—they represent the framework that supports cooperative endeavors, from brief grooming sessions to complex human projects.
Joint commitment requires both parties to acknowledge their shared activity and mutual obligations.
These rituals create the structure that enables complex social interactions and cooperation.
To understand how apes manage their social interactions, researchers embarked on an extensive observation study, meticulously documenting over 1,200 interactions between apes in zoo settings 1 .
The research team employed naturalistic observation of captive groups of chimpanzees and bonobos, carefully recording their social interactions using qualitative behavioral analysis 1 2 . This approach allowed them to:
The results offered fascinating insights into ape social intelligence:
Bonobos exchanged "hello" signals before playing
Chimpanzees exchanged "hello" signals before playing
Goodbye signals were even more common in both species, highlighting the importance of properly concluding interactions 1 . The gestures included touching each other, holding hands, and even butting heads, along with meaningful eye contact 1 .
| Gesture Type | Description | Species Frequency |
|---|---|---|
| Physical Touch | Gentle touching of hands, arms, or face | Common in both species |
| Hand Holding | Brief clasping of hands | More frequent in bonobos |
| Head Butting | Gentle head-to-head contact | More common in chimpanzees |
| Mutual Gaze | Intentional eye contact | Particularly important in bonobos |
Interactive Chart: Frequency of Hello/Goodbye Signals in Apes
The study revealed that ape communication isn't one-size-fits-all. The nature of relationships significantly influenced how interactions began and ended, mirroring human social nuance.
Heesen noted: "When they were interacting with a good friend, they produced shorter entry and exit phases... and they often didn't even communicate at the end of an interaction. And we know that from our daily lives too, right? If we're interacting with a good friend, we don't have that kind of politeness" 1 .
This relationship-dependent communication manifested in several ways:
| Relationship Type | Hello/Goodbye Elaboration | Similar Human Pattern |
|---|---|---|
| Close Friends | Minimal or absent signals | Skipping formalities with family |
| Different Social Status | More elaborate rituals | Formal workplace interactions |
| New Acquaintances | More deliberate communication | Polite greetings with strangers |
Minimal communication needed due to established trust and familiarity
More elaborate rituals to acknowledge social hierarchy
Deliberate communication to establish relationship parameters
These findings challenge long-standing assumptions about what makes human communication special. As Heesen explained, "We previously thought that humans were the only species that coordinate those entry and exit phases of interactions" 1 .
The discovery that apes share this capacity suggests that:
The evolutionary roots of human cooperation extend back at least 13 million years to our last common ancestor with bonobos and chimpanzees
Complex social cognition exists beyond humans, requiring us to rethink what separates our mental capabilities from other species
The building blocks of human language may have originated in these gestural communication systems
The research opens new questions about how widespread this behavior might be in the animal kingdom. As Heesen pointed out, this phenomenon "hasn't been systematically studied whether other species also take leave of each other like we do" 1 .
Studying ape communication requires specialized methods and approaches. Here are the key tools researchers use to decode these complex social behaviors:
| Research Tool | Function | Application in Ape Communication Studies |
|---|---|---|
| Behavioral Observation | Systematic recording of natural behaviors | Documenting gestures and social interactions |
| Video Analysis | Frame-by-frame review of interactions | Capturing subtle, rapid gestures |
| Focal Sampling | Following specific individuals | Tracking communication patterns |
| Qualitative Coding | Categorizing types of behaviors | Classifying different gesture types |
High-quality video recording allows researchers to analyze interactions frame by frame, capturing subtle gestures that might be missed in real-time observation.
Researchers develop detailed coding systems to categorize different types of gestures and social interactions, ensuring consistent analysis across observations.
The discovery that apes intentionally say hello and goodbye represents more than just a fascinating animal behavior—it provides a window into our own evolutionary past. These purposeful social rituals suggest that the human need to formally frame our interactions runs deep in our primate heritage.
As we continue to decode the complexities of animal communication, each gesture we document reminds us of our connection to the natural world. The next time you wave hello or say goodbye to a friend, remember that you're participating in a social ritual that transcends humanity—a fundamental practice of relationship management that we share with our primate cousins.
What other seemingly unique human behaviors might we discover in the animal kingdom? As this research shows, the line between human and animal capabilities grows increasingly blurred with each new discovery, inviting us to reconsider what makes us truly unique.
A Social Glue We Share
Imagine finishing a pleasant conversation with a friend and simply turning to walk away without a word. It would feel abrupt, even rude. That's because humans naturally signal the beginning and end of social interactions. Until recently, this complex social behavior was considered uniquely human. But groundbreaking research reveals our closest primate relatives—chimpanzees and bonobos—purposefully use "hello" and "goodbye" gestures too, suggesting these social rituals run much deeper in our evolutionary history than we ever imagined.
This discovery challenges long-held assumptions about what makes human communication unique and suggests the evolutionary roots of our social rituals extend back millions of years.