The evolutionary origins of human culture: a primatological perspective

Project Information

CULT_ORIGINS

Grant agreement ID: 101042961

DOI

10.3030/101042961

EC signature date 29 March 2022

Start date 1 July 2022

End date 30 June 2027

Funded under

• European Research Council (ERC)

Total cost

€ 1 500 000,00

EU contribution

€ 1 500 000,00

Coordinated by

UNIVERSITEIT UTRECHT
Netherlands

Periodic Reporting for period 1 - CULT_ORIGINS (The evolutionary origins of human culture: a primatological perspective)

Reporting period: 2022-07-01 to 2024-12-31

Summary of the context and overall objectives of the project

The Evolutionary Origins of Human Culture

Human culture, recognised as a cornerstone of our species' biological success, enables adaptability across diverse environments. Despite its importance, understanding its evolutionary roots remains a challenge. Culture, broadly defined as socially transmitted information, encompasses innovations that spread through social learning, facilitating behavioural flexibility and niche construction. Unlike genetic evolution, cultural evolution allows phenotypic changes within lifetimes, granting humans a unique adaptive edge.

Central to human culture are behavioural traditions shaped by social transmission. Traditions like greetings reflect cultural diversity but underscore a deeper adaptive function: shaping sociality—positive and negative interactions among group members. Social culture fosters fitness-enhancing behaviours such as cooperation and learning, which are pivotal for cumulative cultural evolution. This process, seemingly unique to humans, refines cultural expressions over time, aligning them with intended purposes.

From an evolutionary perspective, primates, our closest relatives, provide critical insights into the roots of human culture. Research in "cultural primatology" reveals primates as avid social learners, capable of transmitting traditions like potato-washing among macaques. However, this field has largely focused on material traditions, neglecting the socio-adaptive aspects crucial to understanding culture’s evolutionary origins.

The CULT_ORIGINS project proposes a transformative approach, examining social culture across 32 groups of three primate species. It hypothesises that primate sociality reflects cultural influences, evidenced by group-specific behaviors, stable social traits, and patterns of social transmission. Additionally, the project explores how social culture enhances cooperation, social learning, and innovation, potentially leading to cumulative cultural evolution. By integrating experimental and observational data, CULT_ORIGINS aims to uncover primate capacities for social culture and challenge the notion of human cultural uniqueness.

This research aligns cultural primatology with human studies, highlighting the need for a comparative approach to uncover the evolutionary origins of social culture. With primate populations facing extinction, understanding their cultural capacities is urgent. CULT_ORIGINS seeks to redefine our understanding of culture, bridging gaps in primate studies and offering insights into the traits that underpin human success.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Our research program is significantly advancing understanding of (social) culture in non-human primates, testing its flexibility and assessing whether primates accumulate culture like humans. By combining cutting-edge methods, interdisciplinary collaboration, and effective communication, we have reshaped perspectives on primate sociality and cultural transmission.

1. Identifying Social Culture in Non-Human Primates
We documented socially transmitted behaviours, including rhesus macaques hacking touchscreen software—an innovation spreading through social learning despite lacking functional benefits. Using thermal imaging, we linked social learning to emotional arousal, revealing its role in cultural transmission. Employing customised YOLO algorithms, we automated pose estimation to analyse macaque social networks with unprecedented precision. Our study of 16 Pan ape groups, published in *iScience*, challenged assumptions of species-typical behaviours, showing that group-specific dynamics are key to understanding primate culture.

2. Testing Cultural Flexibility
To assess cultural flexibility, we developed statistical tools that disentangle individual, dyadic, and group-level behavioural variations. Applied to six bonobo communities (*Evolutionary Human Sciences*), these tools revealed significant group-specific differences, challenging the notion of species-typical bonobo behaviour and drawing parallels with human societies. Our *Nature Human Behaviour* study refuted the Zone of Latent Solutions hypothesis, providing robust evidence of copying behaviours in chimpanzees and demonstrating their cultural adaptability.

3. Assessing Cumulative Culture
Preliminary findings from four chimpanzee groups indicate they may modify and build upon behaviours, suggesting cumulative culture. Complementary research on rhesus macaques revealed the transmission of novel behaviours, offering insights into potential cumulative processes. These findings were featured in an award-winning conference poster and will be presented at the Culture Conference 2025.

Our innovations include advanced pose-estimation technology for tracking social interactions, thermal imaging to study emotional drivers of learning, and statistical tools to rigorously test cultural hypotheses.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Our research programme has advanced the study of primate behaviour, challenging conventional paradigms and providing critical insights into social and cultural variation among non-human primates.

**Breakthroughs in Rhesus Macaque Studies**
Using automated deep learning, we are extracting detailed social network data from rhesus macaques, enabling precise mapping of interactions and group dynamics. This foundational work supports the study of cultural transmission in non-human animals. Complementary to this, experimental tests on cooperation in two macaque groups are revealing the social mechanisms underpinning cultural behaviours. Additionally, social tolerance data collected from ten groups have uncovered intriguing patterns of intraspecific variation, influenced by environmental and social factors.

A notable innovation we observed in rhesus macaques is their ability to hack touchscreen software, a behaviour that spread socially within the group. Thermal imaging revealed emotional arousal linked to this hacking, suggesting primates experience excitement during social learning. This non-adaptive yet socially transmitted behaviour exemplifies the complexity of primate social learning. This study is under presubmission review at *Nature* and will focus on its implications for understanding cultural processes.

**Challenges to Prevailing Theories**
In *Nature Human Behaviour*, we published a robust critique of a widely accepted theory on chimpanzee behaviour, introducing new methodologies and providing the first substantial refutation of this framework. This work is poised to become a cornerstone for improving behavioural science methodologies. Similarly, in *Evolutionary Human Sciences*, we explored behavioural variation across six bonobo communities, revealing significant group-specific differences. This study challenges the assumption that bonobo behaviours are species-typical, drawing parallels to cultural diversity in human societies.

**Pan Ape Studies and Group-Level Variation**
Our publication in *iScience* tested 16 groups of Pan apes (chimpanzees and bonobos) using novel measures of social tolerance. Contrary to species-centric interpretations, we found negligible species-wide differences but significant group-level variation, emphasising the role of group dynamics in shaping behaviour.

Through these achievements, our programme has enriched understanding of primate social behaviour, developed new methodologies, and deepened insights into the cultural dimensions of primate societies.