Evolving Intelligence: How Chimpanzees Master Tools Well Into Adulthood

Wild western chimpanzee using a stick tool to extract high-nutrient food. Credit: Liran Samuni, Taï Chimpanzee Project (CC BY 4.0)

A study in PLOS Biology reveals that chimpanzees continue to refine their tool-use skills into adulthood, similar to humans, suggesting that lifelong learning is vital for the evolution of complex tool use and cognitive development in primates.

Chimpanzees continue to learn and hone their skills well into adulthood, a capacity that might be essential for the evolution of complex and varied tool use, according to a study publishing today (May 7^th) in the open-access journal PLOS Biology by Mathieu Malherbe of the Institute of Cognitive Sciences, France and colleagues.

Humans have the capacity to continue learning throughout our entire lifespan. It has been hypothesized that this ability is responsible for the extraordinary flexibility with which humans use tools, a key factor in the evolution of human cognition and culture.

Human and Chimpanzee Learning Compared

In this study, Malherbe and colleagues investigated whether chimpanzees share this feature by examining how chimps develop tool techniques as they age. The authors observed 70 wild chimps of various ages using sticks to retrieve food via video recordings collected over several years at Taï National Park, Côte d’Ivoire.

As they aged, the chimps became more skilled at employing suitable finger grips to handle the sticks.

Continuous Skill Development

These motor skills became fully functional by the age of six, but the chimps continued to hone their techniques well into adulthood. Certain advanced skills, such as using sticks to extract insects from hard-to-reach places or adjusting grip to suit different tasks, weren’t fully developed until age 15.

This suggests that these skills aren’t just a matter of physical development, but also of learning capacities for new technological skills continuing into adulthood.

Insights into Evolutionary Learning

Retention of learning capacity into adulthood thus seems to be a beneficial attribute for tool-using species, a key insight into the evolution of chimpanzees as well as humans. The authors note that further study will be needed to understand the details of the chimps’ learning process, such as the role of reasoning and memory or the relative importance of experience compared to instruction from peers.

The authors add, “In wild chimpanzees, the intricacies of tool use learning continue into adulthood. This pattern supports ideas that large brains across hominids allow continued learning through the first two decades of life.”

Reference: “Protracted development of stick tool use skills extends into adulthood in wild western chimpanzees” by Mathieu Malherbe, Liran Samuni, Sonja J. Ebel, Kathrin S. Kopp, Catherine Crockford and Roman M. Wittig, 7 May 2024, PLOS Biology.
DOI: 10.1371/journal.pbio.3002609

Author Countries: France, Côte d’Ivoire, United States, Germany

Funding: This study was funded by the Max Planck Society (M.IF.EVAN8103 – to CC and RMW through the Evolution of Brain Connectivity Project). LS was supported by the German Research Foundation (DFG, Emmy Noether Fellowship 513871869). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.