Chimpanzees’ Remarkable Memory Reveals Strategies for Finding Hidden Food

Chimpanzees, humanity’s closest living relatives, are renowned for their exceptional cognitive abilities. While much is known about their complex memory use in locating seasonal fruits, less attention has been given to how they solve challenges related to finding animal-based food sources. A groundbreaking study1 now reveals how wild chimpanzees use both spatial and episodic-like memory to locate elusive underground ant nests, showcasing their sophisticated mental strategies and offering a glimpse into the evolution of cognitive abilities in our lineage.

Memory and Foraging: A Cognitive Feat

Conducted by researchers from the University of Barcelona and the Jane Goodall Institute Spain, the study focused on the chimpanzees of Senegal’s Dindefelo Community Nature Reserve, where the primates hunt army ants (Dorylus spp.). These ants, rich in protein and minerals, are a crucial dietary component but are notoriously difficult to find due to their hidden nests beneath rocks, roots, and vegetation.

“Ant nests are scarce and nearly impossible to see,” explains Andreu Sánchez-Megías, the study’s lead author. “For chimpanzees, remembering the exact location of a nest is an effective foraging strategy.”

The researchers observed 679 chimpanzee visits to four different ant nests between 2018 and 2022. Their findings, published in Communications Biology, reveal that chimps rely on a combination of memory types and sensory skills to locate these food sources.

Spatial and Episodic-Like Memory in Action

The study highlights the chimpanzees’ use of two distinct types of memory:

• Spatial Memory: Chimpanzees recall the precise locations of ant nests, often returning to them even after long absences.

• Episodic-Like Memory: The apes also remember past experiences at these sites, such as whether the nests contained ants during previous visits. This ability closely resembles human episodic memory, which involves recalling the “what,” “where,” and “when” of events.

Episodic-like memory is distinguished from human episodic memory by the absence of verbalization. However, it represents a significant cognitive ability in non-human animals, enabling chimpanzees to modify their foraging strategies based on prior success.

Sensory Skills: Sight, Smell, Taste, and Touch

Chimpanzees were observed using all four primary senses to inspect nests. They visually examined, sniffed, tasted, and touched the nests to detect ant presence. This multisensory approach underscores their adaptability and problem-solving capabilities in an environment where resources are scarce.

Implications for Conservation and Human Evolution

The research provides critical insights into chimpanzee cognition and its evolutionary significance.

“Studying chimpanzee cognition in ecologically relevant contexts helps us understand the evolution of human cognitive capacities,” says Professor R. Adriana Hernandez-Aguilar.

Chimpanzees in Dindefelo inhabit a savannah-like environment—hot, dry, and open—similar to the landscapes where early hominins evolved. Understanding how chimpanzees solve foraging challenges in such settings sheds light on the survival strategies of our ancient ancestors.

Moreover, the study emphasizes the importance of conserving these endangered primates. By uncovering their dietary habits and ecological strategies, researchers hope to bolster efforts to protect them in their natural habitats.

“Chimpanzees are an endangered species, and learning more about the strategies they use to obtain important foods in the wild helps us to conserve them,” the authors conclude.

A Window into Evolutionary Intelligence

This research not only highlights the remarkable cognitive abilities of chimpanzees but also bridges the gap between primate behavior and human evolution. By understanding how our closest relatives adapt and thrive in challenging environments, we gain a deeper appreciation of the evolutionary roots of our own intelligence.

Related Research Studies

These studies collectively provide insights into the cognitive, ecological, and cultural aspects of chimpanzee foraging and tool use, emphasizing their interactions with concealed resources like army ants.

• Chimpanzees of the Taï Forest: Social Strategies in a Complex Environment

  • Author: Boesch, C.

  • Publisher: Cambridge University Press, 1996.

  • DOI: 10.1017/CBO9780511752414

  • Summary: Discusses foraging behaviors, including army ant predation, emphasizing spatial memory and cognitive strategies in chimpanzees.

• Mental Map in Wild Chimpanzees: An Analysis of Hammer Transport for Nut Cracking

  • Authors: Normand, E., Boesch, C.

  • Journal: Animal Behaviour, 2009.

  • DOI: 10.1016/j.anbehav.2009.01.008

  • Summary: Explores how chimpanzees use mental maps to remember and transport tools over long distances for nut cracking.

• Cultural Variation in Chimpanzee Tool Use

  • Authors: Whiten, A., Goodall, J., McGrew, W. C., Nishida, T., Reynolds, V., Sugiyama, Y., & Boesch, C.

  • Journal: Nature, 1999.

  • DOI: 10.1038/21415

  • Summary: Reviews tool-use variations in chimpanzee populations, with examples of foraging for ants and termites.

• Ant Dipping in Wild Chimpanzees: Tool-Use to Exploit a Variable Resource

  • Authors: McGrew, W. C.

  • Journal: Journal of Human Evolution, 1974.

  • DOI: 10.1016/0047-2484(74)90009-X

  • Summary: Focuses on how chimpanzees utilize tools to extract ants, analyzing efficiency and cognitive understanding of resource availability.

• Cognitive and Physical Constraints on Chimpanzee Tool-Use

  • Authors: Sanz, C., Morgan, D.

  • Journal: Current Biology, 2007.

  • DOI: 10.1016/j.cub.2007.02.037

  • Summary: Examines the decision-making processes behind chimpanzees' tool-use strategies, emphasizing underground food sources.

• Long-Term Memory in Chimpanzees: Implications for Ecology and Behavior

  • Authors: Janmaat, K., Ban, S. D., & Boesch, C.

  • Journal: Current Biology, 2013.

  • DOI: 10.1016/j.cub.2013.08.017

  • Summary: Studies long-term memory in chimpanzees concerning fruiting trees and applies findings to broader ecological contexts.

• The Adaptive Value of Army Ant Predation for Wild Chimpanzees

  • Authors: Schöning, C., Humle, T., Möbius, Y., & McGrew, W. C.

  • Journal: PLoS ONE, 2008.

  • DOI: 10.1371/journal.pone.0003294

  • Summary: Investigates the energetic benefits and challenges of army ant predation for chimpanzees.

• Memory of Nest Locations by Chimpanzees: Implications for Early Hominins

  • Authors: Matsuzawa, T., Humle, T.

  • Journal: Primates, 2009.

  • DOI: 10.1007/s10329-009-0157-8

  • Summary: Explores how chimpanzees remember and revisit specific resource sites, linking findings to early hominin foraging behaviors.

• Seasonal Resource Categorization and Behavioral Adaptation Among Chimpanzees

  • Authors: Clark, J., Linares-Matás, G.

  • Repository: University of Cambridge, 2023.

  • Link: PDF Access

  • Summary: Discusses how chimpanzees categorize and adapt to seasonal resource changes, focusing on underground food sources.

• Behavioral Ecology of Army Ant Predation in Gombe Chimpanzees

  • Authors: Goodall, J.

  • Journal: Journal of Human Evolution, 1986.

  • DOI: 10.1016/0047-2484(86)90007-6

  • Summary: Classic study examining the behavioral and ecological contexts of army ant predation.