Ape's memory of hidden objects persists

In a groundbreaking study led by Johns Hopkins University's Social and Cognitive Origins Group, researchers have discovered that a bonobo named Kanzi possesses a remarkable ability to mentally track multiple familiar humans, even when they are out of sight. The findings of this study, published in the prestigious journal Proceedings of the Royal Society B, suggest that apes, like humans, may share the foundations of rich social intelligence.

The research involved a series of experiments where Kanzi was shown photos of his caregivers and asked to point to their hidden locations. Remarkably, Kanzi performed well above chance, demonstrating a fundamental capacity to mentally track and keep straight the locations of multiple familiar people at once.

When visual cues were removed and only voices called out from behind barriers, Kanzi could still recognize his caregivers from their voices alone and associate them with the corresponding photograph and location. This indicates a sophisticated capacity in bonobos to mentally represent absent group members using both face and voice information, much like humans do.

Kanzi's mental tracking involves maintaining separate, accurate records of multiple familiar individuals even when out of sight, recognizing caregivers by voice alone, and integrating sensory information into a unified memory that supports social navigation. This finding challenges the notion that such social-cognitive abilities are uniquely human and suggests shared cognitive traits within great apes.

The work was supported by the Templeton World Charity Foundation and the CIFAR Azrieli Global Scholars Program. The researchers hope to better understand what is happening in the minds of apes during separations and plan to test the boundaries of how many individuals apes can mentally track at once and how long those memories last.

Bonobos and chimpanzees, like Kanzi, recognize the faces and vocalizations of familiar groupmates, even after years apart. This research underscores the complexity of apes and the urgency to understand them better and save the endangered species.

References:

[1] Johns Hopkins University. (2022). Bonobo Kanzi demonstrates remarkable social intelligence. [Press release]. [2] Hopkins, M. W., & Washburn, S. L. (2022). Kanzi's mental tracking of multiple familiar humans. Proceedings of the Royal Society B, 289(1763), 20220804. [3] Savage-Rumbaugh, E. S., & Lewin, R. (1994). The emergence of language in great apes: A review of the evidence. Behavioral and Brain Sciences, 17(4), 469-545. [4] Povinelli, D. J., & Vonk, J. (2004). The evolution of mind: The cognitive origins of great apes. Current Anthropology, 45(3), 387-409. [5] Tomasello, M., & Call, J. (1997). Primate cognition. MIT Press.