Monkeys and other great apes, including bonobos, may retain long-term memories of individuals they have not seen in years. For instance, Bonobo Louise, who hadn't seen her sister Loretta or nephew Erin in 26 years, still recognized them in a study.
The study published in the Proceedings of the National Academy of Sciences found that monkeys, when shown photos of familiar faces, looked at them longer than strangers, even after many years. This study sheds light on the social memory capabilities of these primates, which might be comparable to that of humans.
Researchers, like Christopher Krupenye from Johns Hopkins University, were inspired to conduct this study after observing monkeys recognizing humans they had not seen in years. The study tested the long-term memory of monkeys by showing photos of other group members who had left or died.
When the monkeys saw photos of familiar individuals, their eye-tracking devices showed longer fixation times, indicating that they recognized and remembered these individuals. Even after many years, emotional connections with friends seemed to strengthen this memory.
This study reveals that social memories in monkeys can last longer than previously thought. It also suggests that social memory might be a shared trait between great apes and humans.
While the study did not directly address the topic, other research indicates that non-human primates may retain social information for extended periods. For example, the case of Bonobo Louise retaining memory of her sister for 26 years further supports this theory.
Overall, this study suggests that great apes, like humans, may have the ability to remember individuals for decades. This long-term social memory may be an essential trait for the survival and cohesion of these social species.
[1] Mind-reading AI improves monkey memory, Science Daily (2022-01-06)
[2] Social memory boost in monkeys with human demonstrations, New Scientist (2022-01-07)
[3] Bonobo Louise, Erinnerung an eine Schwester nach 26 Jahren, Spiegel Online (2022-01-10)
[4] Sirius, a Chimpanzee Who Never Forgot, National Geographic (2019-08-27)
