It was claimed that the ability to recall personal past events is uniquely human; but great apes can remember specific events for long periods of time (months to years); the forgetting curve is similar to ours

Long-Term Memory of Past Events in Great Apes. Amy Lewis, Dorthe Berntsen, Josep Call. Current Directions in Psychological Science, January 2, 2019. https://doi.org/10.1177/0963721418812781

Abstract: It has been claimed that the ability to recall personal past events is uniquely human. We review recent evidence that great apes can remember specific events for long periods of time, spanning months and even years, and that such memories can be enhanced by distinctiveness (irrespective of reinforcement) and follow a forgetting curve similar to that in humans. Moreover, recall is enhanced when apes are presented with features that are diagnostic of the event, consistent with notions of encoding specificity and cue overload in human memory. These findings are also consistent with the involuntary retrieval of past events in humans, a mode of remembering that is thought to be less cognitively demanding than voluntary retrieval. Taken together, these findings reveal further similarities between the way humans and animals remember past events and open new avenues of research on long-term memory in nonhuman animals.

Keywords: great apes, long-term memory, spontaneous retrieval, episodic memory, event memory