Via Taslima – a study shows that chimps and orangs can have episodic memories after three years.
It has been well established in humans that sensory cues like songs and smells can help transport our minds back to the past.
The team, led by Gema Martin-Ordas of Aarhus University, Denmark, used the same principle. They found that cues – keeping the experimental set up the same – triggered the apes’ memories.
They observed that 90% of the apes who experienced the event three years earlier found the tool in the correct location almost instantly.
“Our data, and other emerging evidence, keep challenging the idea of non-human animals being stuck in time,” said Dr Martin-Ordas.
“We show not only that chimpanzees and orangutans remember events that happened two weeks or three years ago, but also that they can remember them even when they are not expecting to have to recall those events at a later time.
“What this shows is that the episodic memory system in humans is not as unique as we thought it was, as we share features with non-human primates.”
In 2009, the team ushered 12 of the apes into the middle of several connected cages. In full view, they hid two tools in different boxes within the adjacent rooms. Their job was to remember where these tools were—they would need them to reach an inaccessible piece of food in a later test. They had four shots at doing this.
Over the next three years, the apes went about their lives. They ate, slept, socialised, and took part in many more studies. Then, in 2012, eleven of them were led into the same set of rooms with tool-containing boxes in the same locations. And all of them, except for one, went straight to boxes and retrieved the tools. They remembered.
Call was surprised at “how quickly they retrieved the tools as soon as we opened the doors”. They all did this on their first attempt, without prompts or trial-and-error. They didn’t know this test was coming—in 2009, even the researchers hadn’t planned to repeat their experiment three years later. And by contrast, seven individuals that weren’t part of the original experiment didn’t head for the boxes; they just explored the rooms randomly.
Three years. That’s impressive.