Are Memories just for Humans?

New research suggests that chimps have an episodic memory for tasks they did three years ago.
16 July 2013


Hannah - So, I've got a paper that's been published this month, all about episodic memory. So, my first episodic memory was, when I was 3, my big sister shoved a Young Male Chimpdried pea at my nose, so mum and dad had to race me to a hospital. I think I'm clearly remembering sitting in the doctor's chair and having this scalpel, this tool being used to try and tweak this dried pea out of my nose.

Chris - Did it make it into your brain?

Hannah - It didn't make it into my brain, but it was pretty far up. So, since this first early memory of mine, I have associated tweezers and scalpels and peas, and surgery, and healing people, and I've also had a great fondness for mushy peas. So, this is apparently something called 'episodic memory'. So, where, when and why, and it's always been thought previously that it's only humans that can exhibit such longer term episodic memory. So, scientists publishing in the journal of Currently Biology has a published a quite long term study, looking at over 3 years, how chimpanzees and orang-utans can remember distant past events.

Chris - I bet they didn't put peas up their noses though.

Hannah - They didn't push peas at their noses, no. Instead what they did was they took the orang-utans and the chimpanzees and they put them in kind of almost like a first floor flat with different rooms in it and they went and hid different boxes that contained different tools, and tempting them on a shelf, very high up was their favourite kind of food - a nice banana. The chimpanzees and the orang-utans couldn't reach this banana unless they got the tool from a hidden box within one of these rooms in the flat and then use that as a reach in order to yank down the banana. So, the researcher took the primates into the room and showed them the boxes once. They remembered which box they had to open in order to get the right tool, in order to yank down the banana, in order to get their reward. And then the researcher, 3 years later, took them back into the room. They had actually been in this room since, but not with this particular task and within 5 seconds, the primates quickly found the right box and did the same trick and got their banana, and went, "Yum, yum, yum! That's nice."

Chris - These are quite long-lived creatures, aren't they? And we have good lifelong memories. If it is their favourite treat, it would've made a big impression on them, being able to retrieve it, so I'm not actually that surprised that they would remember that.

Hannah - Yes. Scientists have long thought that this type of long term episodic memory is what makes us humans unique, but there's a lot of evidence that now seems to be flooding in that's forcing scientists to re-evaluate this. So for example, Nicola Clayton who works here at Cambridge at the Department of Psychology has been working with the scrub jay. So, a type of corvid, a bird and she's found that over a period of days, they can do similar tasks as well. She hasn't looked at longer periods, but it seems as though other types of species do have this longish term episodic memory as well. So, it's really quashing some scientist view of what it is to be human.

Chris - Oh dear! But not too much, "Oh dear!" We're all one big happy animal family. You can find out more information including the references to the papers that Hannah and I have been discussing on our website that's at


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