Chimps, Orangutans Have Human-Like Memory

Forgot your Facebook password? Can’t remember if it’s one cup of sugar or two? Misplaced your keys—again? 

Why we remember and forget is a big topic of study, and scientists at the Aarhus University Center on Autobiographical Memory Research in Denmark have turned to the animal kingdom for answers.

Now, a new study published today in Current Biology shows that captive chimpanzees and orangutans can quickly recall past events like people. Chimpanzees are our closest relatives.

chimpanzee picture
A chimpanzee named Frodo seems to pose in Gombe Stream National Park, Tanzania.

“I think [the study] tells us that our memory systems are not unique,” said study co-author Gema Martin-Ordas, a postdoctoral researcher.  (Read more about memory in National Geographic magazine.)

“We’re showing that there are some features we share with other animals.”

“Shocking” Primate Memory 

Martin-Ordas and her team used specific cues to trigger memories of an experiment that the chimps and orangutans had learned three years prior.

During that previous experiment, researchers hid tools in strategically placed boxes and asked the primates to find them. When the scientists recreated the test, the primates had no trouble quickly remembering where the tools had been concealed.

This suggests that primates can quickly recollect past events, a feat that scientists previously thought only humans could do.

“I was shocked that the chimpanzees and orangutans found the tools,” Martin-Ordas said. “I was skeptical. I thought it wouldn’t work, and it did.”

“This is really impressive,” she added.

Memories Not Created Equal

If you have trouble remembering what you had for breakfast yesterday—let alone three years ago—don’t worry: Not all memories are created equal.

People remember general and specific events. General events are those that happen over and over, similar to our collective memory of attending school. Specific events are those that happen once, like our first day of school.

There are lots of triggers for memories. Martin-Ordas and colleagues used visual cues with the primates, using the same lab layout and technology to activate the animals’ remembrance of the experiment.

Other triggers like sound and smell can also prompt powerful memories.

“Every time I smell this perfume, it brings back memories of me going to school when I was five or six,” Martin-Ordas said. “It’s really intense.” (Test your memory with a National Geographic game.) 

Memory recall is important for humans because it allows us to plan for future events, she added. When we’re thinking about what we’re going to pack for our next trip, for example, we usually have in mind what happened during the last one.

Memories also allow people to build their sense of self across time in a coherent way, which plays a big role in our personal wellbeing.

“We usually share memories with others,” Martin-Ordas said. “That’s important to establish relationships.”

Memory Research Still Ongoing

Next, researchers will look at whether chimpanzees and orangutans are aware that they’re recalling a personal memory.

Autobiographical memories are like movies that you store in your brain: When something triggers a memory, the movie replays in your head. You know that it’s your memory, but do animals have the same realization?

Chimps and orangutans “share some features of autobiographical memories that humans have, but we can’t be sure whether they’re aware of those memories, and that’s the debate,” Martin-Ordas said.

The science of memory storage and remembrance is still a field in its infancy: The brain is such a complex organ that it’s difficult to pinpoint exact memory-storage processes. (See a 3-D memory interactive.)

But further study of memory in the animal kingdom could provide valuable information that could someday prevent memory problems in people.

Tell us: What do you usually forget?

Mollie Bloudoff-Indelicato is a science journalist who loves em dashes, ’80s music and parasites. She has a master’s degree from the Columbia University Graduate School of Journalism with concentrations in science journalism, photography, and radio reporting. Contact her at news@mbloudoff.com, and follow her on Twitter at @mbloudoff.

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