Chimps, Orangutans Able to Remember Small Details Years Later

Chimpanzees and orangutans appear to have the ability to remember the distant pass, according to a study published in Current Biology.

Both primate species exhibited the clear ability to recollect where objects were hidden in a tool-finding event they had experienced just four times three years earlier and a singular event from two weeks before, the researchers found.

"Our data and other emerging evidence keep challenging the idea of non-human animals being stuck in time," Gema Martin-Ordas of Aarhus University in Denmark said in a press release. "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."

Nor does it stop there.

Remarkably, the chimpanzees and orangutans in the study were also able to distinguish between similar past events in which the same tasks, locations and people were involved, according to the study.

"This is a crucial finding since it implies that our subjects were able to bind the different elements of very similar events -- including task, tool, experimenter," Martin-Ordas said. "This idea of 'binding' has been considered to be a crucial component of autobiographical memories."

When presented with a particular setup, chimpanzees and orangutans instantaneously remembered where to search for tools and the location of a tool they had seen only once. In particular, the researchers note the complexity and speed of the primates' recall ability.

"I was surprised to find out not only that they remembered the event that took place three years ago, but also that they did it so fast!" she said.

On average, the researchers found that it only took five seconds to find the hidden tools.

"Again, this is very telling because it shows that they were not just walking around the rooms and suddenly saw the boxes and searched for the tools inside them. More probably, it was the recalled event that enabled them to find the tools directly."

Ultimately, she explained, the new findings are just the beginning of a completely new line of research on memories for past events in animals other than humans.