Episodic memory and mental time travel have been considered uniquely human traits. This view has begun to change with the development of behavioral criteria to assess what is called episodic memory in animals. Key findings range from evidence of “what, where, when” memory in jays, mice and bees to episodic memory and future-oriented behavior in wild, free-foraging animals. In a new study, scientists investigated episodic memory and future-oriented behavior in wild, free-foraging animals. Egyptian fruit bat (Rusetus aegyptiacus)The team found that fruit bats rely on mental time maps to display future-oriented behaviour when foraging, and that time-mapping ability requires experience and is lacking in inexperienced bats.
Egyptian fruit bat (Rusetus aegyptiacus) track tree phenology and estimate fruit availability since their previous visit. Bats exhibit future-oriented behavior, flying to trees rich in specific proteins, while flying past many familiar sugar-rich trees. Young bats must learn tree phenology through experience. Image courtesy of Harten others., doi:10.1016/j.cub.2024.05.046.
“For many years, the cognitive abilities to recall and plan personal experiences (episodic memory) have been thought to be uniquely human,” Tel Aviv University.
“However, a growing body of research suggests that various animals also have such abilities, although nearly all of these studies have been carried out in laboratory settings, as field studies on this issue are difficult to conduct.”
“To test these capabilities in wildlife, we designed a unique experiment using a wild colony of flying foxes.”
The researchers surmised that bats that depend on fruit trees for survival need to develop the ability to track food availability both spatially (where are the fruit trees?) and temporally (when does each tree bear fruit?).
As you navigate a landscape with numerous fruit and nectar trees, you'll need to mentally keep track of resources in order to revisit them at the right time.
To test this hypothesis, they fitted each bat with a small, high-resolution GPS tracker, allowing them to record their flight routes and the trees they visited over several months.
The vast amount of data collected in this way was thoroughly analyzed, yielding surprising results.
“Our first research question was: do bats form mental maps of time?” says Dr Lee Harten from Tel Aviv University.
“To investigate this issue, we confined bats to their colonies for various periods of time, ranging from one day to a week.”
“We wanted to see if the bats would recognise that time had passed and behave accordingly.”
“We found that after one day in captivity, the bats would return to the trees they had visited the previous night. But after a full week, the older bats, based on their past experience, began to avoid trees that had stopped bearing fruit in the meantime.”
“In other words, they could estimate how much time had passed since they last visited each tree, and thus know which trees only bore fruit for a short time and were no longer worth visiting.”
“Younger, inexperienced bats were unable to do this, suggesting that this is an acquired skill that must be mastered.”
“The first research question was about past experience, but the second question was about the future. Do bats exhibit future-oriented behavior? Can they plan for the future?”
“To address this issue, the researchers observed the route each bat took to reach the first tree in the evening, which could indicate a plan made before leaving the colony.”
“We found that bats usually fly directly to specific trees they know, sometimes up to 20-30 minutes away,” said Dr Chen Xin from Tel Aviv University.
“They're hungry, so they fly faster the further away the trees are, which suggests they're planning where they're going.”
“Furthermore, because they are so focused on their chosen target, they pass by other trees and even good sources of information that they only visited yesterday, demonstrating their ability to postpone gratification.”
“We also found that the first bats to leave the colony chose trees with fruits high in sugar, while those who left later sought out fruits with protein.”
The findings suggest that bats plan their foraging before they leave the colony, knowing exactly where they'll be flying and what nutrients they'll be looking for.
“The gap between human and animal cognition is one of the most fascinating questions in science,” Professor Yobel said.
“Our study demonstrates that flying foxes are able to carry out highly complex decision-making processes involving three questions that demonstrate cognitive capabilities: 'where?' (the location of each tree), 'when?' (when the trees will bear fruit) and 'what?' (what nutrients the trees provide, sugars or proteins).”
“Once again, the gap wasn't clearly carved out, and we find that humans are not as special as some think.”
“Apparently, humans and animals all lie on a spectrum, and almost all human abilities can also be found in animals.”
a paper The findings were published in the journal. Current Biology.
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Lee Harten othersTime mapping and future-oriented behavior in free-ranging wild fruit bats. Current BiologyPublished online June 20, 2024; doi: 10.1016/j.cub.2024.05.046
This article is a version of a Tel Aviv University press release.
