Birds, apes can plan ahead, studies show

Experiments on orangutans and scrub jays suggest humans aren't the only animals who can think ahead, scientists say.

Orangutans and bonobos-small apes closely related to chimpanzees - have shown that they can remember which tools they need to retrieve a treat.

And scrub jays have shown that they will hide their food a second time if a rival bird saw them store it the first time.

"Planning for future needs is not uniquely human," Thomas Suddendorf of the University of Queensland in Australia wrote in a commentary accompanying the two studies, published Friday in the journal Science.

Carefully planned experiments

Many animals such as squirrels hide their food, and some, such as chimpanzees and crows, have been shown to use tools to retrieve food, but the two carefully planned experiments show that animals can plan for the future, as well.

In one study, Nicholas Mulcahy and Josep Call of the Max Planck Institute for Evolutionary Anthropology in Germany tested orangutans and bonobos at the zoo in Leipzig.

They set up a series of experiments that required the apes to remember a complex method for retrieving a treat using tools the researchers provided.

In one experiment, they inserted a piece of uncooked spaghetti into a metal cylinder and hung bunches of grapes from the ends of the spaghetti.

"To obtain the reward subjects had to break the spaghetti by inserting a plastic tube through the top hole over the cylinder. That caused the grapes to fall down and hang in front of the bottom holes thus allowing subjects access to them," the researchers wrote.

In another experiment, the apes had to use a metal hook to retrieve a bottle of grape juice. To pass the test, the subjects had to pick which tool was needed to get the juice and remember to bring it back with them some time later.

Passed tests

Both orangutans and bonobos passed the tests several times, the scientists said.

In the other set of studies, Joanna Dally of the University of Cambridge in the U.K. and colleagues studied the food-hiding behaviour ofcaptive scrub jays. The birds are members of the corvid family, which includes jays, crows and ravens, and considered the smartest group of birds.

They found that if a bird dominant to the jays saw them store their food, the jays would come back later and move the food when the dominant bird wasn't there.

However, if the bird that watched the food being hidden was a subordinate or a mate, the jay didn't move their food cache. The researchers said the birds could fight off a subordinate bird that tried to steal the food.

"These results suggest scrub jays remember who observed them make specific caches," Dally's research team wrote.

The ape researchers said the two studies show that not only humans can plan for future needs.

"Together with recent evidence from scrub jays, our results suggest that future planning is not a uniquely human ability, thus contradicting the notion that it emerged in hominids only with the past 2.5 to 1.6 million years,"wrote Mulcahy and Call.