Orangutans are bright enough to use water as a tool, a finding that researchers say is straight out of Aesop's Fables.

Five orangutans at the Leipzig Zoo in Germany were each shown shelled peanuts. The nuts floated out of reach inside a clear 10-inch-high plastic tube quarter-filled with water.

All of the orangutans collected water from a drinker and spat it inside the tube to float the peanuts high enough to grab them, averaging three mouthfuls before success. In their first attempts, the apes on average took nine minutes before they got the nuts, but they only needed just 31 seconds by their tenth try.

The researchers had to make sure the tube was strong, "because the jaw power of orangutans is enormous," recalled Natacha Mendes, a biologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig. "After so much work constructing tubes, it can be heartbreaking to see it getting destroyed so easily."

The findings reminded Mendes of the fable of the thirsty crow, which threw stones into a pitcher to raise and drink the otherwise unreachable water. And the research sheds light on the nature of intelligence among humanity's closest relatives, the great apes, she said.

"This is intriguing because it shows they solved problems that go beyond their immediate experience," said Harvard biologist Marc Hauser. In the wild, orangutans are tree-dwellers that don't live near bodies of water, he explained. "It would be interesting to see how flexible they really are, how far they can go beyond what they've evolved to solve."

The research was detailed online July 3 in the journal Biology Letters.

  • Video: Watch the Clever Orangutans
  • Escaped Orangutan Goes Ape
  • Amazing Animal Abilities