Untrained orangutans instinctively use tools

By Joe Morgan via SWNS

Untrained orangutans instinctively use hammers to strike and sharp stones to cut, reveals a new study.

The largest tree-living great apes engage in behavior that shows how close humans are to our genetic cousins, according to researchers.

Without prompt, orangutans can strike rocks together, break off sharp pieces and use those flints to cut.

The remarkable behavior of tool-making was tested on two captive male orangutans in Kristiansand Zoo in Norway.

Neither had previously been trained or exposed to any demonstrations.

Each orangutan was provided with a concrete hammer, a prepared stone core, and two baited puzzle boxes requiring them to cut through a rope or a silicon skin in order to access a food reward.

Both orangutans spontaneously hit the hammer against the walls and floor of their enclosure, but neither directed strikes towards the stone core.

In a second experiment, the orangutans were also given a human-made sharp flint flake, which one orangutan used to cut the silicon skin, solving the puzzle.

This is the first demonstration of cutting behavior in untrained orangutans, according to the study.

Researchers then decided to see if showing the desired behavior would result in a quicker demonstration.

The team demonstrated how to strike a core to create a flint flake to three female orangutans at Twycross Zoo in the UK, and after one time a female went on to use the hammer to hit the core directing the blows towards the edge.

Dr. Albes Motes-Rodrigo, of the University of Tübingen, Germany, said: "Observations suggest that two major prerequisites for the emergence of stone tool use – striking with stone hammers and recognizing sharp stones as cutting tools – may have existed in our last common ancestor with orangutans, 13 million years ago.

“Our study is the first to report that untrained orangutans can spontaneously use sharp stones as cutting tools.

"We also found that they readily engage in lithic percussion and that this activity occasionally leads to the detachment of sharp stone pieces.”

The study was published in the journal PLOS One.