I studien ”Raising the Level: Orangutans Use Water as a Tool” (från Biology Letters) klargörs att orangutanger är duktiga på problemlösning:

We investigated the use of water as a tool by presenting five orangutans (Pongo abelii) with an out-of-reach peanut floating inside a vertical transparent tube. All orangutans collected water from a drinker and spat it inside the tube to get access to the peanut.

Mer förvånande är kanske att vissa fåglar också har en dylik förmåga, enligt två nya studier:

• ”Rooks Use Stones to Raise the Water Level to Reach a Floating Worm” (från Current Biology): ”Here, we present evidence that captive rooks are also able to solve a complex problem by using tools. We presented four captive rooks with a problem analogous to Aesop’s fable: raising the level of water so that a floating worm moved into reach. All four subjects solved the problem with an appreciation of precisely how many stones were needed.”
• ”Cognitive Processes Associated with Sequential Tool Use in New Caledonian Crows” (från PLoS ONE): ”Our experiments provide the first demonstration, to our knowledge, that a non-human animal can spontaneously use up to three tools in a sequence to retrieve food.”

Never underestimate the intelligence of birds.