Challenges not found in nature strengthen case that certain birds evolved some apelike thinking
M. Osvath/Lund University
Ravens have passed what may be their toughest tests yet of powers that, at least on a good day, let people and other apes plan ahead.
Lab-dwelling common ravens (Corvus corax) in Sweden at least matched the performance of nonhuman apes and young children in peculiar tests of advanced planning ability. The birds faced such challenges as selecting a rock useless at the moment but likely to be useful for working a puzzle box and getting food later.
Ravens also reached apelike levels of self-control, picking a tool instead of a ho-hum treat when the tool would eventually allow them to get a fabulous bit of kibble 17 hours later, Mathias Osvath and Can Kabadayi of Lund University in Sweden report in the July 14 Science.
“The insight we get from the experiment is that [ravens] can plan for the future outside behaviors observed in the wild,” Markus Böckle, of the University of Cambridge, said in an e-mail. Böckle, who has studied ravens, coauthored a commentary in the same issue of Science.
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RAVENS ROCK A raven gets a snack out of a box by dropping in a rock that tilts a shelf inside and lets food tumble out at the bottom. Tests of selecting and saving the rock used in this task suggest the birds have some capacity to think ahead. C. Kabadayi, M. Osvath
In the wild, ravens cache some of their food, but that apparent foresight could be more of a specific adaptation that evolved with diet instead of as some broader power of planning. The Lund tests, based on experiments with apes, tried to challenge ravens in less natural ways. The researchers say the birds aren’t considered much of a tool-using species in nature, nor do they trade for food.
“The study for the first time in any animal shows that future planning can be used in behaviors it was not originally selected for” in evolution, Böckle says.
Some of the abilities required for the tests aren’t completely out of the realm of what ravens do in nature, says Valérie Dufour at the French national research institute CNRS in Strasbourg. "Food-caching birds are naturally inclined to keep track of what they cache and where," she says. "Still, their flexibility in adapting these skills to other contexts is remarkable."
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