Ravens and great apes have not shared a common ancestor for over 300 million years, so what explains it? Evolution is not a straight line and the authors speculate that the cognitive "planning" abilities they share in common re-appeared, on a separate evolutionary path, in the birds.
Some corvids, a family of birds that includes ravens, cache food, which is an ability to plan beyond the current moment. In a new paper, Can Kabadayi and colleagues sought to explore the ability of ravens to plan ahead using a series of experiments.
First, ravens were trained to use a tool to open a puzzle box in order to access a reward. The ravens were then presented with the box, but not the tool. The box was removed and one hour later the ravens were given the opening tool, as well as several "distractors."
Nearly every raven chose the correct, apparatus-opening tool; upon being presented with the box 15 minutes later, they used the tool to open it, with a success rate of 86%. A high success rate (78%) was also seen in similar experiments where ravens used a token to later barter for a reward.
Credit: Can Kabadayi and Mathias Osvath
The ravens planned for bartering more accurately than apes, the researchers report, and they were on par with them in the tool-using tasks, despite lacking predispositions for tool handling. Next, the ravens were presented with the correct, apparatus-opening tool, distractor tools, and an immediate reward, but were only permitted to select one item.
The immediate reward was less appealing than the reward in the box, the researchers report, demonstrating a level of self-control in the birds similar to that seen in apes.