This is all the more impressive because ravens are not frequent tool-users, and they’ve never been known to barter for food in the wild. Unlike Clayton’s jay studies, Osvath’s experiments forced the birds to do things that they don’t naturally do. Their success suggests that they can plan for the future in the same flexible way that humans and other great apes can.
Again, not all researchers are convinced. If the ravens don’t actually know when they’ll encounter the puzzle box, wonders Jennifer Vonk from Oakland University, who also studies corvids, how do they know which item to select? Since they were trained to use the stone to open the box, and since the stone was the only object that ever did so, “it makes sense that the birds would develop a preference for that tool,” Vonk adds. “It isn’t clear that this preferential selection reflects future planning.”
Osvath argues that the birds were only given minimal training, in a different location than where they were tested. “These animals had only used a tool five times in their entire life, and they aren’t predisposed to tool use,” he says. And when tested, all the birds picked the right object on their very first go, suggesting that they didn’t just learn the correct answer over the course of the experiment.
Even if you don’t buy any of that, he says, you would still need to explain why monkeys consistently fail at these kinds of tasks, or why human children only succeed after they turn 4. “They’re really good at learning and have predispositions for tool use,” says Osvath, and yet they don’t pick the right tool or token when tested in the same way as the ravens.
“This study contributes to lots of mounting evidence for the amazing [parallel evolution] between apes and corvids,” says Laurie Santos from Yale University. They are separated by 320 million years of evolution, but “in terms of their tool-use, elaborate social cognition, and now even forward planning, these two groups are surprisingly similar, which raises some cool questions about why the two groups wound up so similar.”
To plan for the future in a flexible way, animals must be able to learn, represent a future event in their minds, understand that their current actions can contribute to an abstract and unobservable goal, and restrain the pull of their present senses to focus on that goal. Do corvids have all of these skills? Santos isn’t sure. “The current results show that birds value objects that they know might be valuable later. It’s nice evidence for forward planning, but I don’t think it shows that the birds are thinking of themselves in the future in any rich way,” she says.
To the extent that corvids and apes share similar skills, did they evolve their abilities independently? Or did they build upon abilities that were present in their common ancestors? “Those are questions I’ll work on for the rest of my life,” says Osvath.