In the study, scientists at Sweden's Lund University gave five ravens a series of puzzles, first teaching the birds how to get a food treat out of the puzzle box with a specific tool, and then inviting the ravens to interact with the puzzle box with no tools and with objects that didn't work on the boxes.
In one test, ravens were trained to use a tool to open a puzzle box in order to access a reward.
"The human brain stores memories of past events to guide decision-making about current and future events", wrote psychologists Markus Boeckle and Nicola Clayton of the University of Cambridge.
The independent emergence of flexible planning might be an example of convergent evolution, a phenomenon by which an environment selects for strikingly similar adaptations among unrelated lineages.
Similarly, the ravens also proved that they are capable of self-control when researchers presented them with the choice of either an immediate reward or a tool which would allow them to gain an even bigger reward with a little more effort. Further on it was said that only humans and the great apes had been capable of planning ahead, The Independent reported.
As a result of the study it was deemed that ravens have the ability to plan ahead in life but not just when it comes to hiding and storing their food.
The ravens could also solve a similar future-planning problem that involved bartering. "Adolescent ravens live in kind of roving bands without a fixed territory where social alliances can change very quickly", he says.
The researchers note in their paper that the ravens' performance bore "conspicuous similarities" to the abilities of great apes in similar tasks. And they prepared for future bartering, too.
Still, not everyone believes the study shows that ravens are thinking into the future. Their research results became available earlier this week in the journal Science.
During the tests the birds were shown a box that had a tube sticking out the top. Other apes also seem to be able to plan for the short-term future, at least up to one night. Afterwards, they had to select the correct item, hold onto it for 15 minutes, and the trade it with one of the researchers for a reward. That was around 320 million years ago, suggesting that everything from snakes to rabbits should have the same abilities. Previous observations had already shown that members of the corvid family, which includes the raven, are intelligent birds. It's a behaviour that's previously only ever seen in humans and great apes. In April 2016, a study revealed ravens have the same level of self-control as chimpanzees despite having smaller brains.
Then, the box and the stone were removed. When presented with the box containing the kibble fifteen minutes later, the ravens passed on the smaller reward 86 percent of the time, ignoring the distractors, and picking the correct tool to open the box.
Taylor says this is the key control - divorcing the token from food association - that's missing from the study.
"What I find most interesting is that it's not just one skill that has evolved here, but a combination of skills", Osvath told ScienceAlert. They can infer when they are being watched, suggesting that they possess a theory of mind.