Scientists Discover Recursion in Crows, a Cognitive Process Thought to Be Exclusive to Humans and Other Primates

According to scientists, Crows can use recursion, a cognitive skill thought to be exclusive to humans and other primates.

A recent study founds that crows have the cognitive capacity to understand one of the linguistic components that make human language so tricky.

According to Noam Chomsky and other linguists in the early 2000s, Recursion set the human language apart from that of animals. It was the only feature that belonged solely to human language. This is not the case, as it turns out; a study from 2020 demonstrated that rhesus monkeys could perform the task as well, and a recently released study demonstrates that crows can perform recursion.

What is recursion, then? It is the ability to identify paired elements in longer sequences, which has been cited as one of the essential components of human symbolic competence. Take the following instance: The rat that the cat chased fled. Adult humans can easily understand that the rat ran and the cat chased, despite the term being slightly ambiguous. Recursion is the coupling of the words “rat” and “run” and “cat” and “chased”.

Put, monkeys and crows, like humans, can identify that a structure may contain other structures that have meaning. However, for many years, scientists believed that recursion was only understood by humans, or at the very least, primates. However, after it was found about two years ago that rhesus monkeys can comprehend the concept of recursion on par with three to four-year-old human children (albeit with some additional training), a team has now carried out similar experiments with crows, and they turned out to outperform monkeys in some aspects!

Using the same approach as their colleagues in the earlier Wisconsin work with monkeys, University of Tübingen researchers analyzed birds. In this one, the animals had to locate a pair of symbols within a string of symbols. Thus, they had to figure out, for instance, where the pair of brackets were situated within the symbol sequence ()>.

When they did, the researchers started making longer sentences to determine if the test subjects could still tell the embedded sentences apart.

Without the additional instruction the rhesus monkeys received, the individuals could recognize the embedded characters in 40% of trials.

In other words, it turns out that recursive capabilities are not exclusive to primate genealogy. Which serves to emphasize once more how intelligent crows are.