Crows Perform Yet Another Skill Once Thought Distinctively Human

The crow is one of the smartest animals in the world. They have the ability to make rule-guided decisions and to create and use tools. They seem to have a sense of what number is. Birds are able to understand the process of embedded structures in other structures, which was thought to be a unique human ability.

Language has a key feature called recursion. It allows us to build complex sentences. The mouse the cat chased fled. The clause "the cat chased" is included in the clause "the mouse ran." Recurring was thought to be a trait of humans on its own. Humans have a key feature that distinguishes them from other forms of communication with animals. Questions about that assumption were still being asked. Diana Liao is a researcher at the lab of a professor at the University of Tbingen in Germany.

In a study of monkeys and human adults and children published in 2020, a group of researchers reported that the ability to produce sequence is not unique to our species. Humans and monkeys were shown a display with two brackets that appeared in different places. The subjects were trained to touch them in the order of a "center- embedded" sequence. monkeys were given a small amount of food or juice as a reward after receiving verbal feedback from humans. After presenting their subjects with a completely new set of brackets, the researchers looked at how often they rearranged them in a way that made sense. Two of the three monkeys in the experiment were more likely to generate a repetitive sequence than a nonrecursive one. Around half of the trials were generated by one animal. Forty percent of the trials had three- to four-year-old children forming sequence.

The paper prompted Liao and her colleagues to look into whether crows have the ability to repeat themselves. The team adapted the protocol used in the 2020 paper to train crows topeck pairs of brackets. The birds were tested on a new set of symbols to see if they were capable of generating such sequence on their own. The crows did well with children. The monkeys required more training than the birds did, but the birds were able to produce 40 percent of the trials. The results were published in a journal.

Giorgio Vallortigara, a professor of neuroscience at the University of Trento in Italy, was not involved in the work. He says that they don't seem to have anything similar to human language. It is possible that animals use recursion to represent their relationships.

Some experts were unconvinced that the monkeys understood the study's findings. The animals learned the order in which the brackets were displayed. When the monkeys were shown a different pair, such as ( ) and , they would pick the one they had never seen before. They learned at the end of the sequence that the matching brackets would come at the end.

The sequence from two pairs to three pairs was extended by Liao and her colleagues. The likelihood of producing the sequence without grasping the underlying concept of recursion decreases with three pairs of symbols. The researchers found that the birds preferred center- embedded responses.

Scientists are still skeptical. A senior researcher in psychology at the French National Center for Scientific Research says that the findings can still be seen from a simple associative learning standpoint. The researchers put a border around the closed brackets in their sets in order to help the animals define the order of the brackets. The same bordered layout was used in both studies. The limitation of the study is that the animals could have grasped that bordered symbols, which would always end up toward the end of a sequence, and thus aided them in learning the order in which open and closed brackets were displayed.

Rey thinks that the idea of recursive processing is flawed. There have been no satisfactory explanations of how the ability to recognize and manipulate such sequence can be explained in humans. One camp believes that human language is built on unique capacities such as the ability to understand recursion and the other believes that it emerged from simpler processes such as associative learning.

Even though the borders helped, the crows still had to figure out where the open and closed brackets were located. If the birds only learned that open brackets were at the beginning of the sequence and closed brackets were at the end, there would be an equal proportion of correct and incorrect responses.

Seeing that birds whose ancestors long ago diverged from those of primates on the branching evolutionary tree of life suggests that this capacity is evolutionary ancient or that it developed independently as a result of what is known as converge. The latter brain architecture may not be necessary for displaying this cognitive ability because birds' brain lacks the layers of the primate's.

The findings of the new paper fit into a long line of studies showing that birds have the same cognitive skills as humans. Osvath says that the data shows that birds have been completely misunderstood. It's simply incorrect to say that mammals took over the world.