Before infants learn to count using symbols (where “1” represents one thing and “2” represents twice that), they Going through stages of development This is the verbal counting stage. At this stage, when asked how many apples there are in a group of three, a toddler might respond with a prototypical counting response: “one, one, one” or “one, two, three” or “apple, apple, apple.” They understand that there are three apples, but they are not yet fully capable of representing that number in the abstract form of “three.”
Inspired by this knowledge, Diana LiaoSo the neurobiologist and postdoctoral researcher at the University of Tübingen in Germany decided to ask the obvious question: Can crows do it? Spoiler alert: Yes, crows can, the researchers say. First research Published in the journal on May 23rd ScienceCarrion crows can control their vocalizations and match the number of calls to a cue, a primitive counting system, according to a new study.
The study adds to a long list of cognitive abilities possessed by corvids (a bird family that includes ravens, magpies, and jays). The new research also aids in the quest to understand the evolutionary origins of mathematical abilities in humans. By studying the capabilities and limitations of other animals, scientists can better understand where and how human mathematical abilities originated.
“It’s really an amazing study.” Jessica Cantlon“The reality is that people are more likely to be shy than people who are not,” said a psychology professor at Carnegie Mellon University who studies quantitative reasoning and was not involved in the crow study. Popular ScienceIn humans, the connection between the vocal tract and the mathematical brain is a key part of number sense: “When you start using your voice to represent things in the world, it changes the way you think. [is the way that] “Humans acquired the ability to count during development and evolution,” she explains. “Until now, it wasn’t clear whether other animals could do it,” Cantlon adds.
Previous studies have demonstrated that crows, chimpanzees, monkeys, parrots, rats, honeybees, chickens and other animals have some quantitative reasoning ability, mainly through pecking, button pressing, food selection, screen clicking, head movements and hand singing. Distinguish Different quantities of things, implementation Basic arithmetic,Rarely, Conceptualizing ZeroBut humans’ level of vocal control is unique among animals. Even other primates “are very bad at making vocalizations that are like human language,” Cantlon says. “I think people have given up on trying to get primates to vocalize.” [vocalize] in quantitative reasoning tasks.”
Crows are just one in a long list of species that make sounds that add to the “cawing” calls of the natural world. But in contrast to humans, scientists believe that most animal calls are unconscious and instinctive, programmed at birth and elicited by external environmental cues, Liao explains. For example, a study on black-capped chickadees found that: The birds will add more. Although songbirds tend to add “dee” syllables to their alarm calls when a large predator is present, this tendency doesn’t necessarily indicate that the songbirds are literally gauging the predator’s size with their songs. Rather, the number of “dee”s may correspond to the degree of arousal caused by the predator’s presence, with larger threats being more alert. Liao wanted to explore this phenomenon in a more controlled environment, where an artificial laboratory setup could rule out the role of instinctual fear and arousal.
This new study on carrion crows is the first to clearly demonstrate that a species other than humans can link spontaneous vocalizations with an understanding of quantity. Recording crow calls “is not like counting pecks,” says Dr. Girosio VallortigaraTracking vocalizations “involves timing, and requires extensive memory and planning,” he explains. “It’s certainly an advanced cognitive skill.”
To demonstrate the corvids’ abilities, Liao and his co-authors trained three carrion crows to associate colored Arabic numerals (1, 2, 3, 4) and neutral auditory cues (sounds not related to natural threats or prey) with a flexible set of corresponding vocalizations. The process took more than a year, Liao says, and was largely trial and error. The researchers presented each crow with numbers on a screen or prerecorded sounds, and rewarded it with food if it produced the matching number of calls.
Once training was complete, the crows were tested in repeated 1-2 hour sessions. Each crow stood in front of a screen and began the test by pecking a target, which would then respond by displaying a number on the screen or playing an audio cue. The crow would respond by cawing and pecking an “enter key” on the screen to indicate the end of the response. If the cawing correctly corresponded to the number cue, the crow would receive a tasty mealworm or bird food pellet as a prize.
All three birds demonstrated that they could vocalize on cue at rates far higher than chance over 20 sessions. Most of the time, the crows responded correctly, with 100% accuracy for the number 1, over 60% for the number 2, over 50% for the number 3, and about 40% for the number 4. Using computer analysis tools, the researchers further found that the first call in a series of calls varied significantly depending on the number of calls that followed, suggesting that the crows planned their response and the number of calls from the first call onwards. Finally, the researchers assessed the trajectory of the crows’ errors and found that the errors fell into two categories: stutters (where the bird repeats a call) and skips (where the bird forgets a call). This suggests that when birds make mistakes, they usually start with the correct plan in mind, but sometimes lose track along the way.
Overall, their experiments suggest that carrion crows have a sophisticated ability to vocalize or refrain from vocalization in response to arbitrary cues, such as counting aloud, much like young children.
But the study has limitations. The authors didn’t directly measure arousal, which could still be a factor in the birds’ responses, Liao said. It’s also possible that the birds were tracking the duration of the call rather than individual syllables when responding, Cantlon said. If so, the birds may not actually have the ability to understand one-to-one associations between calls and several things, and may simply associate duration with a stimulus. More research is needed to know for sure.
Liao plans to conduct additional experiments to determine how wild crows use vocalization numbers, and also hopes to investigate the underlying brain systems that underpin this newly discovered ability: “The bird lineage diverged from the primate lineage more than 300 million years ago. We have evolved dramatically different brain structures. It will be very interesting to see how different brains come up with similar behaviors.”
In the future, what we learn about crows may help us better understand ourselves. While mathematics is a “defining feature” of human cognition, “we didn’t invent our own way of thinking entirely,” Cantlon says. “Everything about being human has a context, and that’s something we can observe in modern species. If we look at the different branches of the evolutionary tree, we can begin to trace the history of our own thinking.”
