According to new research, crows can ‘count’ in the same way as toddlers

Before toddlers learn to master symbolic counting – where ‘one’ means a single object and ‘two’ means double – go through a development phase of verbal counting. At this stage, when asked how many apples are in a group of three, a young child may say “one, one, one” or “one, two, three” or “apple, apple, apple” in a form of prototype . to count. They understand that there are three apples, but they are not yet fully able to express that number only in the abstract form of ‘three’.

Inspired by this knowledge, Diana Liao, a neurobiologist and postdoctoral researcher at the University of Tübingen in Germany, decided to ask the obvious question: can crows do it too? Spoiler alert: that’s possible, according to a first study of its kind published on May 23 in the magazine Science. Carrion crows can control their vocalizations and make the number of those calls correspond to a signal, in a form of proto-counting, according to the new research.

The study adds to the growing laundry list of cognitive skills that corvids (the bird family including crows, ravens, magpies and jays) possess. The new work also helps in the search for the evolutionary origins of humans’ mathematical ability. By studying the abilities and limitations of other animals, scientists can get a better idea of ​​where and how our own math skills come from.

“It is a very nice study,” Jessica Cantlona professor of psychology at Carnegie Mellon University who researches quantitative reasoning and was not involved in the crow study, says Popular science. In humans, the connection between the vocal system and our mathematical brain is an important part of our sense of numbers. “When you start using vocalizations to represent things in the world, it changes the way you think… that [is the way that] counting arises in humans during development and over evolutionary time,” she explains. “It wasn’t clear until now that any other animal could do that,” she adds.

Previous research – usually involving pecking, button pressing, food choice, clicking on a screen, head movements or hand singing – has shown that crows, chimpanzees, monkeys, parrots, rats, honeybees, chickens and other animals have some level of quantitative reasoning, including distinguish between different amounts of things, conducting basic arithmeticeven rarely, conceptualize zero. But the level of vocal control in humans is unique among animals. Even other primates “are so bad at producing human vocalizations,” Cantlon says. ‘I think people have kind of given up on getting primates [vocalize] in quantitative reasoning tasks.”

Crows are just one entry on the long list of species that make sounds, adding to the ‘ca-caw’ phoniness of the natural world. Unlike humans, however, scientists think that most animal sounds are involuntary and instinctual: programmed at birth and provoked by external cues from the environment, Liao explains. Research in tits has shown this, for example the birds will add more “dee” syllables in their alarm calls, in the presence of larger predators, but that trend doesn’t necessarily mean the songbirds are literally measuring the size of the predator with their tweets. Instead, it is possible that the number of ‘dees’ corresponds to the amount of arousal caused by the presence of a predator, and larger threats are more alarming. Liao wanted to investigate this phenomenon in a more controlled environment, where an artificial laboratory setup would allow her and her colleagues to eliminate the role of instinctive fear and excitement.

The new study of carrion crows is the first to explicitly demonstrate that every other species except humans can link voluntary vocalizations to quantity understanding. Keeping track of clucks “isn’t like counting the number of cocks,” says Girogio Vallortigara, a neuroscientist at the University of Trento in Italy who has published on arithmetic skills in zebrafish and newborn chicks. Instead, tracking vocalizations “requires timing…and requires extensive memory and planning,” he explains. “It’s certainly an advanced cognitive ability.”

To prove what the corvids were capable of, Liao and her co-authors trained three carrion crows to associate colored Arabic numerals (1, 2, 3, and 4) with neutral auditory cues (that is, sounds that were unrelated) . natural threat or prey) with a corresponding, flexible set of vocalizations. The process took more than a year and was largely trial and error, Liao says. The researchers presented each crow with a number on a screen or a pre-recorded sound and then rewarded the bird with food if and when it produced the corresponding number of calls.

After training was completed, the crows were tested in repeated one- to two-hour sessions. Each bird, placed in front of a screen, initiated trials by pecking a target. Then, in response, a number appeared on the screen or an audio cue was played. The crows called out in response and then pecked an “enter key” on the screen to signal the end of their response. If the number of calls correctly matched the number, the crows received a tasty mealworm or birdseed pellet as a reward.

Over the course of twenty sessions each, all three crows showed that they could match their vocalizations to the signals much faster than by chance. Most of the time, the crows got it right: they showed 100% accuracy in response to the number one, more than 60% accuracy for number two, more than 50% for three, and about 40% accuracy for number four. Using a computer analysis tool, the researchers further found that the first calls in a sequence differ significantly depending on the number of calls that follow, indicating that crows plan their response and call number from the very first caw. Finally, the researchers assessed the tracks where crows got it wrong, and found that errors fell into two categories: stuttering (where birds repeat a call) and skipping (where a bird forgets one) – suggesting that when the birds are wrong, they usually start with the right plan in mind and sometimes lose track along the way.

In total, their experiments suggest that carrion crows have a sophisticated ability to make or withhold vocalizations in response to arbitrary cues, adding aloud the way toddlers do.

However, there are some limitations to the study. The authors didn’t measure arousal directly, so it could still potentially be a factor in the birds’ response, Liao says. And it’s possible that the birds followed the duration of the calls in their responses, and not the discrete syllables, Cantlon says. If that’s the case, they may not really have the ability to understand one-to-one associations between a call and a set of things; it could simply be that they associate a duration with a stimulus. Further research would be needed to know for sure.

Liao plans to conduct additional experiments to investigate how crows can use vocalization numbers in the wild, and also hopes to explore the underlying brain systems that support the newly discovered ability. “The lineage of birds diverged from the lineage of primates more than 300 million years ago. We have developed dramatically different brain architectures. It would be so interesting to see how different brains achieve similar behavior.”

What we learn about crows later can help us understand ourselves better. Math is a “defining feature” of human cognition, but “it’s not like we’ve invented ways of thinking that are completely unique,” ​​Cantlon says. “Everything about being human has a backstory, and that’s something we can observe in modern species. If we look at different branches of the evolutionary tree, we can begin to trace the history of our own thinking.”