Counting, for human beings, is one of the first things we learn about mathematics: 1, 2, 3… But, what about animals? There is increasing scientific evidence showing that other primates, and even birds and fish, are also capable of discerning between quantities that differ by a single element and at least counting to five.
Now, a recent study by scientists at the University of Bonn in Germany and published in the journal Scientific Reports shows that fish can also be good at math: cichlids (a popular and colorful aquarium fish) and rays (very common in our oceans) can also distinguish between quantities that differ by a single element. They can count to five.
Mathematical training for fish
Could fish perform simple mathematical operations? To find out, the researchers trained the animals to perform simple addition and subtraction. In doing so, they had to increase or decrease a starting value by 1. The color blue symbolized addition and the color yellow , subtraction.
The fish were shown cards with either blue or yellow shapes, and were then presented with two doors containing cards with different numbers of shapes; one of them was the correct answer. If the fish swam through the correct gate, it was rewarded.
That fish of the zebra species mbuna ( Maylandia zebra ), a species of cichlid fish, and rays, were capable of adding and subtracting one of the numbers from one to five. The experiments were carried out with eight such fish and eight freshwater rays. On average, the mbuna zebra learned to do these operations after 28 sessions and the stripes after 68 sessions. But they got it .
“The animals then had to recognize the number of represented objects and, at the same time, infer the slide rule from their color,” says Vera Schluessel, co-author of the study. “They had to keep both in working memory when the original image was swapped with the two resulting images. And then they had to decide on the correct outcome. Overall, it’s a feat that requires complex thinking skills .”
Were they just as good at adding as they were at subtracting?
The researchers found that the fish generally did well on math ‘homework’, although they learned addition much faster than subtraction, and the performance of individual fish varied more among the mbuna zebras than among the rays, they said. the authors.
In conclusion, the ability to “count” and perform simple arithmetic processes is not only present in humans, non-human primates, and birds, but also in invertebrates such as bees and spiders , and, unsurprisingly, also in fish , both teleosts and elasmobranchs,’” the researchers wrote in their paper.
Their findings highlight that the numerical abilities of fish are on par with those of other vertebrate and invertebrate species and further confirmation that humans tend to underestimate other species, especially those outside of our immediate family or relatives. mammals in general.
Reference: V. Schluessel, N. Kreuter, IM Gosemann, E. Schmidt. Cichlids and stingrays can add and subtract ‘one’ in the number space from one to five. Scientific Reports, 2022; 12 (1) DOI: 10.1038/s41598-022-07552-2