The researchers did not expect this result, but it is not an April Fools joke: according to the findings of scientists at the University of Bonn, fish can count, as the university announced on Friday. According to the study, published in the journal Scientific Reports, cichlids and stingrays can add and subtract up to five.
Bonn zoologist Vera Schlüssel had both species perform simple additions and subtractions in her study. “They had to increase or decrease an initial value by one,” explained Key. To do this, she and her team used methods that have already been tried and tested on other animal species to test math skills.
They presented the fish with a collection of geometric shapes, such as four squares. If these were colored blue, it meant “add one”. Yellow colored squares meant “subtract one”. After that, the tasks were hidden and the animals were shown new pictures – one with five and one with three squares. If they swam to the right image – that is, by adding five blue squares instead of four – the fish were rewarded with food. If they answered wrong, they got nothing.
no cerebral cortex
To test whether the fish could also apply their knowledge to new tasks, the researchers changed their tasks after the learning phase. It turned out that the fish could now also solve tasks three plus one and three minus one. The fish would also have correctly calculated on a combination of various geometric shapes such as a square, triangle and circle.
The researchers were also surprised by the performance of the perch and stingray, as they do not have a cerebral cortex. In humans, this accounts for the most complex cognitive tasks. Also, it is not known that the two fish species require a good understanding of numbers. Study leader Schlüssel sees her work as confirmation that humans tend to underestimate other species. (apa)