One explanation for the evolution of the same neural framework in such different brains is simply that it is an effective solution to a common computer problem. “It’s actually exciting because it suggests it’s just the best way,” Avarguès-Weber said. There may be physical or internal constraints on how the brain can process zero and other numbers. “There might be a very limited number of ways you can create a mechanism to encode numbers,” Vallortigara said.
Still, just because crows and apes seem to code an abstract concept like zero in the same way doesn’t mean it’s the only way. “It could be that different solutions have been invented in the course of natural history, in the course of biological evolution, to perform similar calculations,” Vallortigara said. Researchers will have to study other animals to find out. In a paper just appeared in Cerebral cortex, for example, Vallortigara and his colleagues have identified a region of the brain in zebrafish that appears to correlate with numbering, although they have yet to test the animals’ ability to score zero.
Bees might also have some surprises in store as the basis for their numbers becomes better understood. In a study published last year, MaBouDi and his colleagues “have shown that the drone counts through a fundamentally different strategy” when presented with up to four objects, he said. He believes their findings suggest that the mechanisms underlying bees’ understanding of numbers, including zero, may indeed be very different from what has been observed so far.
But perhaps the most fundamental question about digital abstraction in the brains of various animals is not how this ability works, but why it exists. Why should animals recognize specific amounts? Why has evolution constantly ensured that animals can understand not only that four is less than five, but that “four squares” are in some way conceptually the same as “four circles”?
According to Vallortigara, one of the reasons could be that arithmetic ends up being so important. “Animals must continually do arithmetic. Even simple animals, ”he said. “If you have an abstract representation of the numbering, that’s very easy to do. Abstraction of digital information allows the brain to perform additional calculations much more efficiently.
This may also be where the zero fits. If two predators enter an environment and only one exits, the area remains dangerous. Rugani assumes that an animal must not only be able to subtract in this situation, but also interpret zero as “the result of a previously performed numeric or protonumeric subtraction” – which the animal can then associate with particular environmental conditions. In this case, “every time you hit the lowest value, which is zero, the environment is safe,” Rugani said. When searching for food, zero may correspond to a need to search in a different place.
Nieder, however, is not convinced. He does not see a pressing need for animals to understand zero as a numbering, as viewing it as an absence should generally suffice. “I don’t think animals use zero numbering as a quantity in their everyday life,” he said.
Another possibility is that an understanding of zero – and numbering more broadly – might simply have emerged from the brain’s need to recognize visual objects in the environment. In 2019, when Nieder and his colleagues formed an artificial network to recognize objects in images, the ability to discriminate the number of elements was born spontaneously, apparently as a by-product of this more general task.
An overview of the building blocks of mathematics
For Nieder, the presence of talents for digital abstraction in animals indicates “that there is already something in the brains of these animals that can provide an evolutionary basis for what, in us, humans can develop into one. full understanding of the number zero. . “
But as impressive as the animals’ accomplishments are, he pointed out that there are crucial differences between how animals have conceptualized number and how humans do. We don’t just understand quantities; we link them to arbitrary number symbols. A set of five objects is not the same as the number 5, Nieder said, and the empty set is not the same as 0.