See: Animals Count and Use Zero. How Far Does Their Number Sense Go?
Note: I have mentioned the ability of various non-human animals to count and assess quantity in previous articles in my “Reason” series, but this article goes so much farther than my brief reflections.
See full article by Jordana Cepelewicz, Quanta Magazine "Animals Count and Use Zero. How Far Does Their Number Sense Go?"
Summary by ChatGPT:
Overview
While the ability to understand numbers is traditionally seen as a hallmark of human intelligence — closely linked to language and abstract reasoning — mounting evidence shows that many animals, across a wide range of taxa, possess surprisingly advanced numerical skills. Recent research has even demonstrated that some animals, including crows, monkeys, and honeybees, understand the abstract concept of zero — a notion that even human children struggle with and which appeared relatively late in human cultural history.
Widespread Numerical Abilities in Animals
Studies have shown that:
Bees count landmarks when navigating.
Lionesses assess the number of roars from other prides before deciding to attack.
Ants count their steps.
Spiders track the number of prey caught in their webs.
Frogs increase the number of pulses in their mating calls in a competitive escalation.
These findings suggest that a basic sense of numerosity — the mental representation of set size — is widespread and likely evolutionarily ancient. Animals can distinguish not only "more vs. less" but can also differentiate between specific small quantities (e.g., 2 vs. 3, 15 vs. 20). According to neuroscientist Giorgio Vallortigara, numerosity is a general, foundational cognitive capacity.
Approximate Number System and Neural Evidence
Animals appear to rely on an approximate number system:
They are better at distinguishing quantities that are numerically far apart (e.g., 3 vs. 6) than those that are close (e.g., 5 vs. 6).
This system is less precise at higher values.
Monkeys, for example, have neurons in their prefrontal cortex tuned to specific numerosities. A neuron might fire most for three dots but still respond weakly to two or four — showing an analog, gradient-like encoding.
Humans possess a similar system but also map numbers onto symbols, which enables more precise and complex mathematical reasoning.
Arithmetic and Beyond
Several species appear capable of simple arithmetic:
Chicks: Without training, newly hatched chicks choose to approach screens hiding more objects after witnessing items being moved between screens — suggesting a form of spontaneous addition or subtraction.
Monkeys: Continue to check a food cache until the last item is removed, implying they are tracking subtractions.
Honeybees: Can be trained to add or subtract 1, based on color-coded rules (e.g., blue = add one, yellow = subtract one). This requires them to learn symbolic associations and perform operations, even though such behavior hasn’t yet been observed in the wild.
The Concept of Zero
Understanding zero is especially noteworthy because:
It is not just about identifying a small quantity, but recognizing nothingness as a quantitative concept.
Human children typically take longer to understand zero than other numbers.
In historical mathematics, zero was a late invention, appearing in recorded human cultures only by the 7th century.
But studies have found:
Monkeys have neurons that respond selectively to zero, and they confuse zero most often with one rather than two — suggesting they mentally locate zero next to one on a conceptual number line.
Bees, with only ~1 million neurons, also exhibit behavioral evidence of understanding zero. They too mistake zero more frequently for one than two, and can learn that zero is "less" than other quantities.
Crows, lacking a mammalian brain structure like the prefrontal cortex, have a different brain region (the pallium) that represents zero similarly — suggesting convergent evolution of numerical cognition.
Convergent Evolution and Brain Structures
Despite differences in neuroanatomy:
Birds like crows do not have a neocortex or prefrontal cortex but have independently evolved complex cognitive capacities.
In both monkeys and crows, specific neurons represent zero along the same lines as other numerosities.
This could mean that numerical abstraction, including zero, may be a computational necessity — a cognitive function that evolved independently in different species because it is a useful solution to common problems.
Some researchers speculate there may be limited ways the brain can encode numerosity, so evolution has arrived at similar strategies multiple times. This is supported by recent findings in zebra fish, whose brains also seem to have dedicated regions for representing numerosity — though their ability to grasp zero has not yet been tested.
Symbolic Understanding: Where Animals Hit the Limit
While animals demonstrate many abstract numerical capabilities, symbolic reasoning remains a dividing line:
Some animals can be trained to associate symbols with numbers (e.g., chimpanzees touching digits in order).
But manipulating those symbols to perform operations (like "2 + 3 = 5") has not yet been convincingly shown in animals.
This ability is routine in human children — and marks a leap from numerosity to full symbolic mathematics.
Why Do Animals Need Numbers?
The evolutionary value of numerosity is still under exploration. Some proposed functions include:
Foraging: Knowing when no food remains (zero) signals the need to search elsewhere.
Predator assessment: Recognizing that two entered and none left implies danger.
Resource competition and social navigation may also benefit from quantity discrimination.
Others argue that number sense might be a byproduct of general object-recognition and comparison systems in the brain — a kind of emergent property of broader visual and spatial cognition.
The Genetic Frontier
Some researchers are now exploring the genetic basis of number sense:
Studies in humans have identified genes linked to dyscalculia, a math learning disability.
Researchers are now manipulating these genes in zebra fish to understand how numerosity might be encoded at the molecular level — a potential breakthrough in linking genetics to cognition.
Conclusion
Animals across diverse species demonstrate a surprisingly deep and abstract understanding of number — including the elusive concept of zero. While their cognitive abilities differ from human symbolic mathematics, the shared capacity for numerosity may form an evolutionary foundation upon which human mathematical reasoning was built.
This growing body of research suggests that numerical cognition is neither uniquely human nor exclusively cultural, but rather a widespread biological capacity — evolved many times, in many ways, in response to the computational demands of life.
In animals numbers are sort of hardwired (analog), same goes for "zero" as in empty. They do not seem to have ability to do arithmetic as a symbolic operation, their arithmetic is analog (if at all). One could argue that humans pre-numbering had similar problem. You need to invent symbols/numbers to do numerical (which is really symbol manipulation) math.