University College cognitive psychology prof Brian Butterworth, author of Can fish count? (Basic Books, 2022), talks about animal number sense in a recent article in Psyche:

He offers many examples of animals counting single digit numbers but then helpfully addresses the question of how they do it. We are talking here about a variety of very different types of neurological equipment — insects vs. amphibians, for example. Neuroscientists are beginning to pinpoint specific brain functions associated with counting for specific tasks:

Female túngara frogs benefit by mating with the male that can produce six croaks in one breath, over the male that can manage only five, because this is an indicator of respiratory fitness. Naturally, the male will try to outcroak his competitor by counting the number of croaks and adding one, to the limit of his breath.

Brian Butterworth, “A basic sense of numbers is shared by countless creatures” at Psyche (October 12, 2022)

How?

In the case of the túngara frog, where counting is essential for mating and reproduction, the biologist Gary Rose discovered a neuron in the inferior colliculus, part of the auditory system, that checks that the number of croaks has the correct rate to be an advertisement call – and not some other type of call. Another type of neuron counts the croaks.

Brian Butterworth, “A basic sense of numbers is shared by countless creatures” at Psyche (October 12, 2022)

What about the fish that — for better protection — join large shoals rather than small ones?

Fish have brains that are even more different from our own but, as mentioned, small fish, such as zebrafish, can benefit from a number sense in choosing a larger shoal. Scientists are beginning to discover how their tiny brains do this: it turns out that neurons in the zebrafish pallium respond to changes in visible number.

Brian Butterworth, “A basic sense of numbers is shared by countless creatures” at Psyche (October 12, 2022)

Dr. Butterworth goes a little far when he suggests that dyscalculia (hopelessness at math) in humans may stretch back to “the common ancestor of ants and humans”:

One thing that my colleagues and I discovered in working with fish was that some individual fish seem to be much worse on numerical tasks than others of the same species. We are now investigating whether there is a genetic basis to these individual differences. This could help explain why around 5 per cent of people – those with dyscalculia – have serious trouble with even simple number tasks. It is possible that this learning disability, rather like colour vision deficiency, is the result of one or more genetic variants that makes the number mechanism less efficient in representing numbers, which in turn makes learning arithmetic more difficult.

Brian Butterworth, “A basic sense of numbers is shared by countless creatures” at Psyche (October 12, 2022)

He then concedes that “even if we have inherited a basic number sense from distant ancestors, there are some big differences between humans and other creatures.” Most certainly. Algebra, geometry, and calculus are among them.

More to the point, there is a variety of suggested reasons why some humans are not very good at math (ten are listed here) and none of them date back to common ancestry with ants or fish. They mostly relate to the circumstances under which math is taught and/or used in a human setting.

That said, Butterworth’s and other researchers’ work is encouraging in that it helps us understand how, exactly, life forms that do not really think in a human sense can handle numerical tasks anyway, on account of the way their brains are organized.

Knowing the neuroscience behind a life form’s abilities is much more useful for science than, say, a declaration that a number sense “enables the frog to secure a better mate” or “helps the zebrafish survive.” Doubtless, those observations are correct. But the science question is, how does the life form secure that advantage?

You may also wish to read: Are our neurons really wired for numbers? Some neuroscientists say they have shown hardwiring in studies of crows and macaques but others say no, these life forms differ too much. For humans, the story is even more complex. Abstract math, driven by curiosity, may result in practical everyday benefits, not the other way around.