We’re beginning to find out more about how animals that don’t really “think” much can keep track of numbers, when needed.
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?
Takehome: It’s long been known by observation that many life forms can count, up to a point. The question of how, exactly, they do it is the science goal at present.
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.