@WA -- you're right, the article doesn't go into intelligence. My broader point was that I thought the study was cool, but a bit scientifically dicey in its conclusions. The evolution of intelligence and numerical abilities was one interesting tangent that struck me.

@antinous -- actually, I don't think there's a line between humans and animals -- if there's a moat, then we couldn't use animal models to understand how cognitive abilities in humans might evolve -- you'd have to stick exclusively with humans. (In the same way we couldn't use lab rats to test cancer treatments if we didn't expect those treatments to work in a similar way in rats as humans because we are both mammals with a long shared evolutionary history). Comparative studies look for shared and dissimilar traits in both close and distantly related organisms to understand the particular history of whatever organism is being studied. As humans, we have a (maybe narcissistic) drive to understand the biological underpinnings of our own consciousness. One tool we can apply is tracking when and where various complex behaviors emerge in the tree of life -- because we're part of it.

So I study (drum roll?)-- fish behavior. Seriously. Numerical discrimination in animals is super cool -- examples of it help us understand mechanisms that might underlie the evolution of our own intelligence. As MalcolmKass posits, we have other examples of fish (namely swordtails) that can numerically discriminate based on the proportion of their visual field that is stimulated. In the case of the swordtails, they can distinguish the number of black bars on the side of a rival and make decisions about the rival's likely level of aggression (more bars = much more aggressive). And mosquito fish are actually VERY closely related to swordtails. Amphibians do it too -- one of my undergrads this past summer conducted an experiment that demonstrated that female salamanders (but not males) prefer to hunt in vials that contain 6 food items to vials with 5 food items -- probably because as the daphnia bounce around, the visual field receives more stimulation from 6 than 5. Which just goes to show that we often discount the abilities of animals to make complex decisions -- mosquito fish, sword tails and salamanders can all make decisions using relative information.

BUT -- Calling numerical discrimination at this level "math" isn't accurate and science requires precision language. It's a fascinating window into possible origins for complex numerical operations and symbolic logic, and suggests a much longer evolutionary history for these abilities than anyone imagined ... but it's still not "math."