None of the experiments in the article seem indicative of animals/crows understanding the concept of zero as a symbol for nothing. All animals understand the co

None of the experiments in the article seem indicative of animals/crows understanding the concept of zero as a symbol for nothing. All animals understand the concept of "none" or "not present", and can possibly count, but they don't necessarily map a symbol to represent absence. > The crows mixed up a blank screen more often with images of a single dot than they did with images of two, three or four dots. This can very well happen even if there is no understanding of zero as a symbol. You're looking for nothing, and the screen with 1 dot is almost that - in terms of the existing symbol occupying the least space, closest to nothing. Not evidence of a mapping of nothing to a symbol at all.