“But they are smart enough to be able to learn this abstract category.” “These animals may not need the concept of numerosity zero – unlike countable numerosity – in their day-to-day living,” study co-author Andreas Nieder told IFLS. In a paper published this month in the Journal of Neuroscience, scientists have shown that the brainy birds can not only understand zero as a numerical quantity – as “something” rather than “nothing” – but they also may well have an idea of it as the smallest number on a mental number line. So it may come as a surprise that humans are not the only animal who can understand the concept: there’s convincing evidence that honeybees can conceptualize zero as a quantity, and so can the (already impressively numerate) rhesus macaque. And according to new research from the University of Tübingen in Germany, crows can too. You’d say something like “pass the opium, Esagil-kin-apli, all my sheep are dead, I’ve no sheep left, it’s been a hell of a day.” Even if all your sheep died from some sheep plague, you wouldn’t say “I have zero sheep” like some nerd doing a math test. And when you think about it, that’s not surprising – after all, if you’re an ancient Babylonian trying to keep track of your sheep, zero is pretty useless. It was discovered way later than numbers like two or 14 or even 3.9 or 64/13. It’s hard to imagine a world without zero, but it’s actually a surprisingly recent idea.

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