Crows So Smart They Understand Concept of Zero

We have known for some time now that crows are highly intelligent and previous scientific studies have already demonstrated that crows possess primary, or sensory, consciousness—the ability possessed by humans and some primates to merge memories to think in terms of past and present. Now a new scientific study has demonstrated that crows, like bees, can comprehend the concept of zero.


Study overview

Scientists already know that crows can distinguish quantities (1, 2, 3, etc.) from one another.  Previous studies have demonstrated that crows have certain neurons which light up when they see certain quantities displayed. One dot fires a certain neuron, two another, three another, and four dots, yet another. To test whether crows could comprehend zero as a numerical value, the researchers showed crows two displays of dots, each display containing between zero and four. The crows were trained to indicate if the two displays showed the same value. While they did this, researchers monitored their brain activity. When the crows saw “zero” dots, their brains fired a new neuron recognizing this new “quantity.” (source)


Researchers’ Conclusions

The conception of “nothing” as number “zero” is celebrated as one of the greatest achievements in mathematics. To explore whether precursors of zero-like concepts can be found in vertebrates with a cerebrum that anatomically differs starkly from our primate brain, we investigated this in carrion crows. We show that crows can grasp the empty set as a null numerical quantity that is mentally represented next to number one. Moreover, we show that single neurons in an associative avian cerebral region specifically respond to the empty set and show the same physiological characteristics as for countable quantities. This suggests that zero as a quantitative category can also be implemented in the anatomically distinct end-brain circuitry of birds that evolved based on convergent evolution. (source)


Journal reference: Maximilian E. Kirschhock, Helen M. Ditz and Andreas Nieder. Behavioral and Neuronal Representation of Numerosity Zero in the Crow,