Crows were back in the news again last week. A fascinating study was published in the Proceedings of the National Academy of Sciences suggesting that New Caledonian Crows are able to reason about hidden causal agents—connecting events to a hidden perpetrator.

But before we go any further, if you aren’t already in love with genus Corvus, please go back and read this comic. Go on, I’ll wait here.

Now then, what’s a hidden causal agent?

As humans, one of our greatest advantages is our ability to make deductions and assign agency to events in the world around us. For example, when we see the leaves on a tree rustling, our immediate thought is, “Who is doing that?” We reason that there is a causal agent behind this event. It’s a tremendous advantage in the wild, as the rustler could very well be a predator*. Agency detection is also one of our more troublesome features. This same defense mechanism can trick us into thinking there is an unseen hand behind mundane events or coincidences. (The stuff conspiracy theories are made of.)

The more we study animals, the more we find out that humans aren’t all that special, and now causal reasoning has entered the realm of our favorite corvid. The folks over at Ars Technica explain the experiment in much more depth than the comic, in which I tried to encapsulate the thought process of the crows rather than the experimental steps, but the gist is this:

In the first trial, the crows could see somebody go behind the tarp, and would then observe the threatening stick poke out from behind it. Once the person left the tarp, the crows felt secure in going for the food. In the second trial, nobody went behind the tarp, and instead the stick was manipulated from outside the room (using pulleys, apparently). The crows didn’t see anybody enter the tarp, but the stick still moved. Having not seen anybody leave the tarp, the crows acted with extreme caution, constantly eyeing the hole that the stick emerged from—sometimes to the point of aborting their attempt. Watch Alex Taylor, an evolutionary psychologist at the University of Auckland explain the test here:

It’s a pretty wild discovery of something that we take for granted, and it could be the next “mirror test” for the assessment of cognition. Of course, it could also only prove that crows have some understanding of the nature of sticks and the troublesome nature of researchers.



*Or better yet, prey.