Crows Can Pass This Ancient Test from Aesop's Fables

Every child is familiar with Aesop's Fables for their lessons on morality. It turns out that the ancient tales aren't just good life advice — they're also handy cognitive tests. Scientists have used one particular fable over and over to see if animals have a sense of cause and effect. Some pass with flying colors, but others, not so much.

Ancient Tales for Modern Tests

If you're not familiar, Aesop's Fables are a collection of morality tales — 725 of them, to be exact — dating back to at least ancient Greece. In each one, an animal faces a human-like situation where its decisions inevitably teach some practical lesson about life.

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In "The Crow and the Pitcher," a crow is nearly dead from thirst when it happens upon a pitcher used to pour water. Rapturously, it dunks its beak into the pitcher — only to find that there was hardly any water in it. The little water that was there was too far down inside the vessel for the crow to reach it. Suddenly, the crow has a stroke of genius and drops a small pebble into the pitcher. Then another. And another. It drops so many pebbles that eventually, the water level is high enough to reach its beak, and the crow finally quenches its thirst. The moral of the story? Little by little does the trick.

Scientists love this fable because it's a great illustration of cause and effect. The crow realizes dropping a stone into the pitcher will displace the water and thereby raise its level in the container, and proceeds to do that over and over until it reaches its goal. That shows a causal understanding, which requires a certain amount of cognitive finesse that not all animals have. That's why study after study has relied on it to understand how various animals see the world.

Rook, Check Mate

It's probably not surprising that the first animal scientists thought to try this test on was a crow. Well, a rook, to be precise, which is a bird in the same family as crows. Around 2009, University of London comparative psychologists Nathan Emery and Christopher Bird (seems like an appropriate name for a bird researcher!) set out to determine if these birds could actually achieve what Aesop's crow did. They gave each of four rooks a clear plastic tube that had a worm floating near the bottom, next to a pile of stones. The amount of water and the sizes of the stones varied among the birds. Two solved the problem on their first try, two others gave up before trying again, but all eventually were able to drop enough stones in the tube to get the worm.

Since then, scientists have used this test in myriad ways. They tested young children (only children aged 5 and older performed as well as the birds). They tested a different species of crow (they passed easily). They tried using objects of different sizes and densities, using tubes of different volumes, and seeing how using water compared to using sand. Over and over, members of the crow family proved that they could pass this essential test of cause and effect.

In 2017, University of Wyoming researchers decided to use another wily animal: the raccoon. They didn't quite measure up to the crows, but the researchers thought that wasn't necessarily a sign they weren't as intelligent. Only two of seven raccoons figured out that they could pick up stones and drop them in the water to get a treat. A third, however, did something that shows a different kind of intelligence (and should impress anti-establishment renegades everywhere): "During final trials, Raccoon 22 innovated a unique solution by gripping the inner rim of the apparatus with her forepaws and, while rocking her body back and forth, overturned the entire apparatus and retrieved the reward," the researchers wrote. Raccoon 22 is our spirit animal.