THE CLEVER ONES

Raccoons prove they understand cause-and-effect by passing the Aesop’s Fable test

In Aesop’s fable “The Crow and the Pitcher,” a thirsty bird hoping to drink from a narrow vessel with just a bit of water at the bottom raises the liquid to drinking level by displacing it with pebbles. Though the crow initially despairs, with this exercise the bird learns the critical life lesson that “little by little does the trick.”

The displacement exercise from the 6th-century-BC morality tale written by a Greek slave is now used as an intelligence test in the biosciences, to measure whether creatures understand cause and effect. Crows, jays, and apes have passed. Recently, zoologist Lauren Stanton at the University of Wyoming and a team of researchers put racoons through the tests. The results, published in the November issue of Animal Cognition (pdf), were unexpected.

Little by little is smart, sure, but so is disruption. The eight animals tested weren’t all the same or equally capable. Half were wild raccoons caught and brought to the lab, and the others were lab-grown raccoons. Some were male and others female. Not all proved to be geniuses, but two of the eight did learn quickly and a third showed researchers that innovation is not the domain of humans alone.

First, the animals were presented with a long, narrow plastic tube with water and a marshmallow treat floating atop the water but out of reach. Six pebbles were placed on a platform atop the tube. Each animal was given 20 minutes to interact with the materials and figure out the solution. None could figure out displacement independently. After the animals saw displacement demonstrated by the researchers, however, two of those eight, both lab-raised males, mimicked them. In other words, they learned.

Another raccoon, a lab-raised female, did her own thing. She displaced the water but didn’t reach for the marshmallow like the others. Instead, she gripped the inner rim, jumped on top, rocked the apparatus, toppled it and hopped off to collect the treat. This feat surprised the researchers. The test was specifically designed to prevent that result; the plastic tube raccoons used were mounted on a stable square platform, yet this didn’t deter her.

The study concludes that these results are “an important first step in expanding the investigation of causal understanding” across animals. But it notes that there are limitations to measuring all creatures’ intelligence with the same tests, considering different species have different morphologies which influence their responses to the tools presented.

In other words, it’s possible humans don’t yet understand animal cognition well enough to devise exercises that reflect their abilities; we may yet find that raccoons and other animals are more intelligent than current tests results suggest. We are learning more and more, though, and we already know that we should not despair of getting better answers eventually. As Aesop wrote many years ago, “little by little does the trick.”

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