Causal understanding of water displacement by a crow
New Caledonian crows have demonstrated a significant, though not complete, understanding of water displacement, similar to that of 5 to 7-year-old children. In an experiment based on Aesop's fable, the crows showed they could discern how to raise water levels to access a reward by choosing to drop stones into a tube of water rather than sand, selecting sinking over floating objects, and preferring solid over hollow objects. They also chose tubes with higher water levels for this task. However, their understanding was imperfect, as they struggled with more complex tasks involving the width of tubes and deceptive causal cues in a U-shaped apparatus. This indicates that while they have a grasp of some causal relationships, their cognitive abilities in this area are not absolute.
Aesop's fables are a collection of stories credited to Aesop, an enslaved person and storyteller believed to have lived in ancient Greece between 620 and 564 BCE. These fables are short tales that typically feature animals as characters and convey a moral lesson or truth.
One of the most relevant fables concerning the study is "The Crow and the Pitcher." In this story, a thirsty crow comes across a pitcher with water at the bottom, beyond the reach of its beak. After failing to push the pitcher over, the crow has an idea: it drops pebbles into the pitcher one by one, causing the water level to rise until the crow can drink it. This fable illustrates a moral about ingenuity and problem-solving — it's often interpreted to mean that necessity is the mother of invention or that intelligence and persistence can overcome physical limitations.
For more information: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0092895
Original Video: https://vimeo.com/595587776
Cheke LG, Clayton NS, Gray RD (2014) Using the Aesop's Fable Paradigm to Investigate Causal Understanding of Water Displacement by New Caledonian Crows. PLoS ONE 9(3): e92895. doi:10.1371/journal.pone.0092895