Caledonian crows are famed for their smarts. They have been
known to properly interpret reflections to find food and their
ability to make and use tools rivals chimpanzees for
But these brainy birds have been beaten in a recent intelligence
test by a bunch of babies. It’s a rare failure, but it appears they
are unable to interpret cause and effect to create new solutions
without direct experience of the events.
If you observed a brick falling onto a button that dispensed
food, you would quickly realise that you didn’t need the brick to
get the food. You could just push the button yourself.
You have observed a sequence of cause and effect, and although
you haven’t directly experienced it, you can figure out what’s
going on and get the food.
Caledonian crows, according to a new study published in Proceedings of the Royal Society B: Biological
Sciences, aren’t able to do this.
“The crows are great as solving certain types of problems but,
as our new study shows, struggle at others,” lead author Alex
Taylor told Wired.co.uk via email. “Discovering the limits of their
cognition allows us to get a better understanding of how
intelligence evolves, and which aspects our our cognition are
Taylor and his colleagues have studied Caledonian crows for
years, and have been the source of numerous papers on their
intelligence, including a March paper that replicated
Aesop’s Fable of a thirsty crow using stones to raise the water
level in a half-filled container.
Indeed a 2009 study showed that the crows are able to understand cause
and effect quite well. Crows that received food as an effect of
pushing a platform with their beak then learned to use other tools,
like stones, to move the platform if it was out of reach.
The crucial difference, said Taylor, is that this required a
direct experience. The crows had previously pushed the platform
“Animals are very good at learning from their own experience, or
via observing the effects of others (social learning),” he said.
“But so far only humans appear to be able to simply observe an
effect in the world, and, without reference to their own behaviour
or another humans, then create a novel behaviour to cause the
To test this hypothesis, Taylor set up an experiment where a
block sat above a rotating cylinder. If the block fell on to the
cylinder, a portion of meat would become available to the
Initially, the block itself was baited with meat. If the crow
tried to grab the meat, the block would fall, turning the cylinder
and making a different portion of meat available as a reward.
But when an unbaited block was placed beside the cylinder. All
the crows had to do in order to get the prize of meat was to pick
it up and drop it on the cylinder. Despite having observed the
block turning the cylinder previously they were unable to complete
the task as it required them to do something different than
A group of two-year-old human babies, on the other hand, were
able to solve the problem with ease. The same experiment was
repeated with a marble instead of meat. On the first try, a baited
block was placed above the cylinder. When the baby tried to grab
it, the block would fall, the cylinder would turn and then a second
marble would become available.
When an unbaited block was placed beside the cylinder, the
babies figured out that they could just pick it up and drop it on
the cylinder in order to get a marble.
“The key issue here is understanding causality via observation
alone, rather than experience,” said Taylor. “Humans can observe an
effect of the wind blowing, such as causing fruit to fall from a
tree, and then create behaviour to recreate the same effect, such
as shaking the branch (or see a domino hit a stone, and the pick up
the stone and drop it to create the same effect).”
“This behavioural freedom may be one of our most
under-appreciated cognitive abilities,” he added.
Despite their wits, it seems like this round is Caledonian crows
zero, human babies one. In your face, nature.