How Smart Are Crows Actually?

Humans like to think of ourselves as special. We point to how smart we are. Our unique brain regions show how different we are from animals and other animals. Studying bird brains isn't only showing us how smart birds can be. It's challenging old ideas of how smartness evolves in the first place, as well as how unique humans really are. Various human cultures have observed the smartness of corvids birds like crows, ravens and jays for a long time. It's taken science a little bit to catch up. It's hard to test the intelligence of animals that can't communicate with humans.

So we have to interpret their behavior to get a sense of what's going on in their. One of those is tool use. Scientists define tool use in terms of using an external object to physically interact with something and change it in some way or get information about the environment. So using a leaf to get ants out of a hole in a log or using a stick to scratch an itch.

With that definition, tool use isn't something all animals do, but it's not totally uncommon. There have been reports of birds doing this thing since at least 1930. But some birds, much like primates, take it one step further. They don't only use tools, they manufacture and combine tools. In a study published in 2002, researchers in the UK watched a new Caledonian crow make her own tool to lift a bucket. The crows in the study had been choosing between a hooked wire and a straight wire to pick up a bucket of food. But when one of the other birds stole the hooked wire rude, this little genius took the straight wire and bent it into a hook. She made her own more efficient tool.

In a 2018 paper, researchers put food in a box and taught crows that they could use a dowel to push food out. Then they took away the dowel and gave them objects that were too short to reach the food on their own but put them together and you could achieve the same effect. Half the birds figured that out. The researchers figure making tools like that may require higher cognitive abilities like planning and task coordination. In fact, most modern humans don't start to show tool innovation skills until they're between ages five and nine.

Most impressive of all, crows may even exhibit consciousness. Consciousness in this sense means not only experiencing something, but being aware that you're experiencing it. Something that historically we've only thought humans and a few other mammals can do.

In a 2020 paper, researchers in Germany showed two carrion crows a bunch of shapes. Sometimes the shapes were bright and easy to see. Sometimes they were dimmer and right at the edge of what the crow could see. Other times nothing was visible at all. The crows were trained to give a couple responses. Sometimes they would say Yes, I can see the thing. While other times they were supposed to respond when they could not see it. But the real key was what was happening in the Crows brains.

The term neural correlates of consciousness refers to the neuron activity required for a conscious experience and only that specific, conscious experience. Scientists study the neural correlates of consciousness by looking for brain activity. That's different when someone reports being aware of some stimulus versus when they don't. Now, here's the key to this research. When you get right at the edge of what brightness you're capable of seeing, sometimes you'll see the shape and sometimes you won't.

So the researchers weren't so much looking for whether the Crows brains saw the shape they were looking for, whether the crow was going to say if they saw it. Certain neurons in the Crows brains had a bigger response. When the crow was going to say they did see the shape, whether or not it had actually been on the screen versus when they were going to say they didn't see the shape, even if it had actually been there.

So scientists think those neurons that say, yes, I saw something are a neural correlate of consciousness. There is some debate over this, but neural correlates of consciousness typically involve the cerebral cortex, specifically the prefrontal cortex. The prefrontal cortex is the very front part of mammals brains that's critical for complex functions like attention, impulse control and flexibility. But bird brains don't have the right structure to count as a prefrontal cortex in the additional sense.

Instead, the neurons in the Crows brains were in the Nidopallium Caudolateral or NCL. Anatomically, it looks different from the PFC, but functionally the two regions seem to be similar, much like the PFC. The NCL receives signals from sensory areas and sends out signals to the motor parts of the brain and plays a role in making decisions, assigning values to things, working memory and understanding numbers.

One Scientists in the 1990s compared it to computers. Macs and PCs are wired differently and process things differently, but in the end they serve the same purpose and do the same things because they're so different. It's unlikely that this type of intelligence and brain connectivity evolved before birds and mammals split apart 320 million years ago. Instead, similar evolutionary pressures may have led to the NCL and the PFC evolving totally separately.

So for animals in multiple niches, there was so much value in developing consciousness that brains ended up getting to the same capabilities just in different ways. Cephalopods like octopuses are also super smart, also show behaviors that look like consciousness and also have brains that are completely different from mammals or birds.

So these behaviors and functions might have evolved totally separately at least three times, which means humans might not be all that exceptional after all. That's good news, though, because it means there are even more animals to study to understand how our super smart brains developed.

Sources:

https://www.sciencedirect.com/science/article/abs/pii/S0003347208000122

https://www.bioteach.ubc.ca/TeachingResources/GeneralScience/CrowsToolPaper.pdf

https://www.nature.com/articles/s41598-018-33458-z

https://www.researchgate.net/publication/262913171_An_Exploration_of_Play_Behaviors_in_Raven_Nestlings

https://www.science.org/doi/10.1126/science.abb1447

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6842945/

Author: Douglas Jones