Crows are capable of conscious thought like humans.

Crows are highly intelligent animals with the ability to learn and remember. New research has shown that crows have the same cognitive abilities and sense of the world as humans.

Scientists say this is called primary consciousness , or sensory consciousness. It has previously only been demonstrated in primates, meaning we may have to rethink our understanding of how consciousness arises, in addition to looking at the brains of birds.

'Our results open up a new perspective on the evolution of cognition and its neurobiological constraints ,' said animal physiologist Andreas Nieder of the University of Tübingen.

Crows also have elementary consciousness.

Primary consciousness is the most basic form of consciousness as we classify it - awareness of the world in the present (immediate and future). It is primarily associated with the primate cerebral cortex, a complex region of the mammalian brain.

However, bird brains are structured differently than primate brains, and are much smoother than mammalian brains are layered. So while corvids—the bird family that includes crows and ravens—are incredibly intelligent, with cognitive abilities found in primates, the question remains whether they can cross the line into exceptional thinking.

Nieder and his colleagues designed an experiment to test whether birds can have subjective experiences, and tested it on two carrion crows (Corvus corone).

First, the birds were trained to respond to visual stimuli. Crows were hooked up to a display of lights, and if they saw a light, they had to move their heads to show that yes, they had seen something. Most of the lights were clear and indistinct, easy to see, and the crows reliably reported that they had seen them.

But some lights are much harder to detect—brief and faint. For these, the crows sometimes reported seeing the signals, and sometimes they didn't. This is where subjective sensory experience comes in.

For the experiment, each crow was shown about 20,000 signals, spread over dozens of sessions. Meanwhile, electrodes implanted in the crows' brains recorded their neuronal activity.

When crows recorded a 'yes' response to seeing visual stimuli, neuronal activity was recorded between seeing the light and giving the response. When the response was 'no', that increased neuronal activity was not seen. This connection was so reliable that it was possible to predict the crow's response based on brain activity.

'Neurons representing visual input without subjective components are expected to respond in the same way to a visual stimulus of constant intensity, ' said Nieder . 'However, our results clearly show that neurons at higher processing levels of the crow brain are influenced by subjective experience, or more precisely, generate subjective experience.'

The results confirm that subjective experiences are not exclusive to the primate brain. The complex layering of the mammalian brain is not a requirement for consciousness. In fact, a second new study suggests that the smoothness of the bird brain is not a sign of a lack of complexity at all.

Using 3D polarized light imaging and neural circuit tracing techniques, psychologist Martin Stacho of Ruhr-University Bochum in Germany and colleagues characterized the brain anatomy of pigeons and owls. They found that the brain structure in both birds resembles that of mammals.

It's possible that similar cognitive abilities evolved independently in birds and mammals, a phenomenon known as convergent evolution. But it's also possible that our brains are more closely related than their differences might suggest.

'Our findings suggest that it is possible that an ancient microcircuit that existed in the last common amniote core may have been evolutionarily conserved and partially modified in birds and mammals. The last common ancestor of humans and crows lived 320 million years ago. It is possible that conscious awareness arose then and has been passed down ever since. In any case, the ability to experience consciousness may be implemented in differently structured brains and independently of the cortex. This means that primary consciousness may be more common in birds and mammals than we have realized,' the researchers explain.