We humans have not yet discovered why or why we dream, although we have suspicions: that it serves to consolidate memory, to process emotions, to prepare ourselves for possible situations that we may experience while awake or that it is simply a side effect of chaotic activity. of our sleeping brain… and that is of no use. However, there is something we do know: we are not the only ones who dream.
Rubén Rial, emeritus professor of Physiology at the University of the Balearic Islands, asks us to think of a dog; If he is young, even better. When they sleep, these animals move their paws, cry and bark. In this way they show us that they dream. This empirical example – which was the same one that Aristotle used to launch his hypothesis that “not only men dream” – has later been verified by scientific research that today has made it possible to reach the certainty that the ability to dream is widespread. in mammals.
During sleep, mammals show two phases: non-REM and REM (Rapid Eye Movements). During the REM phase, the brain is very active, the eyeballs move quickly, we experience small muscle jerks, and although we can also dream during the non-REM phase, the most vivid dreams occur during REM.
Does the same happen in birds? Rial explains that, currently, it is believed that birds also have REM and non-REM phases. But the evidence is only based on electroencephalographic recordings of sleeping birds. However, the professor leaves room for doubt: the electroencephalogram is not a sufficiently firm test to define non-REM or REM; allows us to doubt its real existence in birds.
Rial argues that the waves that we use to identify these stages of sleep in birds also appear in newborns, whether they are sleeping or not, as well as in awake reptiles. “This means that the signs used to distinguish sleep phases in birds can also appear in other cases and, therefore, cannot be considered absolutely certain,” he adds.
However, beyond this initial caution, Rial believes that birds probably dream; and to explain this, he suggests that we think about crows. “When a crow finds food and cannot eat it at once, what it does is hide it; but while doing so, he looks back and, if he notices that another crow is watching him, instead of hiding the food, he hides some other object, such as a stone, and then looks for another safer place to hide it, being careful. of not being observed by any competitor,” Rial illustrates.
“It is an extraordinary capacity! What crows do is deceive (when it suits them) and it takes a very high level of consciousness to be able to lie to your partner,” adds the professor. It is also known that crows are capable of using tools and that, when they want to reach food through a hole, they can use a stick or a wire, which in some cases they even bend.
For Rial, these types of actions indicate that crows, and also other birds, are capable of using tools – a capacity that chimpanzees also achieve – which suggests that the brain of birds is homologous with that of mammals.
Although the brain of birds does not have the cerebral cortex (the part of the brain responsible for higher cognitive functions, such as thinking or imagination), they have, instead, the nidopallium, a region whose capacity reaches levels similar to those of the mammalian cortex. And if the nidopallium achieves a level of intelligence sufficient to cheat, why couldn’t it also dream?
This is how Rial concludes: “The mental capacities of some birds – not all – are as high as the mental capacities of some primates and almost as those of human beings. And, if they have some mental abilities similar to ours, it is very possible that they are also capable of dreaming.” And in fact, the most recent research on bird sleep leans towards affirming this ability.
In a study conducted by researchers at the Ruhr University and the Max Planck Institute (2023), magnetic resonance imaging was used to identify brain activation patterns in sleeping pigeons and found that these birds can probably experience visions of flight when they sleep
The scientists observed, during REM sleep, great activity in those areas of the brain responsible for visual processing – including those used to analyze the environment when flying – and in the regions that process signals from the body – especially in the wings -, they explained. it’s a statement. Based on these observations, the researchers suggested that birds dream like we do during REM sleep and that they might be experiencing flight in their dream world.
The team described also suggests, as a consequence of the activation observed in the amygdala (a part of the so-called limbic system that controls emotional responses), that it is likely that birds’ dreams include emotions, just like ours.
Another important study in this regard is led by Gabriel Mindlin, director of the Dynamic Systems Laboratory of the Faculty of Exact and Natural Sciences of the University of Buenos Aires, who could have found in birds the equivalent of the vocalizations of sleeping dogs. The researcher has observed that some birds sing during sleep.
Mindlin has dedicated the last 25 years to the study of bird songs, which required mathematically modeling the vocal production system of birds and measuring the electrical activity of the muscles of the vocal apparatus of these animals. This allowed the team, in the study of sleeping birds, to detect that during sleep activation patterns appear very similar to those used by the bird to sing during the day, but that, since the appropriate respiratory patterns are not generated, no sound is produced. .
Their study focused on the mandarin diamondback (Taeniopygia guttata), a species of bird that, like humans, needs to learn to vocalize. The difference with us is that when the mandarin diamond has learned its song, it dedicates itself to repeating it day after day, without variations. And here comes the great curiosity of Mindlin’s study.
“During sleep, in addition to practicing the motor gestures used during the day, perform other new gestures; That is, he explores beyond the stereotypes used during the vigil,” explains the expert for La Vanguardia. This finding suggests that birds not only dream, but also use dreams to explore possible variants.
It should be noted in this sense that the result was somewhat different in birds that do not learn their song, but rather it is genetically programmed. The discovery in this case was that these birds also sing, but that their practices are much more similar to those used during the day. “In the benteveo (Pitangus sulphuratus), a species that does not learn, nocturnal practices are very stereotyped and similar to daytime gestures. What this suggests to us is the possibility that motor actions are linked to the possibility of learning,” states Mindlin.
But this is not all. In his latest study, the scientist went even further to listen to the sleep of birds. To achieve this, researchers from the University of Buenos Aires have used mathematical models of vocal production that translate the activity of the birds’ muscles into songs, in a remarkable synthesis exercise.
And Mindlin was moved by the result: he heard how a bird tried, in his dreams, to defend its territory, with its crest of feathers raised and emitting what, during wakefulness, would be a trill associated with confrontations. In this case, the finding would be that birds – like us – also dream about lived experiences. As to whether all of this applies to humans, Mindlin leaves the door half open: “That’s the big question. It is extremely suggestive… But it is only the beginning of this path,” the researcher closes.