Scientists at Ruhr University Bochum have uncovered compelling evidence about one of evolution's greatest mysteries: why consciousness developed in some species but not others. Their groundbreaking research examines the evolutionary advantages of conscious experience and reveals that birds may have solved the puzzle of awareness through a completely different brain architecture than mammals Phys.org.
The question of consciousness has puzzled scientists for decades, but new research suggests the answer lies not in what consciousness is, but rather in what purpose it serves. According to Professors Albert Newen and Onur Güntürkün, understanding the function of consciousness is essential to explaining why oak trees remained non-conscious while crows developed sophisticated awareness. The research, published in the journal Philosophical Transactions of the Royal Society B: Biological Sciences, challenges long-held assumptions about brain structure and conscious experience, demonstrating that evolution can achieve similar solutions through remarkably different pathways.
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Three Levels of Consciousness Serve Different Survival Purposes
Newen and Carlos Montemayor have identified three distinct types of consciousness, each serving unique evolutionary functions. The first and most primitive is basic arousal, which developed to trigger alarm responses in life-threatening situations. This fundamental form enables organisms to recognize bodily damage through pain - an extraordinarily efficient mechanism for detecting threats to survival. When an animal feels pain from an injury, this conscious experience immediately signals danger and triggers defensive responses like fleeing or freezing.
The second evolutionary stage brought general alertness, allowing organisms to focus selectively on important stimuli while filtering out less relevant information. This capability enables a creature to notice smoke during a conversation and immediately shift attention to search for fire. Beyond simple cause-and-effect learning, targeted alertness permits the identification of complex correlations and scientific relationships in the environment. This advancement represents a crucial step in cognitive evolution, enabling more sophisticated interactions with the world.
The third and most advanced form is reflexive self-consciousness, which allows organisms to reflect on themselves, their past experiences, and potential futures. Humans develop this ability around 18 months of age, as demonstrated by the classic mirror test where toddlers recognize their own reflection. Some animals, including chimpanzees, dolphins, and remarkably, magpies, have also passed this test. This form of consciousness enables better social integration and coordination with others, suggesting that awareness evolved partly to facilitate complex social behaviors.
The researchers used the experimental of the "mirror-audience test" in roosters to measure their self-consciousness. The tested rooster was placed in an arena divided by a transparent glass (A,C) or a mirror (B,D). (Maldarelli & Gunturkun/Philosophical Transactions of the Royal Society B: Biological Sciences)
Birds Achieved Consciousness Without a Cerebral Cortex
Perhaps the most surprising discovery involves avian consciousness. Gianmarco Maldarelli and Onur Güntürkün demonstrate that birds possess fundamental forms of conscious perception despite lacking the cerebral cortex that mammals rely upon for awareness. When pigeons encounter ambiguous visual stimuli, they shift between different interpretations just as humans do. More remarkably, crows display nerve signals that correspond to their subjective perception rather than the physical stimulus itself - a hallmark of conscious experience.
The avian brain contains functional structures that meet theoretical requirements for conscious processing through entirely different architecture. The NCL (nidopallium caudolaterale), which serves as the bird equivalent to the mammalian prefrontal cortex, enables highly integrated and flexible information processing. The connectome of the avian forebrain—mapping all information flows between brain regions—shares striking similarities with mammalian brains, meeting many criteria of established consciousness theories like the Global Neuronal Workspace theory.
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Recent experiments reveal different types of self-perception in birds beyond the traditional mirror test. While some corvid species pass the mirror test, other ecologically relevant experiments have shown additional forms of self-consciousness in different bird species. Pigeons and chickens can differentiate between their mirror reflections and actual conspecifics, adjusting their behavior according to context - evidence of situational, basic self-consciousness that mirrors capacities previously thought exclusive to mammals.
Ancient brain structure evolution theory of Scala Naturae showing brain development proceeding from simple to more complicated with the addition of new brain regions as evolution progressed. This erroneous view is compared with a modern understanding of brain structure evolution that reveals a basic common structure evolved in the vertebrate brain and various regions expanded to accommodate each specific animal's needs. (Pablo Carlos Budassi/CC BY-SA 4.0)
Consciousness Emerged Earlier and More Widely Than Previously Believed
The implications of this research extend far beyond understanding birds. These findings suggest that consciousness represents a much older and more widespread evolutionary phenomenon than scientists previously assumed. The fact that birds developed conscious processing without a cerebral cortex demonstrates that different brain structures can achieve similar functional solutions - a principle that fundamentally reshapes our understanding of how awareness evolves.
This discovery also raises profound questions about consciousness in other species. If birds with their radically different brain architecture can achieve awareness, what other animals might possess forms of consciousness that we have failed to recognize? The research team suggests that scientists may need to look beyond traditional markers of consciousness, such as specific brain structures, and instead focus on functional capabilities and behavioral indicators. This shift in perspective could revolutionize how we assess consciousness across the animal kingdom, potentially revealing awareness in species previously dismissed as simple automatons operating purely on instinct.
The research ultimately tries to answer a crucial question of the evolution of consciousness as follows: consciousness evolved not as a single solution to a universal problem, but as multiple adaptive responses to various environmental and social challenges. Species that developed consciousness gained significant survival advantages through improved threat detection, flexible learning capabilities, and enhanced social coordination. Meanwhile, organisms like oak trees, which solved survival challenges through entirely different strategies such as chemical signaling and structural adaptations, never required conscious awareness.
Top image: AI Generated representation of a woman and her consciousness. Source: AI Visual Vault/Adobe Stock
By Gary Manners
References
Maldarelli, G., & Güntürkün, O. 2025. Conscious birds. Philosophical Transactions of the Royal Society B: Biological Sciences. Available at: https://royalsocietypublishing.org/rstb/article/380/1939/20240308/235178/Conscious-birdsConscious-birds
Newen, A., & Montemayor, C. 2025. Three types of phenomenal consciousness and their functional roles: unfolding the ALARM theory of consciousness. Philosophical Transactions of the Royal Society B: Biological Sciences. Available at: https://royalsocietypublishing.org/rstb/article/380/1939/20240314/235161/Three-types-of-phenomenal-consciousness-and-their
Phys.org. 2025. Examining why some species developed consciousness while others remained non-conscious. Available at: https://phys.org/news/2025-11-species-consciousness-conscious.html
