The key finding
A 2026 review published in Neuroscience and Biobehavioral Reviews traces the evolutionary origins of imagination by examining the default mode network (DMN), the brain system central to human imaginative thinking. The authors identify two major neural innovations that occurred at the base of the mammalian lineage approximately 200 million years ago: the emergence of the neocortex and a substantial reorganization of the hippocampus. These parallel evolutionary changes—including the development of 3D organization, canonical microcircuits, expanded pyramidal neurons, and dedicated granular neuron compartments—appear to have laid the groundwork for the complex imagination we associate with mammals today.
What the study looked like
This research is an evolutionary neuroscience review that synthesizes existing anatomical, behavioral, and neuroimaging data across species. Rather than conducting new experiments, the authors examined comparative brain anatomy across vertebrates, focusing on structural differences between mammals and other animal groups. They traced how the default mode network—identified through modern brain imaging studies in humans—might have emerged from ancestral brain structures. The review encompasses evidence from paleontology, developmental neuroscience, and behavioral studies that have attempted to measure imagination-like capacities in both human and non-human animals. By comparing brain organization across the evolutionary tree, the authors built a framework for understanding which neural features are necessary for imagination and when these features first appeared in evolutionary history.
Why researchers think this happened
The authors propose that previous neuroscience research has underestimated the hippocampus’s role in shaping the mammalian brain, focusing too heavily on its functions in memory consolidation and replay while overlooking its contribution to imagination. They suggest the hippocampus and neocortex co-evolved through parallel modifications, creating the structural foundation for the DMN. The emergence of these structures wasn’t simply an incremental change but represented fundamental innovations in how information could be processed. The canonical microcircuit—a repeating pattern of neural connections—and the 3D organization of these brain regions may have enabled new forms of mental simulation and internal model-building. Interestingly, the authors predict that birds, which evolved separately from mammals, likely developed a functionally similar network through convergent evolution, suggesting that imagination-supporting brain architecture can arise through different evolutionary pathways when similar environmental or cognitive pressures exist.
How to read this carefully
This is a theoretical review synthesizing comparative anatomy rather than presenting new experimental data, so the conclusions rely on inference from structural similarities and differences. The connection between specific brain structures and the subjective experience of imagination remains indirect—we can observe neural architecture but cannot directly access the mental experiences of other species. The paper acknowledges that behavioral tests for imagination in animals have proven “insufficient for inferring the level and scope of imagination,” highlighting an ongoing challenge in comparative cognition research. Additionally, the authors note that findings “could be construed as indicators of imagination” in various species, using carefully hedged language that reflects genuine scientific uncertainty. The proposed bird DMN equivalent, while plausible given avian cognitive sophistication, awaits detailed confirmation through targeted research.
What this means for everyday life
Understanding imagination’s deep evolutionary roots changes how we might think about this seemingly uniquely human capacity. The recognition that imagination emerges from specific, ancient brain structures suggests it’s not merely a cultural or learned skill but is supported by dedicated neural hardware that took millions of years to evolve. This perspective might make us more appreciative of our brain’s ability to mentally time-travel, simulate scenarios, and create—capacities we often take for granted in daily planning, creativity, and problem-solving. The study also invites humility about human exceptionalism: if the structural foundations for imagination exist across mammals and potentially in birds through convergent evolution, then many more species may possess some form of imaginative capacity than we typically acknowledge. Given this, it might be worth considering how we evaluate animal cognition and consciousness, potentially recognizing more continuity between human and animal mental experiences than sharp dividing lines.