The longstanding assumption that Neanderthals possessed inferior cognitive abilities compared to modern humans may need fundamental revision. This reassessment challenges decades of anthropological thinking about what distinguished our species from our closest extinct relatives. New analysis of endocranial reconstructions reveals that brain structure differences between Neanderthals and modern humans fall within the normal variation observed among contemporary human populations. The researchers found no meaningful anatomical basis for assuming cognitive inferiority in our extinct cousins. More significantly, the study highlights the weak correlation between brain structure and actual cognitive performance, undermining the practice of inferring intelligence from fossil skull measurements. This finding suggests that previous assessments of Neanderthal mental capabilities may have been systematically biased by outdated assumptions about brain-behavior relationships. The implications extend beyond paleontology into contemporary neuroscience and cognitive assessment. If brain structure correlates only weakly with cognitive ability even within our own species, this calls into question how we evaluate intelligence across populations and individuals. For understanding human cognitive evolution, this work suggests that Neanderthals may have possessed sophisticated problem-solving abilities, social cognition, and adaptive intelligence that we have consistently underestimated. Rather than representing a cognitive stepping stone to modern human intelligence, Neanderthals may have achieved comparable mental sophistication through different but equally effective neural pathways. This perspective reshapes our understanding of what made early human populations successful and suggests that cognitive diversity, rather than linear progression, characterized our evolutionary past.