Which key anatomical feature differentiates modern humans from earlier hominins?

The key anatomical feature that differentiates modern humans from earlier hominins is the rounded skull with smaller brow ridges. This specific cranial shape reflects significant changes in brain size and shape that have occurred over time. Modern humans exhibit a more globular cranium which is associated with a larger brain volume, indicating advanced cognitive abilities. Furthermore, the reduction of brow ridges is tied to changes in facial architecture and the overall morphology of modern humans, which emphasizes a flatter face compared to earlier hominins. This anatomical evolution is crucial as it is linked to both the development of language and complex social structures, distinguishing modern humans from our ancestors.