In the most ancient crania, the occipital was the most, and the frontal region the least developed; and the increase in the elevation of the latter marked the transition from barbarous to civilized man. The occipital lobe is the visual processing center, so Neanderthals possibly required the larger occipital lobe to compensate for low light levels in Europe. Because of this, Neanderthals may have been unable to evolve the cerebellum expansion seen in early modern humans. This enlarged visual cortex also correlates with larger eyes among Neanderthals. It is possible that Neanderthals relied more on visual information, but the true purpose of the occipital bun has not yet been defined. However, some studies have found possible evolutionary purposes. In one study the occipital bun has been attributed to the enlargement of the visual cortex; this is hypothesized to be an adaptation to lower light levels found in the higher latitudes of Europe.