Whites probably have about 100 million fewer cerebral neurons, on average, than Asians and blacks have about 480 million fewer than whites. The black/Asian difference is especially significant because of differences in body size. Blacks with small brains in large bodies are at a serious intellectual disadvantage compared to Asians because a larger proportion of their already-smaller brains is probably occupied with basal functions and not available for conscious thought.

— Amren