Evolution doesn't care about better it only cares about adaptation and survival. The most intelligent were often stoned to death or didn't have children, thus becoming a genetc dead end. More intelligent people are often more neurotic and depressed because they see the what others cannot; this also makes it difficult to sustain relationships.

Generally, you are always best suited to live amongst a population/ethnicity of similar intelligence. Europeans evolved in harsh (but not too harsh), cold, resource limited, environments that kicked their ass until they evolved the intelligence to kick nature's ass back with concepts like agriculture and industrialisation. Adapting to such an environment also develops the part of the brain that handles delayed gratification; extremely important for planning and surviving winters with clever resource management. All these features also conducive to developing universal ethics (via Christianity) and by extension modern civilisation.

Africans evolved in temperate or tropical environments where resources were plentiful. They never needed to adapt their intelligence for agriculture or anything advanced because food was hanging off trees.

None of this means one is better than the other, just means one is adapted to different environments. This is why third worlders fail in Western civilisation without the welfare state. Conversely westerners fail in third world environments because the higher intelligence makes you a target and you end up getting purged like farmers in Zimbabwe.

This is all generalisations based on populations though and can't be used to judge individuals. It can however be used to predict the implications of mass third world immigration: we won't be able to sustain our civilisation.