A very fundamental question was seldom asked, in either the earlier or the later period: Was there ever any realistic reason to expect the same achievements among races, classes or other subdivisions of the human species?
Could we really have expected Eskimos to have the same ability to grow pineapples as the people of Hawaii had? Could the Bedouins of the Sahara really know as much about fishing as the Polynesians of the Pacific? Could the people of the Himalayas have the same seafaring skills as people living in ports around the Mediterranean?
On a more general level, could people living in isolated mountain valleys realistically be expected to develop their own intellectual potential as fully as people living in cities that were international crossroads of commerce, cultures and ideas from around the world?
When the Spaniards discovered the Canary Islands in the 15th century, they found people of a Caucasian race living at a stone age level. Isolation and backwardness have gone together in many parts of the world, regardless of the race of the people involved.
Historical happenstances -- the fact that the Romans invaded Western Europe but not Eastern Europe, for example -- left a legacy of written languages in Western Europe that people in Eastern Europe did not have until centuries later.
But the innumerable factors affecting human achievements are not only complex and hard to untangle, they offer neither politicians nor intellectuals the opportunity to simply be on the side of the angels against the forces of evil. Factors which present no opportunity to star in a moral melodrama have often been ignored in favor of factors that do.