On the whole, treatment of indigenous populations varied to some extent. However, I think its important to understand the views of Europeans of the time, when trying to understand the actions taken. European consciousness was, in the upper and ruling classes, deeply entrenched in the views of Social Darwinism. Therefore, each European nation saw that it had a divine right to save the lesser races of the world. This notion provided the justification for the actions of the Empire builders of the 19th century. This could also perhaps explain the decisions made by Europeans of the day- influenced by a now redundant theory, they were entirely convinced of their actions. The treatment of the indigenous peoples was really a side issue (aside from some exceptions, such as the investigation into Belgian conduct in the Congo).

Prior to the First World War, European society was experiencing massive changes at all levels. For example, the worlds of Harry Kessler (one of the most socially connected men of the pre-1914 period) recounted-

Something very great, the old, the cosmopolitan, still predominantly agrarian and feudal Europe, the world of beautiful women, gallant kings, the dynastic combinations, the European of the 18th century and the Holy Alliance was growing weak and old, dying out; and something new, young, energetic, and still unimaginable was in the offing. We felt it like frost, like a spring in our limbs, the one with muffled pain, and the other keen joy.' (Kessler, Journey to the Abyss, 11)

The ruling classes were visibly very concerned with preserving the status quo, and Empire building was just one of the means doing so. By unifying a nation behind an idea of its own greatness. The Germans used Weltpolitik (see Hew Strachans 'To War' for an excellent annd engrossing section about Weltpolitik), the British used the idea of Empire as a means for galvanizing working class support for the ruling elite, the French looked to Empire to regain public faith following the loss of the Franco-Prussian war. Take for example, the German case of Weltpolitik-

For 40 years, France has pursued a grandiose policy. It has secured an immense Empire for itself in the world. It is everywhere. During this time, an inactive Germany did not follow this example and today it needs its place in the sun... Everyday Germany see its population growing leaps and bounds; its navy, its trade and industry are making unparalleled developments... it is forced to expand somehow or other; it has not yet found that 'place in the sun' which it is due. (German Chancellor Bethman Hollweg to the French Ambassador to Berlin Jules Cambon in 'The Foreign Policy of Imperial Germany', Fritz Fischer, page 26)

Therefore, with the strains of European society changing, coupled with a very wide spread acknowledgement of Social-Darwinism, it is hard to give much credence to any belief that any of the colonies would have fared any better under a different ruling nation: because the well being of seemingly inferior races would surely have come a distant second to the need to secure the dynasties and regimes that were buckling under the strain of a changing Europe. In the great race of Empire building and maintenance, there was little time for humanitarian considerations.