What is one negative effect colonization has on the European colonizers?

The natives are abused and dehumaized by the European colonizers.

Whatever the conditions in Africa may be, all of the characters agree that they are different from those of Europe. There is a feeling of anything-goes vigilantism that shifts the balance of power from the stewards in a “civilized” state (police, doctors, bureaucrats) to whoever is most threatening. Kurtz is physically quite a weak man, but he maintains enormous sway over the native population through his understanding of their language and his cultural and communication skills. He exploits their appreciation of him as an Other. Marlow’s men use a much more simple means of gaining authority, namely, firearms. This is the tragedy of imperialism in that the arrival of the white man heralds a new order, but in the creation of that order, they retain the tools and the authority. Black men in this book first appear as members of a chain gang, and they gain little power after that scene.