A concept we learned about in my Global Poverty class (and high school history classes previous) was that of the "Other." Not the kind from the Nicole Kidman movie, although it does have a great plot twist, but the kind that's important in colonialism, development, and our conception of ourselves.
We tend to define ourselves as individuals and as a society by what we are not. We are civilized. What does that mean? It means we are not savages. We are modern, because we are moving beyond tradition.
It was a large part of colonialism. Imperialists (mainly Europeans) defined themselves as modern in comparison to the "native" people of the places they occupied. There had to be a standard for comparison. The native culture was to be kept in its traditional, "pure" form, as though in a museum.
The same thing occurs today with development, with anthropological and sociological studies of other countries. Unless you are originally from that country (and even then sometimes, because you are entering in a professional capacity), you see the place from an outsider perspective. You look at the differences between yourself and them, you other-ize the people whom you are studying or helping, because that's how you remember who you are. Wherever there are differences, unfortunately, there's a hierarchy.
One of the places this is most evident is in the status of women in the West. According to Lila Abu-Lughod, "it has been accepted that, at least in the modern West, women have been the other to men's self."1 That's where feminism comes in, of course. "Feminism has been a movement devoted to helping women become selves and subjects rather than objects and men's others."
There are still difficulties, principally in the differences in experience between women in various situations, but the progress the movement has made is undeniable. The small things, the way men unconsciously (or consciously) see and treat women, however, are still there. I think that's because men still define themselves as not women. Men are not supposed to be girly, they can't cry in public, stay-at-home dads get less respect, etc. But all of those characteristics are social constructions anyway, so hopefully we can get rid of this divide.
The same applies in development work - if you're going out somewhere to help people in a "less developed" country, don't assume they're backwards. Don't assume their culture is unchanging. Don't assume they are completely different from you. Because they aren't.
1 Abu-Lughod, L, Fox, RG (ed). (1991). "Writing Against Culture" from Recapturing Anthropology: Working in the Present. School of American Research Press.