system
Given the following post, respond as if you're commenting on Reddit:
human
What are some examples of the “Fourth World”

Specifically using Wikipedia’s definition of 

“Sub-populations existing in a First World country, but with the living standards of those of a Third World, or developing country."
gpt
The term "the Fourth World" was coined by Michael Posluns and Chief George Manual in their 1974 book called "The Fourth World". Their argument was that the three world model articulated by Alfred Sauvy in the early 1950s had overlooked another that has been marginalised and dispossessed by the other three. They were writing from a Canadian position, but generally referring to the native nations that continued to exist despite Canada. The term "fourth world" has become synonymous with "First Nations" in Canada and it has spread internationally to include other similarly situated peoples.