I'm hoping for one, as I can't find anything remotely like a source for belief in "four current human species" on google. I think someone's research may be faulty, but not sure yet whose research.
From the article:
During the 19th and early 20th centuries, anthropologists and biologists naively divided all people into geographical groups on the basis of what they saw as the regular occurrence together of selected traits. They were using the typological model which has the same basis as the commonly used categories of race today. This approach focuses on a small number of traits that are readily observable from a distance such as skin color, hair form, body build, and stature. The roots of this typological model for classifying people go back at least to the 18th century Swedish naturalist, Carolus Linnaeus. He proposed the existence of four biological varieties or races of humans corresponding to geographic regions:
Homo sapiens Eoropeus albescens ("white" people from Europe)
Homo sapiens Africanus negreus ("black" people from Africa)
Homo sapiens Asiaticus fucus ("dark" people from Asia)
Homo sapiens Americanus rubescens ("red" people from the Americas
The typological model is based on what is now known to be a false assumption concerning the nature of human variation--that is, that we can be unambiguously assigned to a "race" on the basis of selected traits. In fact, when we look at specific individuals, we often run into difficulty trying to categorize them. For example, on the basis of skin color, we might put them into one "race" and on the basis of nose shape, body form, or blood type, they might go into others.