These terms are rarely used in current anthropology. “Australoid,” when used, is unambiguous. “Negroid,” when used, is typically unambiguous since people take it to mean sub-Saharan African, but some people may classify numerous populations in East Africa as Negroid, too, which is problematic. Excluding skin color, East African populations with a non-Negroid facial features central tendency craniofacially cluster with Europeans before joining the sub-Saharan African or Negroid cluster.19)

Similarly, genetic analyses of East African populations such as Somalis and Ethiopians reveals major affinities to both Euro-Mediterraneans and sub-Saharan Africans.20), 21), 22), 23), 24), 25), 26) See also the following principal components analysis of African populations and neighbor-joining dendograms from Cavalli-Sforza and others' 1994 book on the history and geography of human genes:

a)

b)

c)


Therefore, numerous East African populations are not classifiable as Negroid or Caucasoid, and they certainly didn't end up as they are via a simple admixture scenario.

“Mongoloid” is a more ambiguous word. Mongols, Chinese, Koreans and Japanese would be unambiguous examples of a Mongoloid, but a popular early-to-mid 20th century tentative racial classification scheme proposed by Carleton Coon classified northeast Asians, southeast Asians, Eskimo-Siberians and Native Americans all as Mongoloid, which may make it difficult for individuals harboring a relaxed or a strict definition of a Mongoloid to effectively communicate with each other.

“Caucasoid” is the most ambiguous word in this group. It is frequently encountered in the non-anthropological scientific literature, where it refers to whites but not a biological race. “Caucasoid” in colloquial usage in Western societies also refers to whites. However, Carleton Coon's popular tentative racial classification scheme included people as far south as North Africa and as far East as India in the Caucasoid group.

We have seen above that East Indians and whites cannot be classified into the same race as per the phylogeographic criteria. There is also clinal variation from sub-Saharan Africa to Europe. Therefore, caution is required when using formerly in vogue racial terminology, especially “Caucasian.” One could talk about Caucasoid features with less ambiguity than talk about who or what is a Caucasian. For instance, a Somali or Ethiopian could be found with a Caucasoid basic face design, but whereas his facial features could be said to be Caucasoid, the person himself could not be classified as a Caucasoid in a meaningful manner.

Source: http://wiki.majorityrights.com/race