"These two phenomena--retention of type with change of language and retention of language with change of type--apparently opposed to each other--often go hand in hand. An example is the distribution of the Arabs along the north coast of Africa. On the whole, the Arab element has retained its language, but at the same time intermarriages with the native races were common, so that the descendants of the Arabs have retained their old [Arab] language and have changed their type. On the other hand, the natives have to a certain extent given up their own languages, but have continued to intermarry among themselves, and have thus preserved their type." (Boas, 1963, p. 140-1)