In the previous ten chapters we have examined a number of well-established language families, such as Indo-European, Semitic, Turkic, Austronesian and others. A question that may be asked at this point is whether any of these language families are related to each other inside even bigger groupings. Such groupings are alternatively referred to as clades, phyla (singular: phylum) or macro language families. Here, I will use the latter term.

The question of such macro families has occupied many an inquisitive mind and hypotheses are plentiful. Various rather far-fetched theories, such as Amerindian, Nostratic, Eurasiatic and Proto-World, have received much attention not only in professional academic circles but in the popular press as well and have been featured in Atlantic Monthly, Nature, Science, Scientific American, US News and World Report, The New York Times and in BBC and PBS television documentaries. While some proposed long-distance relationships and macro families are quite well proven and as a result widely accepted among historical linguists, others are more controversial, and yet others are so far fetched that they are not accepted by linguists other than those who originally proposed them.