World's major language families

The geographical distribution of families is a reflection of the historical evolution of their speakers. Thus, most of the large families of languages seem to have expanded thanks to agricultural or technological "revolutions" of some other kind. The Neolithic revolution led to the expansion of Afro-Asiatic languages in Africa and the Middle East, the Sino-Tibetan languages in the Far East and, according to Renfrew's theory, the expansion of Indo-European languages in Western Eurasia.

The improvement of navigation techniques allowed the speakers of the Austronesian languages to expand from the island of Taiwan throughout Oceania, even reaching Madagascar, in front of the African continent. European imperialism brought the Indo-European languages to America and to many areas of Africa, Oceania and, to a lesser extent, Asia. Apparently, the use of iron and other technologies would have allowed the Niger-Congo languages to become prevalent in Africa, displacing the speakers of other families now few in number, such as the Nilo-Saharan languages or the Khoisan.

At present, the two largest linguistic families by number of speakers, Indo-European languages and Sino-Tibetan languages together account for a number of speakers equivalent to 75% of humanity. On the other hand, among the indigenous languages of America, for example, many language families barely exceed a few thousand speakers.