Human Story - How did the Bantu people become so widespread?

In the post on Sunday I remarked in passing how striking it is that such a large part of Africa speaks closely related languages, and offered up the theory that it was the result of a huge population expansion, but then I just dropped it and moved on to talking about Trevor Noah or something.

I mean... it's tough not to.

But let's rewind a second. It's Human Story today. How did Bantu-speaking people get everywhere they are today?

That turns out not to be the easiest question to answer - most of the evidence we have for the expansion at all is just the similarity between the Bantu languages. The thought process goes that if people in Cameroon, Kenya, and Cape Town are all speaking clearly similar languages, they must have been speaking the same language fairly recently. So it goes in historical linguistics; there's simply no other force that could have made them so similar from that distance. Based on linguistic reconstruction, it's pretty clear that the Bantu speakers began about 4,000 years ago in the Niger-Congo heartland, in modern Cameroon, from there expanding south and east into essentially the whole southern half of Africa, absorbing or displacing sparser hunter-gatherer populations like the Congolese pygmies and Khoisan bushmen. Unfortunately, studying the languages has pretty limited ability to fill in any of the juicy details about how or why the expansion happened. This is the point in the discussion where linguists usually turn things over to geneticists and archaeologists, but their findings are... mixed.

ConLing - What are the Bantu languages?

Subsaharan Africa is one of the most linguistically diverse areas in the world, with about two thousand languages (give or take a thousand, depending on who's counting). Further, many of the recognized language "families," like the Nilo-Saharan and Khoisan groups, have no agreed-upon family tree, being grouped on the basis of vague similarities, or of not being clearly related to other established clades.

Part of the uncertainty comes from a lack of data, but even if we knew everything about these languages, they still might not fit neatly into groups - the millennia of close contact and free movement among ethnolinguistic groups means that most African languages might not slot into neat, linear family trees the same way that the languages of more recent migrants, like Indo-Europeans, do. Given this backdrop, it's shocking that right smack in the middle of Subsaharan Africa is a huge swath of area, with as many as a third of all Africans speaking a set of unmistakably close linguistic cousins, sharing ideosyncratic grammatical features and most of their vocabulary.

A Shona mother in Zimbabwe will call her infant a mwana. For a Swahili speaker in Kenya, on the other side of the Bantu zone, the word for "child" is also mwana. Coincidence? Linguists think not.