Bantu expansion took place amid advances and alliances – 11/30/2023 – Science

The analysis of the DNA of thousands of current Africans and some who lived hundreds of years ago helped to draw a genetic portrait of the expansion of the Bantu, a group that is the origin of around a third of Africa’s population and also of the majority of Brazilians whose ancestors were brought from the mainland.

Genome data indicates that the Bantu farmers’ journey, which began in West Africa around 5,000 years ago, followed a route that traversed the Congo’s rainforests and absorbed ancient hunter-gatherer and pastoral people along its path.

The result was the diversification of a wide range of related cultures, which today are the most important in a strip that goes from the Atlantic coast to the Indian coast, in countries such as Angola, Mozambique, Kenya, Zimbabwe and South Africa, among others. In total, around 350 million Africans speak Bantu languages.

Details of the work have just been published in the scientific journal Nature, one of the most important in the world. The work was coordinated by Carina Schlebusch and Cesar Fortes-Lima, both linked to the Human Evolution Program at Uppsala University, in Sweden.

The duo and their collaborators analyzed the DNA of 1,763 individuals born in 14 African countries, the majority of which belonged to Bantu ethnicities. The data also includes the complete genome of 12 individuals who lived at the end of the Iron Age in Africa, with ages ranging up to around 700 years before the present.

In many ways, the situation of the Bantu resembles that of the Indo-Europeans, a people who appear to be behind the origins of almost all European languages, from Portuguese to Russian. Comparative analyzes carried out by linguists since the 19th century have shown that a wide range of territory in tropical and subtropical Africa is inhabited by people who speak languages ​​descended from a remote common ancestor, which has spread and diversified over the centuries.

This phenomenon of linguistic expansion, when it is detectable, probably happened in a relatively recent period of prehistory, since, over longer periods, clues about the kinship between languages ​​tend to disappear. Furthermore, the pattern of diversity of related languages ​​often gives clues about their place of origin. In general, the regions where there is a greater concentration of diversity tend to be the linguistic “cradles”, while this diversity becomes diluted as the languages ​​move away from the original nucleus.

This process can unfold in several ways. The ancestral language can spread through the migration of its speakers to new lands, but it can also happen that the original language spreads because of its political, economic and cultural influence.

The genomic data, combined with the linguistic data, make it clear that the phenomenon of Bantu expansion is more in line with the first scenario. Initially leaving the region between present-day Nigeria and Cameroon, the first Bantu groups headed east and south.

“The Bantu populations initially used advanced livestock and agricultural techniques and, later, began to use ceramics and metals,” he explained to Sheet Cesar Fortes-Lima, whose family comes from Cape Verde —which explains his Portuguese name— and who grew up in Spain.

“Since its initial expansion, its genomic diversity patterns have progressively decreased up to the limits of its distribution. These patterns are also correlated with a decrease in linguistic diversity in populations further away from western and central Africa”, he summarizes.

The areas to which the Bantu expanded were not population voids, which means that a complex process of miscegenation took place with the people who already inhabited these regions. It is something that may have involved military advances, alliances, commercial exchanges and several other elements. “In west Africa, the miscegenation was with hunter-gatherer populations; in the west, mostly with populations that speak Nilo-Saharan and Afro-Asian languages [parentes dos idiomas do Sudão e da Etiópia, respectivamente]; in the south, with those of Khoisan languages [famosos por seus “cliques”, ou estalos de língua]”, says Fortes-Lima.

“Ethnic mixing patterns show some classic signs of asymmetry between female and male lineages,” says Carina Schlebusch. “Previous studies have shown that there was a significant incorporation of local women into the expanding Bantu groups.”

According to the researcher, although the recently published study did not obtain DNA from very ancient groups, this should change soon. “In Africa, despite climate challenges [que tende a degradar o material genético], we are increasingly discovering viable samples of genetic material. Given advances in technology, we can expect major growth in DNA studies from African archaeological sites in the near future.”