Bantu people came from Congo, genetic data shows

This is a relatively well-known story. About 4,000 years ago, a band of Bantu speakers left West Africa and moved to colonise half of Africa.

They pushed through the Congo rainforest spreading to southern and eastern Africa.

Some eventually settled in what is modern-day Kenya. They migrated further from Kenya along the Indian Ocean to eastern South Africa.

The Bantu Expansion is considered the greatest migration event in Africa’s prehistory.

But this journey is still a source of dispute. It was weaved in the 1950s by colonial historians who found pottery and iron tools they associated with the Bantu, along this route.

However, new genetic tests of old skeletons and modern Bantu speakers appear to support the idea of ‘Bantu expansion’.

The findings, available on the preprint server BioRxiv, also have implications for understanding health conditions common in Bantu people.

Genetic researchers sampled the DNA of 1,740 Africans, including 1,487 Bantu speakers from 14 African countries including Kenya, and generated whole-genome sequences from 12 Late Iron Age skeletons.

The results appear to support the Bantu migration from western Africa, with current-day Zambia and the DR Congo as possible crossroads of interaction.

This research, done by researchers mostly from European universities, and a few from Zambia, DRC and South Africa, is titled, “The genetic legacy of the expansion of Bantu-speaking peoples in Africa.”

“Our data support a large demic expansion of Bantu-speaking populations with ancestry from western Africa spreading through the Congo rainforest of central Africa to eastern and southern Africa in a serial founder fashion,” the authors say.

They add; “This finding is supported by patterns of decreasing genetic diversity and increasing genetic distance from their point of origin as well as admixture dates with local groups that decrease with distance from western Africa.”

However, genome sequencing, although important for unearthing human dispersal, does not give the full story.

Many scientists who study human origins still would prefer fossils over a genealogical tree.

Dr Freda M’Mbogori, the president of the Pan-African Archaeological Association, told The Star the advent of DNA sequencing marks an important chapter in the understanding of human development and evolution.

However, scientists must blend DNA analysis with archaeological and fossil evidence to try and create a coherent whole, she said.

“What is going on now is very important. It's a new way of looking at things and it's very informative. So it's going to add value to what we've thought before,” she said on the sidelines of the DNA conference at the National Museums of Kenya, in Nairobi.

Dr Freda said the Bantu origin story needs more studies because there are various theories, including that East African Bantus came from Egypt.

“So if someone says that the Bantu migrated from Egypt, do we see that  in the genetic makeup of the bones that we excavated, of the people that we think are Bantu, or are we talking about admixture?”

Dr Freda, now a senior archaeologist at the NMK and former country director of the British Institute in Eastern Africa, also recommends more DNA analysis on people and fossils from other regions of Africa.

“If we talk about Niger-Congo, have we compared what we found from Niger-Congo with anything else, which is not Niger-Congo, to say it's completely different? Then that can give us the evidence that we are looking for,” she said.

Prof Mary Prendergast, an archaeologist from US Rice University, who is researching the earliest origins and spread of pastoralism in Kenya, said genetics alone offer a narrow and biased view of the past.

She called for combined genetic, archaeological, bioarchaeological, linguistic, and historical lines of evidence.

“The recent increase in archaeogenetics research in Africa has led to important new insights on population history, while also rekindling longstanding archaeological critiques of a population genetics approach to the past,” she said.

Geneticists usually rely on the DNA of many people living along the migratory routes of interest.

DNA of long-dead people can still be found in fossils and skeletons thousands of years old.

Almost all DNA— 99.9 per cent – is the same from person to person. It is the last 0.1 per cent that has telltale differences.

 A comparison of these differences in different populations can yield vital clues to human ancestry and migration.