DNA analysis of children in western and central Africa shows that in ancient times there were at least three main human populations, the genes of which are present in the peoples living today in Central Africa, its southern part, as well as all other modern people: they were genetically dissimilar, especially between about 250,000 and 200,000 years ago.
It turns out that there was also a fourth "branch" - an unknown human population that appeared at the same time and left a weak genetic trace in modern people inhabiting western and eastern parts of Africa, scientists led by evolutionary geneticists Mark Lipson and David Reich from Harvard Medical School. In this fourth population, traces of the DNA of hominid populations that existed before the appearance of the human species on Earth were found. Possibly Neanderthals. The genetic data in the new study is "the only ancient DNA record found in western Africa, sub-Saharan Africa."
This genetic evidence for long-dead children is consistent with a scenario in which different populations of Homo sapiens emerged in different parts of Africa about 300,000 years ago, followed by a continent-wide mixing.
Previous genetic research by evolutionary geneticist Pont Skoglund of the Francis Crick Institute in London identified a human population dating back over 200,000 years ago that was the ancestor of later groups of hunter-gatherers in the rainforest of western and central Africa, growing south of the Sahara. The new study provides additional evidence for a fourth lineage: the ancient children whose DNA is described in the study have several genes from those ancient rainforest ancestors.
Lipson's team took DNA from four children buried in Shum Lak, a stone sanctuary in northwest Cameroon. There, during excavations in the 1980s and 1990s, stone tools and other artifacts were found. In total, 18 human skeletons were found in Shum Lak, most of which were children. Some burials are about 8000 years old, others are about 3000 years old.
A 1994 excavation in a stone shelter in Cameroon uncovered the skeletons of two boys, buried about 8,000 years ago. Their DNA suggests that human populations in several parts of Africa were genetically distinct from each other over 200,000 years ago.
Another discovery concerns one of Shum Lucky's teens - a teenager buried about 8,000 years ago. This boy possessed a rare set of Y chromosomes, which are passed from father to son. Today, this paternal “ancestry” is virtually non-existent outside of a couple of ethnic groups living in western Cameroon. Previous research indicates that this male genetic line is between 200,000 and 300,000 years old, making it the oldest known.
It is unclear why only one of the three ancient African boys described in the new study descended from that ancient lineage.