View of the village of Kuboes, on the border of South Africa and Namibia. DNA samples were collected from Nama individuals who have historically lived in the region.
Brenna Henn/UC Davis.
Research first published in Nature in 2023 shows just how wide of the mark the Bronze Age authors of the Bible’s origin myths were when they guessed at human origins. Of course, in the absence of any knowledge or understanding of the true age of Earth, the history of life on it, or the existence of deep human ancestry, their guesses were no better than we would expect from people trying to explain the world with folklore rather than evidence.
In fact, as the evidence in the 2023 paper by a team co-led by Professor Brenna Henn of the University of California, Davis, and Simon Gravel of McGill University, Montreal, Quebec, Canada, shows, modern humans did not emerge from a single founding couple, or even from one simple, isolated ancestral population. Instead, our origins lie in a complex, dynamic network of human groups that diversified within Africa, evolved in partial isolation, and later exchanged genes as populations moved and merged.
In that respect, human evolution resembles other cases in nature where populations diverge, remain partly distinct, and yet continue to exchange genes — such as the carrion crow/hooded crow Corvus complex, the Eurasian complex of the great tit (Parus major) and its related forms, and the circumpolar herring gull/lesser black-backed gull Larus complex. These examples show evolution not as a neat ladder or a set of separately created “kinds”, but as a branching, reticulating process in which boundaries can be blurred by gene flow.
This process of diversification and later remixing continued in Eurasia, where Homo sapiens interbred with Neanderthals, Denisovans and, possibly, other human populations. Neanderthals eventually disappeared as a distinct population, or were partly absorbed into expanding Homo sapiens populations, around 40,000 years ago.
Far from the single ancestral couple that may have seemed intuitive to parochial Bronze Age pastoralists, modern humanity emerged from a population history that looks less like a single line of descent and more like a tangled bush with cross-linking branches.
The researchers reached this conclusion by analysing DNA sequenced from saliva samples from 44 modern Nama individuals from southern Africa, an Indigenous population known to carry exceptionally high levels of genetic diversity compared with many other modern groups. From that genetic data, the team developed a model suggesting that the earliest detectable split among ancestral human populations occurred between 120,000 and 135,000 years ago, after two or more weakly differentiated Homo populations had already been interbreeding for hundreds of thousands of years.
Even after that split, migration continued between the populations, producing what the researchers describe as a “weakly structured stem” for modern human origins in Africa. Rather than a single stem from which humanity simply sprouted, human evolution is better understood as a reticulated process: branching, merging, and branching again.

































