The power of contemporary African DNA: Exploring models of human evolution and health in Africa

Abstract

It is generally accepted that humans evolved in Africa, but several opposing conceptual models representing our origins have been proposed. We shed light on the divergence of human populations on the African continent and challenge traditional models, suggesting a new framework -represented by a tangled vine with offshoots -in which stem populations separated but continually exchanged genetic material. This work would not have been possible without sequencing the most genetically diverse human genomes in the world; contemporary African DNA is not only key to understanding deep human history, but is also central to answering other health-related questions. Genetic models of human evolutionThe study of human evolution has been a subject of great interest as we seek to understand the origins and history of our species. One of the fundamental organising concepts in biology is the 'tree of life', which was the predominant model of human evolution for many years. This model of human population divergence from a single ancestral population in Africa was supported by the existing genetic data, but was difficult to align with the evidence of Homo sapiens fossils and archaeological sites across the continent. 1 Fossils and archaeological records indicate the presence of anatomically modern humans across Africa between 300 000 and 100 000 years ago. Several key fossils, such as those found at Jebel Irhoud in Morocco, Herto in Ethiopia, and Klasies River in South Africa, demonstrate that anatomical features that originated in Homo sapiens were present throughout the continent during this period. Additionally, archaeological sites associated with Homo sapiens, particularly from the Middle Stone Age, are widely distributed across Africa, including the site with the oldest footprint identified. 2 Whether these populations represent the direct ancestors of contemporary humans or represent isolated local populations remains unanswered. Due to recent advances in population genetic tools, more complex modelling and inference using larger data sets have become possible. 3