Following the evolution of Homo sapiens across Africa using a uniparental genetic guide

Abstract

The origin and evolution of modern humans in Africa has reached a multidisciplinary consensus but the age and regions where it originated and evolved are current topics of discussion. In this study I put forward an integrative model guided by the phylogeny and phylogeography of mitochondrial DNA (and Y-chromosome) haplogroups. I propose an early origin of modern humans in northwest Africa in a temporal window of 257-345 thousand years ago. A first population split in central Africa around 175-288 thousand years ago. A subsequent northward spread with additional population subdivisions during a long statistical interval that culminated in a first successful out of Africa migration around 130 thousand years ago. A population constriction in southwest Asia motivated an early return to Africa between 79 and 107 thousand years ago. This ample Eurasian-ebb to Africa, detected by mitochondrial haplogroup L3 and Y-chromosome haplogroup E preceded other later and geographically more limited Eurasian backflows. The archaeological and fossil finds that could be coetaneous to this molecular journey have been integrated into this interdisciplinary model.

Early male and female footprints of modern humans across Eurasia and Australasia

“…Early modern humans left Africa and spread across the Middle East during the humid MIS5e stage around 130 kya 24 . The split of mtDNA haplogroups L3’4 and the origin of Y-chromosome macrohaplogroup CT (Tables 1 and 2) were the molecular uniparental markers of that event.…”

“…However, based on the coalescent ages obtained for different Eurasian lineages using fossil-calibrated human evolutionary rates, the geneticists usually consider any human dispersal in Eurasia earlier than 60 kya as genetically unsuccessful events which did not contributed to the present-day human genetic pool 8 , but it should be taken into account that there is still no unanimous acceptance of what mutation rate should be applicable in each case for the estimation of the evolutionary rate 20,21 and that a strong time-dependent effect has been detected on the human evolutionary rate 22 , most probably due to changes in the effective population size 23 showing evolutionary rates slower than the used mean for Paleolithic times and faster than the mean for recent historic times 24 . Under these, more permissive genetic grounds, a more conciliatory model, based on the phylogeny and phylogeography of uniparental genetic markers, has been proposed recently to explain the potential evolutionary and migratory processes of modern humans across the African continent 24 continuing outside of Africa and into the Middle East around 120-130 Kya 25 , which harmonically integrate the uniparental genetic data with the fossil and archaeological records. In this study we extend this model to explain the early spread of modern humans across Eurasia and into Near Oceania and Australia trying to demonstrate that the times and human movements deduced from the mtDNA and Y-chromosome phylogenies and phylogeographies are compatible with the human prehistoric path unearthed by the Archaeology.…”

The Middle Stone Age of Atlantic Africa: A critical review

“…5). This makes it even more plausible to suppose that something of significant importance to human evolution may have happened here, somewhere at some point, whether anatomically, behaviorally, or cognitively (Cabrera, 2023).…”