David Reich updated his preprint on October 13, 2026. It has a his take on the Origin of Neanderthals, and Modern Humans, a revision of the Out of Africa theory, and the dispersal of the first humans into Europe and Africa, and admixture with archaics in both places. (See it online: Hypothesis: A modern human range expansion ∼300,000 years ago had a critical role in Neandertal origins, David Reich, bioRxiv 2026.03.11.711219; doi: https://doi.org/10.64898/2026.03.11.711219)
The following map shows the outline of Reich's hypothesis. Fig. 1. in his preprint.
(a) I start with a previously proposed model for the relationship of Neandertals, Denisovans, and modern Africans in which an early modern lineage contributed mtDNA and Y chromosomes to Neandertals and ∼3-7% of the rest of the genome3. I graft onto it the deep substructure detected in people today, inferred in one study to contribute ∼80% of the ancestry of present-day Africans11, and inferred in several studies to have ended around ∼300 ka7,11,12. At bottom are estimates of divergences and population splits: range of estimated dates for the autosomes, and 95% confidence intervals for mtDNA and Y1. (Not shown: <50 ka gene flow from Neandertals and Denisovans into non-Africans, and superarchaic gene flow to Denisovans.)
(b) Schematic of what the range expansion might have looked like after ∼300 ka, with an early modern human lineage in northeast Africa or the Near East expanding both into Europe and Africa and mixing with local archaic populations; ancestry within these regions would then have homogenized due to admixture among neighbors; the red-to-blue shading indicates mixing. The European archaic range is drawn based on an estimate of the later Neandertal range. Source
Brief Summary
Reich seems to be going alone with this article. There are no other authors. It isn't revert decades of entrenched "Out Of Africanism", but the time is ripe, and this is a first step in the right direction.
This paper by David Reich upturns the classic Out Of Africa (OOA) theory. He suggests that modern humans originated around 300,000 years ago. He does not specifically pinpoint their place of origin, but, although he includes North Africa and a corridor along the Nile to Ethiopia, he has added a Eurasian range that spans the Levant, Mesopotamia, and the Caucasus.
Reich the "expansion" of an "early modern human lineage in northeast Africa or the Near East expanding both into Europe and Africa and mixing with local archaic populations; ancestry within these regions" Highlight is mine. I would imagine a group descended from Eurasian Homo erectus evolving in the Levant and then migrating into Africa.
These modern humans then moved into Europe, where they admixed with European archaics (like the Homo antecessor), originating the Neanderthals, and further south into Subsaharan Africa where they met, and mated with very ancient Archaic Africans (they had split from the other branch 1.5 million years ago).
This does away with the current story: Homo heidelbergensis was the ancestor of modern humans, Neanderthals and Denisovans. It lived in Western Eurasia and Africa. Then, 300 ky in North Africa it evolved into H. sapiens, there was a first, failed OOA migration ~150 ky ago into the Levant that introgressed human genes into Neanderthals there. Finally, 60 ky ago, modern humans left Africa and replaced, in one single burst, all other humans in the Old World.
Neanderthals descend from modern humans
Reich's take explains why Neanderthals and Denisovans are so similar, from a genetic point of view, yet differ in their mtDNA and Y-chromosome (Neanderthal's are closer to ours). The mtDNA is transmitted by mothers to children (matrilineal), and chromosome Y is patrilineal (father to son), so here we have a theory that basically states that Neanderthals descended from modern humans.
Reich notes that ancient "Neanderthals harbor 3-7% admixturefrom an early modern human lineage ∼300-200 ka"
Modern Humans from the Levant entered Europe and mated with the Archaics that lived there, the blend led to the appearance of Neanderthals, which retained 93% to 97% of the original genes (mainly autosomal), but inherited modern human mtDNA and Y-chromosomes.
Reich then proposes four different scenarios to explain how modern humans passed their uniparental markers on and replaced those in the archaic population.
Into Africa and mix with African Archaics
Another band of these Levantine modern humans moved south into deep Africa and mated with extremely ancient archaic Africans.
Here the mix was very different to the one that took place in Europe. The hybrid population that resulted from the admixture retained 80% modern human and 20% African archaic alleles.
These African Archaics come from a lineage that split 1.5 million years ago from the one that led to the modern humans in North Africa and SW Asia, they evolved separately for 1.2 million years until they encountered these modern humans 300 ky ago. Reich does not say who they were. Were they Homo ergaster or the primitive Homo naledi. Archaic admixture is something that easily explains the "diversity" of Africans vs. non-Africans.
Reich points out that the archaic Europeans were more similar to modern humans: "In Europe, the expansion of this population [modern humans] led to large-scale incorporation of local archaic genes because barriers to producing viable offspring were few, giving rise to Neandertals who ultimately harbored 3-7% ancestry from the expanding early modern human lineage."
But the archaics in Africa were really different: "In Africa, the mixture was with a more divergent lineage, which meant that there was less permeability of the expanding population to admixture with the local archaic group. Thus, the final population which became our own ancestors had a much higher proportion of ancestry from the expanding early modern human lineage."
The Levallois tools
Reich refloats a suggestion first published twentynine years ago by Rob Foley and Marta Lahr in 1997, the "Mode 3 hypothesis". They noticed that around 300,000 years ago a different stone knapping technique appeared, called Levallois. It involves more brainpower because the toolmaker has to work a stone core, in what are known as "prepared core" techniques, shaping the core to prepare it for the flakes that will later be struck from it. This "planning" and foreknowledge of the outcome requires a higher level of cognition than the older Acheulean (Mode 2) or primitive Oldowan (Mode 1) stone knapping.
Reich believes that "Levallois points" are the archaeological proof for his hypothesis. The timing is closer to 400,000 years ago: "...The genetically inferred expansion follows the time when a tool production technique (Levallois points) based on prepared stone cores spread across a wide area of Africa where it was used by early modern humans (known there as the Middle Stone Age and starting by at least 400 ka), and to the Middle East and Europe where it was used by Neandertals (known there as the Middle Paleolithic, starting by at least 480-300 ka)."
It links Neanderthals and Africans during the Middle Stone Age. Notice that the European tools are older than the African ones. Reich adds that the Denisovans in the Far East did not use this technique at such an eraly date: "There is evidence that these technologies were used much less intensively or not at all in East Asia where the closest cousins of early modern humans and Neandertals were Denisovans. In China, the sole strong claim of Levallois in the Middle Paleolithic is at the site of Guanyindong Cave dating to ∼170-80 ka, but this is not a confident inference as another study refutes this interpretation. Levallois has been documented in the Altai Mountains, but this region was proximate to West Eurasia and the technology could have spread from there through contact with Neandertal populations which are well-documented in the Altai. Similarly, evidence of Levallois in India ∼250-200 ka could have been spread by modern human populations from the Near East"
So he also suggests that modern humans were present in India and the Near East, 250,000 to 200,000 years ago. This is far older than the 60 ky suggested by the current version of the Out Of Africa Theory.
PRDM9 gene
Reich also mentions some genetic proof, the PRDM9 gene (that is a link to my post on it). Reich interprets the three main variants of this gene originated over 300 ky ago, and that one of them not found in Denisovans or Neanderthals but present in modern humans, came from archaic Africans. The second lineage is found in Denisovans and Neanderthals but not in modern Africans and is a signal of the archaic Eurasians. The third one "—showing evidence of activity of the “PRDM9-A” allele, which Denisovans lack— is the expanding early modern human lineage represented in admixed form in Neandertals and modern humans living today, but not in Denisovans: a successful early modern human population."
Comments
This is a shift in the simple OOA theory. It implies that modern humans (very likely from the Levant) expanded into Europe, met the archaic population living there, and gradually, as it moved across the continent admixed. The Neanderthal (and Denisovans) that resulted from this blend, "retain[ed] early modern human mtDNA and Y chromosomes while having most of the rest of their genome replaced by archaic genes."
Another group of modern humans from the Levant moved into Africa where our ancestors, "the ancestors of living humans" rose as the outcome of admixture with very ancient archaic hominins lifing in Africa.
It sounds compelling. But, there is only so much that can be inferred from modern genes (the samples taken from modern humans), and old, ancient DNA is lacking in Africa. We have very few samples from Eurasia, and none from archaics. So, further research is needed, and more ancient DNA from Africa, as well as Southern and Southeastern Asia.
But, there are some unanswered questions. Why would such an advanced group of early modern humans, living in a wide territorial range (Morocco to Iran, to Georgia, Iraq, Jordania, Israel, Egypt, etc) die out completely and be replaced by a more recent group trekking out of deep Africa 60,000 years ago? Who were the superarchaics living in Africa 300 kya? Where did Reich get the evidence for this Soutwestern Eurasian territorial distribution? How did the early modern humans originate? (from erectus?). The role of Denisovans (we still don't know much about them)?
Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall ©
No comments:
Post a Comment