Neanderthals actually came from Human Beings! (March 2026 paper says)

A very interesting suggestion was prepublished on March 13 in Biorxiv by David Reich, 2026, it is work in progress, and a model, but its title tells it all: Hypothesis: A modern human range expansion ~300,000 years ago explains Neandertal origins.

Trying to explain why the split date between the human lineage and Neanderthals differs when you consider nuclear DNA (765-550 kya) or mtDNA (365-400 kya), or why the original Y chromosome of Neanderthals appears to have vanished, and what we have found is so similar to ours, and that their mtDNA is remarkably similar to ours, Reich suggests that they are a population that arose from modern humans introgression with archaics in Europe. This also explains some incongruent dates and other oddities found in the Atapuerca Sima de los Huesos remains. Simple hypothesis that is very similar to the proposal maed by Cosimo Posth published in Nature, which I commented in a post back in 2017 (An even older Out of Africa event (270kya)!!). Posth suggested that African inflow was "responsible for providing the mtDNA to the Late Pleistocene Neanderthals might have been an even earlier Middle Pleistocene gene flow from Africa, occurring in a time interval that we date between 413 and 268 ka... The temporal corridor for this introgression event between 460 ka and 219 ka is compatible with the evidence of archaeological similarities between Africa and western Eurasia during the Lower to Middle Paleolithic transition39 and potentially may explain the dissimilarities in Middle Paleolithic industries between eastern and western Eurasia. Environmental changes across this time span might have facilitated a hominin expansion out of Africa and potentially spread cultural innovations such as the Levallois technology into Eurasia." Reich developed the concept. Below is the Abstract of Reich's paper

"Abstract.
This paper demonstrates the feasibility of the hypothesis that Neandertals formed when a population using recently developed Levallois stone tool technology expanded between 400-250 thousand years ago (ka). In Europe, their range expansion into an area with Sima de los Huesos-like people led to massive introgression of local archaic genes producing a population with around 95% archaic ancestry (Neandertals); if this range expansion was sex-biased it would provide a simple explanation for why Neandertals retain modern human lineage Y chromosomes or mitochondrial DNA. In Africa, interbreeding with local archaic humans led to more modest archaic admixture and the deep substructure detected in all modern humans today. This proposal explains four previously perplexing similarities of modern humans and Neandertals—sharing of mitochondrial DNA, Y chromosomes, Levallois tools, and 300-200 ka date of formation by mixture—even while Neandertals and Denisovans cluster genome-wide."

This is the paper: Hypothesis: A modern human range expansion ~300,000 years ago explains Neandertal origins David Reich. bioRxiv 2026.03.11.711219; doi: https://doi.org/10.64898/2026.03.11.711219.

This paper is interesting because it also mentions humans mixing with archaics inside of Africa, a source of diversity:

"... ancestors of all modern humans including sub-Saharan Africans were deeply substructured, due to the coming together a few hundred thousand years ago of lineages that began diverging a million or more years ago. For example, ref. 16 models modern human ancestry as largely derived from a mixture of about 80% from a lineage that was most closely related to Neandertals and Denisovans, and 20% from a lineage that diverged from it around 1.5 million years ago, with the two coming together around 300 ka. The remixture is estimated to date to around the same time as the genetically inferred interbreeding of modern humans and archaic humans in the ancestors of Neandertals 300-200 ka. This raises the possibility that these mixtures in Europe and Africa had related causes: a range expansion of a successful population interbreeding with local archaic groups. In Europe, there was massive introgression of local genes because barriers to producing viable offspring were few. In Africa, the mixture was with a more divergent archaic lineage, result in a lower γ (cross-group interbreeding rate), and less introgression..."

This is the reference "ref. 16" cited above: Cousins T, Scally A, Durbin R, (2025) A structured coalescent model reveals deep ancestral structure shared by all modern humans. Nat Genet 57, 856–864.

Comments

I am surprised at the different conclusions that the same datasets of human genes and fossils produce (some are mutually exclusive): humans and Neanderthals are the same, humans and Neanderths split after the Denisovans split, Denisovans and humans split after the Neanderthal split, dates that range from 500 to over 1 million years, introgressions all over (Denisovan to Neanderthal to Human, Human to Neanderthal, Denisovan to Human, one or more lineages of superarchaics introgressing into different hominins). Surely they can't all be right.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall © 

Neanderthal males mated with Human females (says study published in Science)

An article published in the latest issue of Science (Alexander Platt et al., Interbreeding between Neanderthals and modern humans was strongly sex biased. Science 391, 922-925 (2026). DOI:10.1126/science.aea6774) suggests that male Neanderthals had a soft spot for female Anatomically Modern Humans (AMH), or that AMH women chose male Neanderthals as mates, or both.

Thos of us who trace our ancestry to a non-Sub-Saharan African ancestor, carry snips of Neanderthal DNA in our chromosomes. These come from an admixture (mating) episode that took place some 45,000 to 49,000 years ago. A few thousand years later, the Neanderthals vanished and our human ancestors replaced them. But these Neanderthal genes are not uniformly distributed across our chromosomes. Why?

The Neander men mated with Human women!

The authors came to this conclusion (human women mating with Neanderhtal men) after looking at the distribution of Neanderthal alleles in our human genome. Although our ancestors mated with Neanderthals, and all humans living outside of Sub-Saharan Africa carry Neanderthal genes, there are vast swaths of autosomal genes in our 22 chromosomes that are devoid of Neanderthal alleles. An interesting anomaly is that the X chromosome us even more depleted of Neanderthal alleles (we carry another four chromosomes, either two "X" or an "X" and a "Y" if we are women or men, respectively). Why would the "X" chromosomes carry less alleles than the others? Well, this paper says that it reflects how Neanderthals contributed to our ancestry, the X chromosomes don't show Neanderthal ancestry because they are mainly human ones, mostly from human women and much less from Neanderthal women. Women contribute their X to all offspring, men do so only to their daughters, as their sons carry their Y chromosome. There could also be another factor that added to this distortion, natural selection that selected against the Neanderthal alleles.

The paper begins by stating in its Abstract that "By observing a 62% relative excess of AMH ancestry in Neanderthal X chromosomes, we characterized the interbreeding between the two groups as predominantly male Neanderthals with female AMHs" They suggest two explanations for this skew, to explain the "Neanderthal deserts across the modern human X chromosomes: (i) The lack of Neanderthal loci amongst the X chromosomes in the mode, or (ii) the contribution of Neanderthal X chromosomes was reduced from the very beginning and represents an original interbreeding that was biased toward male Neanderthals and female anatomically modern humans (AMHs)."

To validate which hypothesis is correct, they looked back, at the first admixture between AMH and Neanderthals, that took place 250 ky ago, and observed the fate of Neanderthal alleles in their offspring and applied these conclusions to the more recent admixture that ocurred 50 kya.

So they analyzed the genes of Neanderthals who lived after the AMH-Neanderthal admixture, including the Altai Neanderthal (122 kya), the two females from Chagyrskaya (80 kya) and and Vindija (52 kya). The authors concluded "that the lack of Neanderthal alleles in the modern human gene pool is not simply the result of excess incompatibility loci on the X chromosome". They also discarded genetic drift due to a small population size for the Neanderthals. Regarding the effects of Natural Selection, they found that "the Neanderthal X chromosomes did not suffer from sufficient mutational load to cause them to be generally deleterious compared with AMH X chromosomes." So evene if natural selection acted, it "was not likely sufficient to drive the broad lack of Neanderthal ancestry in the modern human X chromosome gene pool"

Caveman Courtship

Buster Keaton, Margaret Leahy and Wallace Beery in a scene from The Three Ages, 1923 . Source

Then they looked at dispersals and relocations between human and Neanderthal populations due to pair-coupling and mating (where female AMHs relocate into their Neanderthal partner's community) and modeled different scenarios. For instance, if all the AMH women of an exclusive all-female migration, mated with Neanderthal men, the excess ratio of AMH ancestry in the X chromosome of the hybrid offspring would be 1.33 (or +33%), but they observe a 1.62 excess ratio (+62%). One also has to consider the opposite effect of AMH males mating with Neanderthal women, which would lower the AMH presence in the X chromosomes of their hybrid offspring.

Since this can't raise the proportion of AMH presence in X chromosomes, they reasoned that the alternative was "mating preference" and describe it as follows: "the patterns that we observed in AMH-Neanderthal divergence and hybridization follow traditional processes of speciation and were likely colored by a persistent preference for pairings between males of predominantly Neanderthal ancestry and females of predominantly AMH ancestry over the reverse. The bias that we inferred seems to have remained consistent across admixture events separated by 200,000 years. Although we do not know what drove the biases in either event, the potential for preferences in mate choice to persist across time and space have been documented in both human and animal studies." So Neanderthal men liked AMH women more (or viceversa, or both!)

Simple one step mating Neanderthal man, and AMH woman. © 2026, Austin Whittall

The same issue of Science has a commentary on this paper (online here) and its title is suggestive: "Surprising partner preference found in matings between Neanderthals and modern humans. Male Neanderthals tended to pair up with female modern humans, but whether intercourse was consensual is unclear." It describes the article and interviews some scholars about it, concluding that "The mating bias Tishkoff and her co-authors have uncovered reflects something about the cultures and social behaviors of both species, she says. The team did not venture to guess whether the intercourse was consensual or coerced. But to Steven Churchill, a Duke University paleoanthropologist who was not involved with the research, the finding implies aggression. If males from one species monopolized females from the other, he says, “it’s hard to reconcile that with anything but a competitive, unfriendly interaction.”"

Closing Comments

I don't see why these interactions had to be violent, but given apes and humans tendency to be sexual, and aggressive it is an option, or perhaps wokism trying to explain ancient mating behavior.

Back in September 2011, I posted on the admixture of Neanderthal males and Human females and tried to answer the question of why there is no Neanderthal (NH) mtDNA in Homo sapiens (HS) (there should be if a matrilineal lineage had survived until now, with an original Neanderthal female passing her mtDNA across the generations until the present). I reasoned that: "Since nowadays there is no Neanderthal mtDNA in HS, we can conclude that mating between HS men and NH women (was as limited) or, if more frequent, it did not lead to a continuous lineage of hybrid N/HS women... if Neanderthal men got human women pregnant, they would not pass on any NH mtDNA (the children would have their human mom’s mtDNA). But, the Neander-Dad would pass on his nuclear DNA . So, Man (NH) and Woman (HS) would be a viable route to get Neanderthal DNA into our Homo sapiens cells. This explains why we have Neander DNA (autosome chromosomes)."

However, my reasoning did not lead to a higher prevalence of Human X chromosomes in the case of Neander-Human matings! I believe thtat this is so because I took into account Haldane's Law of sterile male offspring. As you can see in the image further up, if you eliminate the boys, who each carry an X in their XY sexual chromosomes, the two girls, would make it a 50-50 proportion as each carry a Neanderthal X and a Human X. In the same ratio! Maybe Haldane's Law does not apply?

Haldane's Law or Rule "JBS Haldane noted that when hybrid crosses affect one sex more significantly than the other, it is almost always the heterogametic sex that is so affected1. Thus, the risk is greatest for XY male hybrids in mammals... A century of observations has confirmed this rule." (Source).

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall © 

HST and Scladina Neanderthals

A A recent paper by Stephane Peyregne et al., (Nuclear DNA from two early Neandertals reveals 80,000 years of genetic continuity in Europe, Science Advances 26 Jun 2019: Vol. 5, no. 6, eaaw5873 DOI: 10.1126/sciadv.aaw5873) looked into the mitochondrial DNA (mtDNA) of some ancient European remains and compared them to that of modern humans, Neanderthals and Denisovans.

What they found is indeed interesting, and unexpected.

The team sampled the remains of two Neanderthal people, which lived roughly at the same time (some 125,000 years ago), relatively close to each other in Western Europe: a male femur (thigh bone) discovered in the Hohlenstein-Stadel Cave, Germany, back in 1937 -this sample was named HST. They also analyzed a jaw bone belonging to a girl found in 1993 in Scladina, Belgium.

The mtDNA of the Scladina girl and the HST man, both from Western Europe, were most similar to the mtDNA of the Altai Neandertal (from the Altai region in Asia), 3,300 miles (5.300 km) west of Scladina and Hohlenstein-Stadel.

Their mtDNA was quite different from the mtDNA of later European Neanderthals that lived in the same region 80,000 years later.

HST and its unique mtDNA

The HST an carried mtDNA that was very different from that of all other Neanderthals, it had more than 70 mutations that distinguish it from the others' mtDNA. The bone was dated to approximately 124 kya. (62 to 183 kya), but its mtDNA split from that of other humans 270 kya.

The girl's remains are of a similar age: 127 kya (95 to 173 kya) but her mtDNA was more similar to that of an Asian Altai Neanderthal.

In fact both Scladina and the Altai Neanderthal grouped together in a branch of their own, with HST at the root and all other later Neanderthals on a separate branch.

The image below shows the branch that groups the Scladina girl with Atai Neanderthals and the HST Branch (inside the red square). As you can see, they are quite differentiated from that of all the other Neanderthals and Modern Humans (we are shown on the upper part of the diagram).

MtDNA of Neanderthals, Sima de los Huesos, Denisovan and Modern Humans

The fact that these three older Neanderthals are grouped together (see red square in image above) means that they share a common lineage of mtDNA; they all lived more or less at the same time (some 125 kya) and spanned a wide geographic area from the North Sea to the Altai in Siberia.

All more recent Neanderthals who lived roughly 40,000 years ago (green square in the image above) shared a common ancestor who lived some 97 kya, and belong to a branch that diverges from that of these three older Neanderthals.

These "modern" Neanderthals' mtDNA is derived from that of the "older" group.

The interesting part is that the Denisova Neanderthal (see "Denisova 11" in the image) which lived 90 kya in the Denisova cave in Central Asia, and is a hybrid of Denisovan father and a Neanderthal mother, has mtDNA which is closer to the more recent Neanderthals of Western Europe than to the Altai Neanderthal that lived in that same Denisova cave! 120,000 years ago.

This means that the ancient mtDNA of Altai Neanderthals was replaced by the "new" mtDNA shared by Denisova 11 and all other modern Neanderthals, so these later western European Neanderthals migrated east into Siberia and repopulated the Altai.

What about the Nuclear DNA?

The team looked into the nuclear or autosomal DNA of both Scladina and HST specimens and compared them with that of other Neanderthals.

They found that from a nuclear DNA point of view HST and Scladina were "more closely related to Vindija than they are to the Altai Neandertal". Vindija is a cave in Northern Croatia.

We see that all Neanderthals, old and recent share a common root for their nuclear DNA, but there are two branches: one with the Altai Neanderthal, and the other with all the other Neanderthals.

So it may be reasonable to suppose that all known Neanderthals (old and recent) share a common origin, and that it split as they migrated into Western Europe (HST and Scladina) and Siberia (Altain Neanderthals), this explains their branching.

Regarding the Atai Neanderthal, (see Prüfer K, Racimo F, Patterson N, et al. The complete genome sequence of a Neanderthal from the Altai Mountains, Nature. 2014;505(7481):43–49. doi:10.1038/nature12886) it was found to be (see Figure 2b in that paper) on the most diverged and basal branch within Neanderthal's nuclear DNA and therefore furthest away from the Vindjia specimens).

See image below, which I adapted from (here) and Fig. 2 of Peyregne et al.; it depicts the Nuclear DNA branching.

So we can imagine a very early migration of Neanderthals into Siberia (ancestral to Altai Neanderthal) who did not leave descendants.

The Western Neanderthal population (which included HST and Scladina) had settled Europe 125 kya and its descendants later migrated across Eastern Europe, entered Asia and settled in the Altai region replacing this eastern population in Asia.

The very odd HST mtDNA

The very divergent mtDNA carried by HST split from that of all other Neanderthals some 270,000 years ago. This is far older than expected by the team (they'd estimated less than 150 kya).

And they believe that this is due to the fact that "HST carries some ancestry from a genetically distant population.".

They propose two scenarios:

1. "Admixture between Neandertals and ancestors or relatives of modern humans could explain the origin of this later Neandertal mtDNA... If several mtDNAs were introduced into the Neandertal population by such a putative gene flow, then the deeply divergent mtDNA in HST may represent the remnants of the mitochondrial diversity of this introgressing population... This would imply that this admixture into Neandertals occurred later than the previously suggested lower boundary of 270 ka ago".
2. "An alternative source for the deeply divergent mtDNA in HST could be an isolated Neandertal population, for example, a population that separated from other Neandertals before the glacial period preceding HST and Scladina (~130 to 190 ka ago...). Such an isolated population may have preserved the mtDNA that was later re-introduced during a warmer period between 115 and 130 ka ago (the “Eemian” period) when these populations met again and gene flow resumed."

Discussion

I ask: Can we reasonably expect a group to remain in isolation for 15,000 to 75,000 years and maintain their mtDNA without mutations? This "isolated group"notion is identical to the Beringian Standstill Hypothesis which states that the humans who would people America remained isolated in Beringia for tens of thousands of years.

But the Beringian mutated while the isolated Neanderthals did not! This is weird, same situation and two different outcomes:

The Beringians suffered mutations that gave their descent, the modern Native Americans a distinctive mtDNA that is not found in Asia is said to have arisen during the "standstill": after their ancestors left Asia, but before they dispersed into the Americas.

Yet the isolated ancestors of the Neanderthals retained their original mtDNA without anyn mutations.

So in one case it is mtDNA "stasis" and in another "mutation". You can't have it both ways. One or other or perhaps even both theories are wrong.

In this context, the admixture theory seems reasonable, but why should we have to assume admixture? Let's read it in the paper's words:

"It seems unexpected that HST carries an mtDNA lineage that diverged ~270 ka ago from other mtDNAs, given the recent population split times from the Vindija ancestors and the low levels of genetic diversity in the nuclear genomes of Neandertals".

In other words, as their nuclear genome is very similar to that of the Vindija Neanderthals, who lived 80 ky later than HST, their mtDNA can't be 270 ky old.

They add:

"An explanation could be related to a replacement of mtDNAs in Neandertals that has been suggested to explain the discrepancy between the mtDNA divergence time (<470 ka ago) and the population split times based on nuclear DNA (>520 ka ago) between modern humans and Neandertals.
The Sima de los Huesos hominins, and perhaps other early Neandertals, carried mtDNAs that shared a common ancestor with Denisovan mtDNAs more recently than with those of modern humans, whereas later Neandertals carried mtDNAs that shared a more recent common ancestor with the mtDNAs of modern humans.
Admixture between Neandertals and ancestors or relatives of modern humans could explain the origin of this later Neandertal mtDNA".

We see that once again there is a discrepancy between mtDNA and nuclear DNA divergence dates, you'd expect both to be the same age. In this case it is 470 ky vs. 520 ky.

In a previous post on this subject (Sima de los huesos is now.... closer to Neanderthals than Denisovans!) I gave an explanation for this conundrum as follows:

The common mtDNA shared by Denisovans and Sima de los Huesos but not the nuclear DNA could be explained as follows:

• A native archaic population lives in Eurasia (descendants of H. erectus?) with its specific autosomal DNA and mtDNA; they are the ancestors of Denisovans and a pre-Sima de los Huesos people.
• A later wave of proto-Neandertal reach Europe, they are more successful and breed with the native women (kill the men and keep the women) of the native pre-Sima de los Huesos stock.

The original archaic mtDNA is preserved in their offspring -since it is transmitted by the mothers to their children-, but the nuclear DNA is now admixed with that of the proto-Neandertals.

After many generations we have a European lineage with mtDNA similar to the original ancient stock (Homo erectus?) and therefore shared with Denisovans, but a nuclear DNA which will be more like that of Neanderthals which were formed by this admixture.

A similar event must have taken place with the Neanderthals.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2019 by Austin Whittall ©