Unless you’ve been sleeping under a rock, a new paper in Nature establishes that Homo erectus was present in Southeast Asia quite late in the Paleolithic. Last appearance of Homo erectus at Ngandong, Java, 117,000–108,000 years ago:
This dated sedimentary and taphonomic framework for the Ngan-dong bone bed does not support an overlap between modern humans and H. erectus in this region…Instead, the Ngandong fauna in facies A (140 ±24ka) pre-dates the rainforest-associated site of Punung (between 128 ±15ka and 118 ±3ka)…which agrees with the proposed biostratigraphical sequence of Java based on the palaeoenvironmental and associated faunal changes
Paleoanthropologists that I follow on Twitter seem to find the dating creditable. I can’t evaluate it personally, so I’ll take that as a given.
From what I can see the authors seem to be presenting a hypothesis where environmental shocks and decline led to the local extinction of the “erectus” lineages before the arrival of modern humans, perhaps 60 to 80 thousand years ago (depending on which archaeological dates you accept). It does seem likely though that Denisovans were still present when modern humans arrived, going by the latest genetic evidence, while best dating of the “hobbits” of Flores suggests they went extinct only 60,000 years ago.
First, I would bet that various hominin groups were around after their last presence in the archaeological record. I now think there’s enough circumstantial evidence to suggest “modern” African-related/derived humans were present in and around southern and eastern Asia around ~100,000 years ago. There is evidence of modern humans in Sumatra ~70,000 years ago. Also, there are signs of gene flow from modern humans into Neanderthals hundreds of thousands of years ago.
Flores, various Denisovans, early modern humans, and also now the hominins in the Philippines, point to a high degree of speciosity in Southeast Asia. This is not terribly surprising. Southeast Asia is a relatively “protected” area of Eurasia, and so can serve as a refuge during inclement periods. And, during the Pleistocene, its surface was much more extensive. Sundaland covered the western third of modern Indonesia. Many of the prime habits are almost certainly underwater today.
To step back, we also have to note that it seems the overwhelming proportion of ancestry in modern humans outside of Africa dates to an expansion from a very small group that began 50-60,000 years ago. We have some evidence, obviously, of uptake of Neanderthal and Denisovan ancestry. But no strong evidence of “first wave” modern human ancestry. I think part of this is simply the reality that if there was mixture at low levels with earlier groups of modern humans in places like Southeast Asia one may not have the power to detect it well because the two lineages are not particularly distinct, as is the case with Neanderthals/Denisovans vs. modern humans.
I put “erectus” in quotations because what do we even mean by this? Was “erectus” really a coherent species for a million years in Southeast Asia? I doubt it. It’s more of a catchall and placeholder from what I can tell. Before the expansion of 50-60,000 years ago, the Eurasian landscape was much more diverse in terms of humans. Neanderthals seem to be relatively homogeneous, but Denisovans not so much, and I think the same would apply to various “erectus” groups. I bet that once some ancient DNA comes back from China we’ll see more than just Denisovans ~100,000 years ago.
Homo erectus seems to have been one rather homogeneous species when it expanded from its homeland, but it diversified pretty fast and in a way all humans might be considered descendents from erectus.
From the general population branches split off, became first regional races, then species, like its the usual way in all animals.
Denisovans seem to be the more developed forms from East Asian Homo erectus, probably with gene flow from more developed neighbours like Neandertals and archaic sapiens involved to keep them compatible with moderns?
Otherwise “Homo erectus” can just mean more archaic forms (developmental stage) which didnt follow the path of further hominisation, which were cut off from more developed impulses and so archaic reproduction with sapiens was either unwanted or even impossible.
Looking at the world map, most expansive species have developmental and demographic centers. For fully modern humans the earlist center is still unknown, but should be between North Africa-East Africa and South West Asia.
Modern centers are those which are vital for the modern populations and major races (like Eastern Europe-West Asia, Northern East Asia and Western Africa). South East Asia and Australo-Melanesia were always the periphery of modern human developments. The main difference of Sundaland to America was it was easier to access, so even big apes and ALL human forms could make it to SEA. They obviously disappeared in a row in order of their first appearance, once the next human developments from the centers came in. If Orang Utans and the Flores species were able to survive, a higher human form like erectus is even more likely to make it.
Obviously it was the newcomers which caused their end, one way or another. Yet one should look at the genomes first, to determine the specimens real relationship to “Denisovans”.
My understanding is per what Reich and other adna experts think, apparently Denisovans split from a Neanderthal+Deni (main trunk Eurasian?) about circa 400kya. Too young for Erectus (common ancestor at 400kya can’t be morphologically like Erectus, because apparently Sima De Los Huersos ancient dna suggests they are close to common ancestor? Mt and nuclear dna from SDLH shows similarities to both Neanderthal and Denisovan). Nean+Deni have more recent common ancestor with H Sap. Though Erectus in Asia may be “super archaic” that also contributes small admix edge to Deni.
See (http://dispatchesfromturtleisland.blogspot.com/2019/07/dilute-super-archaic-hominin-ancestry.html) for one version of graph.
Denisovans probably substructured quite deep, almost as deep a Denisovan+Neanderthal split – http://www.sci-news.com/genetics/two-denisovan-lineages-modern-papuan-genomes-07086.html (350kya vs 400kya?)
Re; blogpost, interesting comment re the catchall of “Homo Erectus”. There looks to be some discussion in a paper of shape shifts in the late Ngandong samples here – https://www.jstage.jst.go.jp/article/ase/125/2/125_170413/_html/-char/en. Looks like volume increase and some partially unrelated shift towards relatively taller, frontally wider post the orbits skull. Although clearly not as dramatic volume increase, shape change, in H. Sap, etc.
@Matt: Some arguments why Denisovans might be just “admixed Homo erectus”:
– plenty of remains of Neandertals have been found, but none which could properly represent “Denisovans”. What has been presented fits into the scheme of more developed and admixed Homo erectus (teeth!).
– the distance you mentioned would be drastically reduced by admixture with Neandertals and archaic sapiens, which I proposed
– the split from sapiens is much older anyway, and this is key.
The more archaic South East Asian erectus might be just more diverged and not admixed. But to prove this, you need their DNA.
I would bet they are closest to the unmixed (by Neandertals and sapiens) “Denisovan like”.
Its up to future samples.
The genetics so far suggests Denisovans have about 1% ancestry from super-archaic (https://www.biorxiv.org/content/10.1101/687368v1.full – “We also identify 1% of the Denisovan genome which was likely introgressed from an unsequenced hominin ancestor”), and the 99% bulk of ancestry from a shared population with ancestors of Neanderthals around 400kya. That’s where the estimates are. Autosome of Denisovans and Neanderthals very much a clade relative to AMH outgroup (accounting for admixture in recent AMH groups and some, older, the other way); not splitting earlier or later. That is most parsimoniously explained with being about 99% descended from the same common ancestor which diverged from AMH’s ancestor much later than Asian Erectus (rather than a load of complex admixtures that somehow arrive at this same state of being almost perfectly a clade).
There are no crania in Asia that are clearly Denisovan and not Erectus, but in the main, other than the late Indonesian survivors, there are no crania fossils which postdate the estimated Heidelbergensis (Neanderthal ancestor) expansion at around 400kya at all – https://en.wikipedia.org/wiki/List_of_human_evolution_fossils. The fossils that do show up that postdate this boundary are not clearly descended from earlier Erectus to the exclusion of resemblences to Neanderthal, e.g. – https://en.wikipedia.org/wiki/Jinniushan – “The Jinniushan specimen’s estimated cranial capacity is 1,330 cm3 (81 cu in). The encephalization quotient (EQ) is estimated to be around 4.150. Both are typical of the rapidly increasing brain capacity and EQ found in other specimens from the Middle Pleistocene …. The Jinniushan specimen belongs to an archaic human with mixed Homo erectus and Homo sapiens features.” (note mixed features, does not imply a mixed ancestry). Note position of Jinnushan on shape PCA compared against Early Pleistocene- https://core.ac.uk/download/pdf/35279280.pdf (Another fossil, HLD6 treated here – https://www.pnas.org/content/116/20/9820)
I don’t see from all this that there is a strong basis to argue that Denisovans must nevertheless be descended from the early dispersal of Erectus into Asia 1000-2000 kya. The genetics don’t seem to support it, and there’s no clear sign of continuity in cranial series either. Don’t get “sunk costs fallacy” about this one. Patterns of repeated expansions and little continuity over hundreds of thousands of years are to be expected.
Closest actual morphological proxy we have for “Denisovans” so far is the Xiahe Mandible – https://www.nature.com/articles/s41586-019-1139-x – “Here we report a Denisovan mandible, identified by ancient protein analysis, found on the Tibetan Plateau in Baishiya Karst Cave, Xiahe, Gansu, China.” (assuming this is correctly identified by protein analysis)
Dental arch separates from Erectus, while tooth root and shape of mandibular body less so – https://imgur.com/a/lMgzagf . But then there is a lot of within species variation on all these traits (e.g. Early AMH vs modern and Upper Paleolithic, etc)
More info from Hawks – https://twitter.com/johnhawks/status/1123650680739254273
Question, but weren’t sea levels much higher during the Eemian? Surely this would mean isolated island populations, not a broad Sunda habitat?
On the general topic of Southeast Asia being plentiful in genus Homo species, that does sort of raise the question about one proposed advantage of African ancestors to H Sap.
Basically, it has been proposed that Africa preserved a larger population size (by Stringer in multi-regions but by others presumably in African subregions), and that this leads -> more beneficial mutations or higher fitness -> eventual expansion of H Sap over low pop size groups like Neanderthals. (Cochran quotes, critically, a couple of these articles in his blogpost back from 2015 “Degenerate Neanderthals” – “The first paper concludes that Neanderthals must have had much lower fitness than AMH: They say ‘Under an additive model, a recessive model, or anything in between, the severe reduction in fitness of Neanderthals would have doomed them to quick extinction if they had been competing for the same niche with humans under conditions of reproductive isolation.'”).
So one thing that surprised me, in this context, was that the “DenNy” 1G hybrid of Altai Neanderthal and Denisovan populations seemed to have been about as heterozygous as present day Africa! See – https://www.nature.com/articles/s41586-018-0455-x
That being the case, I’d wonder, if heterozygosity is a big fitness advantage, you firstly don’t get DenNy type populations expanding through Eurasia before AMH, and secondly why massive hybridisation, large populations, adaptive evolution never happened in SE Asia. Bad luck? On the face of it seems to revise down our reasons to guess that heterozygosity->fitness mattered in the OoA expansion (if we have good reason to think that comparably heterozygous populations must have come about through hybridisation reasonably frequently within Eurasia).
(And note there are some ideas that African heterozygosity today benefits at least slightly from enrichment by “basal African” after the OoA migration – https://genomebiology.biomedcentral.com/articles/10.1186/s13059-019-1684-5).
@Matt: I didn’t suggest that all Asian Homo erectus forms survived and developed into the “Denisovans” we see in the genetic record so far, rather that from the general Homo erectus layers in Eurasia different Hominids evolved, like Neandertals and “Denisovans”, with the latter being close-identical to the more evolved Asian Homo erectus forms.
I will now quote from Reich what I find interesting for the discussion:
“Recently, we used a DNA capture approach10 in combination with high-throughput sequencing to determine a complete mtDNA genome from the Denisova phalanx. Surprisingly, this mtDNA diverged from the common lineage leading to modern human and Neanderthal mtDNAs about one million years ago19, that is, about twice as far back in time as the divergence between Neanderthal and modern human mtDNAs.”
This is just mtDNA, but even without assuming more recent admixture events, the paper concludes:
“Assuming 6.5 million years for human–chimpanzee divergence, this implies that DNA sequences of Neanderthals and the Denisova individual diverged on average 640,000 years ago, and from present-day Africans 804,000 years ago.”
https://www.nature.com/articles/nature09710
From the paper on the mandible:
“Xiahe plots at the edge of the H. erectus distribution and within the range of Middle Pleistocene Homo.”
https://www.nature.com/articles/s41586-019-1139-x
There is no contradition to the assumption that “Denisovans” were just a more evolved branch of Homo erectus in Asia. Not as distinct, as derived as Neandertals, surely not as much as AMH which made a leap forward in Hominisation, but still in the range of H. erectus.
I agree with Hawks on this comment:
“The Xiahe specimen predates the Denisova discoveries in both geological age and discovery time. Neither matters formally to taxonomy, which is just a race to publication. But do we really have a reason to keep “Denisovans” as the name as more fossil discoveries are made…”
and this one:
“A slower mutation rate might bring the most recent specimens of Homo erectus into the temporal range of the Denisovan population, by elevating the time of divergence of Denisovans, Neandertals and contemporary African peoples. Whole-genome sequencing of human parent-offspring pairs, as well as resequencing of more limited regions of the genome, has suggested a slower rate of substitutions Hawks:2012, Scally:Durbin:2012. This would be consistent with a much earlier diversification of Denisovan and Neandertal genomes, making it possible that they came from an early Middle Pleistocene adaptive radiation.”
But this is not just debatable, it is now outright wrong, proven by the very find with which the thread started, I didn’t agree with that assumption before, but now its done by a broad consensus anyway:
“The Denisovans were too closely related to living humans to represent Homo erectus, as it is currently understood. Homo erectus occurred widely in Asia, including China and Java, and Africa during the span from 1.95 million to 750,000 years ago. In China and Java, fossils attributed to Homo erectus persisted until 200,000 years ago. There is no unequivocal fossil of Homo erectus after 200,000 years ago.”
http://johnhawks.net/research/denisova-iuaes-2012.html
Even without additional gene flow from the ancestors of H. sapiens, this means we are in the range of Homo erectus proper. The best scenario is just that Homo erectus spread in Eurasia, while a major population stayed behing in Northern-Eastern Africa-SW Asia and evolved to Homo sapiens, with gene flow taking place, but being rather limited. Homo sapiens formed a metapopulation of its own, the largest and most dynamic one.
The Asian Homo erectus which had contacts with Neandertals evolved on too, with “Denisovans” being most likely just the closest and most evolved branch.
Obviously a lot is about terminology, because where do you begin with Homo erectus and where let you end it? I think there is no clear borderline, even less so than with Neandertals, and much less so than with sapiens, to draw from the “general Homo erectus” to “Denisovans”. But obviously it can be drawn, but that’s almost more a race (of H. erectus) than species even in comparison.
Yet the real relationship to the more archaic, “classic” erectus forms can only be determined by genetic testing.
“Denisovans” was just the name used because we did not know anything about the Hominid from which the finger bone came from. But we had “Homo erectus” remains in every place where we now assume “Denisovan” gene flow to moderns took place. Pure chance and coincidence? A “species” which inhabited most of Eurasia, had, like you self said
“Denisovans probably substructured quite deep, almost as deep a Denisovan+Neanderthal split – http://www.sci-news.com/genetics/two-denisovan-lineages-modern-papuan-genomes-07086.html (350kya vs 400kya?)”
That’s because there was a dynamic inside of the Eurasian Homo erectus forms, from which this main branch of Neandertal-Denisovans evolved, split, and spread. But this was all within the time frame of classic Homo erectus. There was nothing else around!
Take e.g. the “Peking man” as a holotype, you can read:
“The most complete fossils, all of which were portions of the skullcap (calvariae), are:
Skull II, discovered at Locus D in 1929 but only recognized in 1930, is an adult or adolescent with a brain size of 1030 cc.
Skull III, discovered at Locus E in 1929 is an adolescent or juvenile with a brain size of 915 cc.
Skulls X, XI and XII (sometimes called LI, LII and LIII) were discovered at Locus L in 1936. They are thought to belong to an adult man, an adult woman and a young adult, with brain sizes of 1225 cc, 1015 cc and 1030 cc respectively.[10]
Skull V: two cranial fragments were discovered in 1966 which fit with (casts of) two other fragments found in 1934 and 1936 to form much of a skullcap with a brain size of 1140 cc. These pieces were found at a higher level, and appear to be more modern than the other skullcaps”
https://en.wikipedia.org/wiki/Peking_Man
What else should they be than close to “Denisovans”? Do you think there is anything else in between these and the SEA “Denisovans” which contributed to Aeta and Australo-Melanesians? A “mystery species” which slipped through the record? I don’t think there is. Denisovans are in the range of what was commonly seen as “Homo erectus” before the aDNA came in and I think that the genetic results will, eventually, come to terms with that view as well (might still prefer a new name for the branch though, but in the bigger taxonomic picture, there is no way out most likely).
If you ask 10 palaeoanthropologists about the right specimen for Denisovans, you mostly just get more evolved Homo erectus forms as the most likely candidates. Its just the assumption that they should be genetically different which led to this uncertainty. But what do we really KNOW for sure?
The crucial point is also, that typical Homo erectus specimen were defined in the past exactly by later, already more evolved forms like “Sinanthropus”, so even if there were multiple waves of Homo erectus like forms throughout Eurasia, with some more archaic (like Flores) being pushed aside and representing this elusive “1 percent species” found in Denisovans, even these later waves were seen as just (more evolved, even more typical) Homo erectus in the past. Not something else.
The question is just whether the more evolved Northern branch, which was more closely related to Neandertals (by admixture too?) moved South and replaced older layers, like that very archaic, even devolved Flores species (which relatives must have been wider spread), or we have some sort of local continuity. Obviously if the genetic estimates so far are right, its more likely there was replacement about 500.000 yBP. But let’s see what’s that all about. We really need a fully tested H. erectus specimen, better more than less. The more we have, the closer the gap between supposed “Denisovans” and Homo erectus will become, until it disappears. The very fact that Neandertals and modern humans bred with them let to the conclusion “they must be different”, but they were not – at least that’s my current position, I will change it without hesitation if the results prove the opposite.
Doesn’t seem worth it, in the context of this discussion, to use an estimate of AMH, Denisovan, Neanderthal divergence times from a 2010 paper from Reich (804,000 AMH to ND then 640,000 for N and D) when Reich himself published last year (2018) the following in “Who We Are And How We Got Here (page 87)”:
“The first revelation from the whole genome was that Neanderthals and the new humans from Denisova Cave were more closely related to each other than either was to modern humans — a different pattern from what was observed in mitochondrial DNA. We eventually estimated the separation between the Neanderthal and Denisovan ancestral populations to have occurred 470,000 to 380,000 years ago, and the separation between the common ancestral populations of both of these archaic groups and modern humans to have occurred 770,000 to 550,000 years ago.”
There’s not much point hauling out these old estimates that everyone who has read as much as “Who We Are…” already knows are outdated and are not what Reich et al currently think. Adna research is fast moving!
The rest of the post is too long – sorry I can’t respond to such a long post, and I’m not sure about what bits of it are saying. There may be some interesting points in it and I will have a look later if I get some time. Whether the ultimate origin of N+D (as a clade by 400kya) is from Asian Erectus or African Homo, I don’t know, and Reich himself seems surprisingly agnostic on it in “Who We Are…”, but if it were the case that N+D are from Asian Erectus, so must Homo Sapiens (as a clade with N+D at 660 kya) in Africa have ultimately been too (see Reich’s scenario on page 101).
The new estimates from his books are still just that, estimates, and the lower (imho more realistic) is just 34.000 younger than the old estimate, that is nothing. There is no real change in these numbers, he just added an unrealistic higher end.
I can sum the rest up for you, with details you can prove for yourself in the longer post:
We have finds like Peking man with a quasi-modern (lower range) cranial capacity and in the central place and time when Denisovans must have been around there. Peking man was the holotype for Homo erectus for quite some time. The earlist descriptions brought Peking man specimen even close to Neandertals by the way (!), so that is no contradiction to anything new aDNA could tell us.
If Hawks said there were no unambiguous H. erectus finds around after 200.000 BP, that’s a question of how you define it in the first place, but there is no clear cut, as the mandible from Xiahe is proving actually. And we now even have classic H. erectus from the later time. There is just no gap in any respect between what was commonly defined as H. erectus and what is supposed to be Denisovan. Unless you have a very specific and narrow definition. But I predict that Peking man, if tested, should be very close to “Denisovan”. And if that would be the case, regardless of what was roaming around in Java or Flores, that means Denisovan is just Homo erectus in the classic taxonomy.
And I say that there was most likely gene flow for quite some time and the mutation rates might be erroneous. Adding up, this means there is no need for H. sapiens being from Eurasia, but like I said before, it could be, in SW Asia at a later point in time (alternatively or together with North + East Africa). I just think we are not at all finished with detecting gene flows in pre-sapiens times. Even on the contrary, we just start looking at it.
You surely have to compare the average of the date range to the old average (660000 to 804000; 640000 to 425000) rather than just cherry pick the oldest date in the range and then declare that you find it more plausible (for mysterious reasons of your own). There is a real change in the average and ranges, obviously.
Probably a bit confrontational there, just don’t get how you could prefer a particular date because you regard it as more realistic when more or less (barring the mandible) all we know substantively about Denisovans come from genetic sequences, and Reich and co obviously will have tons more expertise than just about anyone on that. Surely their date range is *the* date range?
Because of two things:
– Rather continuous development from then on and the stark differences between the species/subspecies at a point in time in which it makes less sense with the late branching.
– My assumption of steady low level gene flow and lower mutation rates (compare with quotation from Hawks)
The 2nd point has to be proven first, but I think the closer date is simply much less likely.
Response:
1) I don’t think it’s really easy to have a good sense of how much can either evolve in 400kya vs 800kya within archaic Homo (estimates have been frequently wrong within other species), even for fossil experts like Hawks, and I’m not sure we have too much morphological evidence to draw conclusions from (very little for clearly Denisovan specimens).
2) Gene flow between African + within Eurasian Early Pleistocene Homo could possibly suppress times down to Middle Pleistocene from what I know (basically you’re proposing multi-regionalism during the pleistocene prior to a recent LMP to EUP expansion)…
But firstly it’s difficult to call that evolving from early pleistocene Asian Homo Erectus exactly (much less *being* Asian Homo Erectus) and secondly, it seems like this is less likely assuming that we know Denisovan and Neanderthals almost perfectly form a clade to AMH, and assuming AMH evolving in Africa (rather than somewhere equidistant from these two) – geneflow with Africa would have to be equal to keep them almost perfectly a clade which doesn’t seem plausible if Neanderthal is evolving in very long time from early Homo in West Eurasia and Denisovans in East Eurasia.
There may be some other things that we know about Neanderthal speciation from the richer fossil record of Heidelbergensis+Neanderthal as well which already directly contradict this idea.
We’ll see, because the relatedness of Neandertals and what was commonly referred to Homo erectus in East Asia (like “Sinanthropus”, Peking man, like quoted above) is obvious and there is little space for anything else in between, especially for any sort of “Denisovan” species/subspecies which was spread from West Sibiria to Melanesia. To construct an artificial group outside of the archaeological record if we have direct progenitors in the Central region will be proven to be an impossible gimmick. If you use different terms for the Peking man and related finds, you get out of it. But you won’t get around those East Asian specimens. Again look what I quoted above. They are all over Asia, in all the places where you find “Denisovans” and they show an evolutionary trend of their own, with cranial capacities at the lower end of the modern human variation.
Concerning the gene flow from archaic sapiens-related groups, we will see how that will pan out, but the latest, fully modern H. sapiens was definitely not the first to make it. Neandertals too show admixture events and we still have no proper H. erectus tested anywhere, yet alone from different regions, or the more developed East Asian ones. We won’t solve that, but to postulate a widespread Denisovan species all over Asia from which we have nothing, and what was proposed are rather more evolved forms of East Asian H. erectus, is rather flimsy. They just need to test some specimens of the taxonomic order of Peking man in East Asia and we know for sure.
Unfortunately most remains are too old, not in good shape, but there are some and sooner or later we will get results.
Obs, you often make interesting and relevant points at this blog. It would be helpful to readers if you could strive to be concise, e.g. as you did in comments at 5:34am and also 2:14pm.
Perhaps your lengthier remarks could form the nucleus of posts that you could refer readers to, for those seeking greater detail?
There should be plenty of space in the fossil record for a Denisovan species that substantially replaced earlier Homo, considering the spans of time involved, don’t worry about that.
We are almost certain to never have adna from clear, unambiguous Homo Erectus. Even Ngandong samples are >100 kya in a tropical region and nothing like that in cool regions. John H talks about samples “In China and Java, (being) attributed to Homo erectus (which) persisted until 200,000 years ago”, but I bet these are just the same Middle Pleistocene Homo who are often not classified this way and are not sure to be descended from the early HE (e.g. Dali is referred to as Homo Erectus but is not really just like HE – https://onlinelibrary.wiley.com/doi/abs/10.1002/ajpa.23305 – “When just the facial skeleton is considered, Dali aligns with Middle Paleolithic H. sapiens and is clearly more derived than African or Eurasian Middle Pleistocene Homo. When just the neurocranium is considered, Dali is most similar to African and Eastern Eurasian but not Western European Middle Pleistocene Homo. When both sets of variables are considered together, Dali exhibits a unique morphology that is most closely aligned with the earliest H. sapiens from North Africa and the Levant.”. The paper goes into more detail on reassesment.)
(Indeed Hawks states: “The similarity of Denisova and Neandertal genomes suggests that they emerged from a single population. This possibly was the early Middle Pleistocene population of Eurasia. Green and colleagues Green:draft:2010 derived Neandertals from a common ancestor with living Africans only 250,000-400,000 years ago. A model including the Denisova data, reported by Reich and colleagues Reich:Denisova:2010 puts the emergence of a Neandertal-Denisova clade at between 190,000 and 520,000 years ago, and the divergence of the Neandertal and Denisova branches around 50,000-100,000 years later. This is later than the time of the last unequivocal H. erectus fossils, and more than a half million years after the Trinil individual – type specimen of Homo erectus – lived. Based on this chronology, the Denisova genome does not represent Homo erectus or any hominin population derived from the initial diversification of Homo.”
When he talks about mutational rate shifting, he is proposing that mutational rates differences could estimate Denisova and Neanderthal slightly earlier but it is clear he is proposing that this is still a fundamentally MPl movement, not He – This would be consistent with a much earlier diversification of Denisovan and Neandertal genomes, making it possible that they came from an early Middle Pleistocene adaptive radiation.)
I looked at Dali before and this is an interesting specimen for sure. Actually its part of the reason why I think archaic sapiens related strains made it into the regional H. erectus (Peking man) derived populations. Because I doubt it was any sort of regional development if the assessment and dating is correct.
The quotes from Hawks just prove how imprecise and unclear the definition of H. erectus is. Now I referred specifically to the Peking man-like samples which have more developed features, larger cranial capacities, were close to Neandertals and in the crucial places for Denisovans.
How reliable estimates are being proven by your quote, namely just about 250.000 for the sapiens : neanderthalensis split as the most recent by Green.
Seriously? That was so off even before aDNA came in, total nonsense.
Sooner or later older samples will get processed successfully and newer ones will complement. New methods and protein comparisons will jump in.
On topic, potentially interesting little paper from a couple months ago https://www.biorxiv.org/content/10.1101/657247v4.full – “Neanderthal-Denisovan ancestors interbred with a distantly-related hominin”
Estimates that in addition to the model of a small 1% super-archaic contribution to Denisovans, the NeanderSovan ancestors that constituted a shared population for about 98.5% Neanderthal+Denisovan ancestry themselves had about a 3% contribution from super-archaic (i.e. a population divergent at about 2million ybp, roughly the time frame for Erectus dispersal). Denisovans up to about 4-5% super-archaic, then.
If correct, that would compress the divergence time for the main trunk of NeanderSovan and Homo Sapiens ancestry down even further than Reich’s latest estimate (so maybe less deep than 660 kya).
Btw, Obs, you’d probably be pleased with this in that last quoted paper:
“Parameter TND is the separation time of Neanderthals and Denisovans. Our point estimate— 737 kya—is remarkably old. Furthermore, the neandersovan population that preceded this split was remarkably small: NND ≈ 500. This supports our previous results, which indicated an early separation of Neanderthals and Denisovans and a bottleneck among their ancestors … Genetic evidence showed that they were from a population ancestral to Neanderthals and therefore more recent than the separation of Neanderthals and Denisovans [9]. However, genetic evidence also indicated that this split occurred about 381 kya [2, table S12.2].
This was hard to reconcile with the estimated age of the SH fossils. To make matters worse, improved dating methods later showed that the SH fossils are even older—about 600 ky—and much older than the molecular date of the Neanderthal-Denisovan split [33]. Our estimates resolve this conflict, because they push the date of the split back well beyond the age of the SH fossils.”
Not Homo Erectus initial dispersal, but also not Reich’s 425 kya average estimate. They also suggest that Sima de Los Huesos samples are substantially older than Reich’s date of 430 kya.
That split of Neanderthal-Denisovan (tND) is estimated by set to 25096 generations, normalized against modernhuman-Neanderthal-Denisovan of a fixed generation number of 25920 = 761 kya.
So a very different model that suggests almost trifurcation of AMH+Neanderthal+Denisovan, rather than Reich lab’s model of a long term NeanderSovan population for about 200kya, or a “stretched-out” version of that model.
Seems the assumptions here would also more smoothly fit with mtdna divergence of (AMH+Nean)+Denisovan+SimadelosHuesos. That’s interesting. Though you’d still need mtdna replacement in Neanderthal from AMH (or vice versa) to get the much younger mtdna divergence in Neanderthal+AMH.
It seems that an early archaic sapiens related group moved into Eurasia, and with Eurasia I mean most of it, but didn’t have the large impact at all, but just mixing into the existing populations of Neandertals and H. erectus.
I discussed and digged into the issue decades before and some still argued for local continuity of H. n. and H. e., I was against that, but they said that they saw local groups becoming “more modern” over time. Now even then it was clear for me, if that trend is real, what is more obvious in H. e. in East Asia, it must be admixture.
Because Hominisation is a clear evolutionary trend, Neandertals and later H. erectus deviated from that trend, they moved in a rather different direction, almost a dead end from my point of view.
They could come back to the main trajectory, but considering evolutionary path dependence, that could have only happened over long period of times. Classic Neandertals were highly specialised in a rather one sided way moving away from the main Hominisation trajectory, but then suddenly, quite late and before being replaced, more modern traits appear. That is no coincidence, there was gene flow from archaic H. sapiens, not just once, but more often, into both Neandertals and East Asian H. erectus. The mtDNA in Neandertals was a first proof, so is the little autosomal DNA, but that’s not where it will stop.
Both made this leaps forward relatively shortly before their extinction not on their own, they got admixture from sapiens. Denisovans will be proven to be East Asian H. erectus with some sort of different admixture, related to archaic H. sapiens.
That’s my best guess right now. Both got archaic sapiens admixture. In the Neandertal case its proven already, for Denisovans it will be proven. This archaic sapiens will be different too, but crucial is that “Denisovans” are the result of mixture and descend mostly from East Asian H. erectus forms like Peking man. I see no other way for coming to terms with the long known archaeological record. But we’ll see, probably I’m completely off…
Re; trends, there certainly is a main Homo lineage trends of accelerating reduction in facial size relative to the neurocranium, and Neanderthals have less of this than Homo Sapiens (even Early Homo Sapiens), and it certainly is the case that later Neanderthals are proportionately larged faced than Early Neanderthals.
On the other hand, Neanderthals did tend to have quite large brains in an absolute sense and fit the endocranial volume trend over time almost exactly as well as AMH (seems complicated by relative lack of very early AMH fossils). (See Fig 1- https://royalsocietypublishing.org/doi/10.1098/rstb.2014.0062 – “Brain ontogeny and life history in Pleistocene hominins”, or a comparable figure dealing with only “Homo Erectus” from a paper listed below – https://imgur.com/a/fXFYmb8).
Brain shape is a little more complex. The long and low brain shape of Erectus was retained more in Neanderthal, though.
(Check out the figures in https://science.sciencemag.org/content/342/6156/326.full – “A Complete Skull from Dmanisi, Georgia, and the Evolutionary Biology of Early Homo”, https://link.springer.com/referenceworkentry/10.1007%2F978-3-642-39979-4_73 – “Defining Homo erectus”, https://www.nature.com/articles/s41467-019-11213-w#Sec6 – “Deciphering African late middle Pleistocene hominin diversity and the origin of our species”).
Was there something about retaining a proportionately long and low brain and a proportionately large face that doomed Neanderthals in the face of H Sapiens, despite comparable brain size? It seems possible simply by looking at extrapolating trends and assuming there is *some* advantage there, but the causal factor is not clear and no one can really say what it is for sure (proposals are made that different brain shapes relative to different regional brain volumes, each of which could be a trump card for H. Sap, but it is hard to say for sure). If there was, why did it even evolve or remain stable? Certainly among modern humans today, those who seem to have proportionately larger faces (seems to be Inuit?) don’t seem to obviously have unsophisticated material culture or social organization necessarily relative to those who present the most extreme AMH proportions (seems like Bushmen?).
It is important to know what Hominisation is about. There was no need for it from later Austrolopithecines on, they already spread beyond their original habitat and earlist Homo forms, before Homo erectus proper, did so as well.
The reason for Hominisation is intraspecific competition in more densely populated areas with additional inputs through changing environmental challenges. So the opposite for an environment good for the trajectory of Hominisation are small, rather isolated populations living in a fairly stable environment, either being “too good” or “too bad” by its adaptive demands.
H. neanderthalensis and H. erectus were both close to being simply dead ends to Hominisation. Neandertals showed development, but not in the typical Hominine way. They lived in small, rather isolated groups with a very conservative, still rather primitive culture and most of the time at the edge of extinction. They were not part of a larger metapopulation which followed the trajectory of Hominisation.
The developments observable in the late phase seem to have been the result of anewed contacts with archaic sapiens, but the input was small, late and sapiens was too much ahead. When the need for expansion emerged in H. sapiens proper, it was their end. Neandertals were not trained for fast (also re-) expansions and group competition, they were behaviourally conservative, inflexible, broad, robust build, very heavy (slower?) and needed a lot of energy. Their brains might have been fairly large, but what we know about its structure so far, points to significant differences. Their size is also not that impressive at all if being put into the context of energy demands and weight.
I think they developed positive traits too, which were useful for H. sapiens which mixed with neanderthalensis, but they were not competitive on their own.
Hominisation was largely the result of large, central metapopulations evolving on, in favourable but still demanding, dynamic habitats. Peripheral, isolated, small scale groups on the edge of survival in extreme environments are highly unlikely to make any step forward on their own. They can produce something which might be useful through backflow to the metapopulation, but they lack the resources to do the leap forward themselves. Rather, they might begin to deviate from the main trajectory of Hominisation to more extreme, less generalist adaptations. That was the story of Neandertals too, with the most drastic example being Homo floresiensis. H. n. lost compatibility with the main human form. Not completely, otherwise there would have been no descendents in moderns, but they were on the way to completely being cut off, becoming a distinct species, a divergency.
What is central and what is the main, or one of the main metapopulations, can change in theory. Like an Ice Age can change the world drastically, what is a good or bad habitat supporting large populations, or new technologies like agriculture, pastoralism are real game changers as well. Though more often than not, even agriculture was developed mainly and most successfully in regions which harboured large populations and culturally more developed people even before the introduction of agriculture. Because most habitats good for agriculture, are good in general and vice versa. Like Near Eastern hunter gatherers, Eastern European steppe foragers or Northern Chinese river people. All had a tendency towards becoming more sedentary, having larger groups and were rather well-nourished before. Obviously you don’t start an expansion from the Kalahari, that simply won’t work out.
I wouldn’t pay too much attention to facial proportions in detail, even though encephalisation and cranium : facial skeleton was a trend. This is not the main aspect in human evolution.
In Neandertals too, it was not just their facial size by the way, but a whole long list of traits which were actually no improvement from Homo heidelbergensis along the classic Homo trajectory, but a more specialist adaptation. It was an evolutionary trend of their (sub-) species. That’s really the point, they branched off from the main trunk of Homo in a very specific way of their own, in isolation, in a very small population, in an extreme environment for which their genetic and technological toolkits were not sophisticated enough to free them from the most urgent pressures.
They HAD TO adapt physically in a very extreme way because of their inability to overcome the challenges in a more intelligent way. One could also say, they moved in that habitat too early, at an too early stage of human development and were caught in it. Extreme environmental adaptation is the antagonist to Hominisation. But this is a relative thing, it depends on how good a people can master their environment. So what might have been very extreme for Homo erectus, was no longer for sapiens.
@Obs, I guess this is where we get into your long-running perspective that comes in most or all matters, where you have a strong hypothesis about between group competition in different areas driving the evolution of more competitive and internally cohesive groups which then expand (which you seem apply to recent developments through human history past prehistory?), and that in your view this tends to happen in more “central” regions of continents. There are some similarities here to the ideas of Turchin I suppose, and all that aasabiya type of stuff.
I have to profess some skepticism of these conclusions and hypotheses in these matters and when it comes to what culture the Neanderthals actually showed relative to Erectus, AMH of the same phase of time (Jebel Irhoud, etc), etc, I have much more interest in reading what Hawks et al kind of talk about in terms of Neanderthal material culture etc from direct observations and excavations which he sources and cites. I’m more interested in talking about the hard details of changes in physiology and genomes in terms of online discussions, because it seems more likely to be fruitful and less likely to be loaded with content about what people are arguing for cultural processes which then can become confused with political arguments without extreme dispassion.
Like, in a sense we see samples probably from the AMH lineage moving into Europe probably unsuccessfully at 210kya (Apidima 1, according to research this year, although this is based purely on neurocranial shape which seems to be within AMH range), and being unable to displace Neanderthals. Then AMH moving in the Near East as represented by Skhul-Qafzeh at 80-kya before being being ultimately replaced by Neanderthal. Then AMH do not really displace Neanderthals in Europe and possibly in the Near East until after 60kya.
(Between Apidima and Skhul-Qafzeh, though closer to Apidima, you also have the supposed AMH maxilla from last year found in Israel and dated to 177,000 to 194,000).
People have argued that possibly through all this, AMH probably had already evolved a full complement of more advanced cognitive behaviours than Neanderthal* and were kept out of Europe and replaced in the Near East by Neanderthals pesky superior physiological adaptations to climate… That AMH were always more cognitively and culturally advanced than Neanderthal (along the general trend), but this only became a large enough advantage at the point AMH is able to expand into Europe. But I am not sure if this is the case, or that there just wasn’t much or any of an actual AMH cognitive advantage, at least until post 50kya.
*and this is all part of the “Full behavioural modernity at the point of intra-African divergence at 170kya or so, or older, at least” argument, which itself is a mix of well reasoned argument and less well reasoned stuff that has possibilities that want to be avoided.
E.g. Hawks blogpost 2016 – http://johnhawks.net/weblog/reviews/neandertals/demography/ecocultural-model-gilpin-2016.html – (T)he Neandertals persisted in Europe and central Asia long beyond the entry of modern humans into Asia. Initial modern humans in Asia exhibited no obvious cultural superiority over other Middle Paleolithic people, who were presumably archaic humans. “No cultural superiority” is maybe an understatement: Archaeologists have trouble finding any consistent material culture differences between people in West Asia before 50,000 years ago.
Tens of thousands of years later, when modern humans did start to enter Europe, they seem to have mixed with Neandertals more extensively. The later Neandertals were making symbolic artifacts, using pigments, feathers and other ornaments. The people who made the earliest Aurignacian, often assumed to be the earliest modern humans in Western Europe, did not have the intensity of symbolic artifacts of later Aurignacian and Gravettian people. Instead they seem to have been sparse and little different in most cultural practices from Neandertals.
In other words, at the critical time when modern humans entered Europe and their population apparently grew, there was little cultural difference between them. There is even less evidence that there was any cultural advantage to modern humans who spread across southern Asia prior to 50,000 years ago.
Now maybe that’s a superseded summary of the field post the last four years, or it is not a consensus summary of the field, but it’s at least one expert’s fairly recent opinion.
To me its obvious that archaic sapiens “wasn’t there yet” to cross climatic borders with ease, they lacked the genetic and cultural toolkit as well. That’s why the first sapiens related archaic forms were not able to keep up in the temperate to cold climate the Neandertals inhabited on the long run. But it seems that admixture took place and more modern impulses reached the Neandertals (mtDNA and autosomal proves that already).
The first sapiens migrations were still limited to “easy accessable” regions which were similar to the warm climate of the Homo sapiens center. So they moved along the coastline East, rather than successfully North. That’s why we see mixture at the fringes and early AMH traces in the East, but the Neandertals could hold their ground, especially when the climate became less favourable for sapiens once again.
It was the more advanced, later fully evoled modern sapiens migrations from the Near East, which crossed the climate borders rather quick and replaced the Neandertals and “Denisovans” (most likely H. erectus with archaic sapiens admixture) at a rapid pace. The crucial point is: The fully modern sapiens needed to enter the scene and cross the climatic borderline to the temperate to cold climate.
“I guess this is where we get into your long-running perspective that comes in most or all matters, where you have a strong hypothesis about between group competition in different areas driving the evolution of more competitive and internally cohesive groups which then expand (which you seem apply to recent developments through human history past prehistory?), and that in your view this tends to happen in more “central” regions of continents.”
If you have a sparsely populated, unfavourable region, with a stable climate and little to no influences from outside, the impulses for development are rather weak. You might end up in stagnation or environmental adaption, both can lead to leaving the Hominisation trajectory. If you have densely populated, more favourable but demanding region, with a lot of human groups competing with each other, both genetic and cultural development will, usually, happen at a much higher pace. Also, humans will be more likely to compete “to the bitter end” for regions which are prime habitats. Like the tropical forests or deserts are the last refuges for those which lost the fight for better spaces quite often, with one group after the other coming from the Central regions in. In the same way, keeping control of the Volga and Don, the Nile, Euphrat and Tigris, Indus or Hwangho in particular, is nothing you give up that easily. Its not just “another forest” like any other place, its a Central, fertile region and it was like that even before the advent of farming and animal husbandry. The clans fought for saving their access to these resources. That’s actually one of the reasons why they started farming and breeding, they were used to becoming more sedentary even before agriculture. The periphery is very different in its demands, its selective pressures on foragers living in isolation, with less frequent wars, lower organisation and a higher value of the individual, because there were not as many around. This relates to sexual selection, but this would be a long debate.
It is very obvious that the large metapopulation of Homo sapiens lived in the Central region of its time, probably in a wide stretch of land from Northern to Eastern Africa, to the Near East.
The contacts and admixture with Neandertals might even have been helpful for crossing the borderline, but in any case the idea of Central regions from which expansive populations emerge, which, one wave after another, change whole macroregions and continents, was never doubtful for anyone looking at the bigger picture. And all we have seen from ancient DNA so far proves just the correctness of this assumption. East Asia for example is just a prime example. The periphery is just unlikely (not impossible) to make such developments on its own. But whats central and what’s peripheral can change over the course of time. Looking at East Asia for example, the Hwangho is now by far not as Central as it was for many thousands of years, yet its history shows off in the demographic power house of China to this day.
Even for Homo erectus, the more Central and developed position of the East Asian forms vs. those of South East Asia is very, very obvious, e.g. in cranial capacity.