Did Neanderthals inhabit Southern California 130,000 years ago?

Ever since the Holen (2017) paper describing human modified bone and stone tools from Southern California dated to 130,000BP, I have been intrigued by the possibility that some form of human was most likely well established in the Americas by this date.

But which one?

Previously I have detailed the Holen et al. (2017) evidence here and here and reviewed the possibility that the hominid could have been Homo erectus here.

I have also considered the Denisovans as a candidate species (see here).

Now I am going to consider the evidence that Homo neanderthalensis – Neanderthals were the species of hominin in southern California 130,000BP.

The evidence that Neanderthals reached America by 130,000 BP can be divided into two areas. Firstly, the direct skeletal evidence and secondly the genetic or DNA evidence. The first I will cover in depth, the second in overview.

Therefore, before we start, I think a good look at Neanderthal anatomy would be informative. The most strikingly different feature of the skeleton is the shape and proportions of the skull:

Clockwise from top left:

Female Neanderthal (National Geographic 2008), Male Neanderthal (Sci-News 2014) and Potter (2006).

Neanderthal skeletal features

1. Cranial features: Long flat braincase, receding forehead, pronounced brow-ridge (supraorbital torus), large nasal cavity, circular orbits, projecting midface and little or no chin. Distinct, temporal labyrinth of ear bones. Large anterior teeth marked by strong shovelling, marked labial convexity, and prominent lingual tubercles, postcanine teeth showing taurodontism (enlarged pulp chambers), the majority of specimens with a retromolar space.

2. Post cranial features: Conical ridge cage (wider at bottom), limb bones thick walled and relatively short, flaring hip bones, collar bone relatively long, trunk relatively short, hand bones robust.

Human skeletal features

1. Cranial features: High rounded braincase, vertical forehead, little or no brow-ridge (supraorbital torus), narrow nasal cavity, variable orbit shape: angular, rectangular or round, little projection of midface and pronounced chin. Temporal labyrinth of ear bones metrically different from Neanderthals. Rear tooth arcade smaller in size than Neanderthal, lack shovelling, reduced labial convexity (or smooth), and reduced lingual tubercles, postcanine teeth showing no taurodontism, no retromolar space.

2. Post cranial features: Cylindrical ridge cage, limb bones thinner walled and relatively long compared to Neanderthals, narrow hip bones, collar bone relatively short, trunk relatively long, hand bones slender.

It should, therefore be easy to differentiate between a Neanderthal skeleton and one of a modern human. And it is. Unfortunately, full skeletal remains are rare. Often, all that archaeologists discover are a partial skull or a few teeth or some portion of the skeleton. Thus, identification to species may be far more difficult.

Furthermore, while exhaustive, metric analyses have been looked at every comparative measurement of humans and Neanderthals there is some overlap, in a large number of the measurements. This can lead to extreme difficulty in species assignment, especially where the bones found are small and/or fragmentary or from some non-diagnostic region of the skeleton.

Lastly an unknown number of hominin species were present across east Asia during the era in which Neanderthals were present. Some of these are poorly represented in the fossil record (e.g. Denisovans) or poorly delineated (e.g. ‘Archaic Homo Sapiens’/Homo heidelbergensis) or unconfirmed as being present in the region – including Neanderthals themselves! A thorny issue indeed, therefore.

Considering the fossil evidence, one could quite reasonably conclude that it is unlikely that Neanderthals reached America simply because their CONFIRMED geographic distribution is limited to Western and Central Europe and central Asia as far as the Russian Altai.

To address this problem, I have sought out papers on skeletal remains from central Asia and China to try to critically assess whether Neanderthals were present, sufficiently close to Beringia to be considered likely candidates for the peopling of the Americas prior to 130,000BP.

I have created a google map showing the distribution of fossils firmly or tentatively attributed to Neanderthals: 

The Skeletal evidence

To assess the likelihood of whether, Neanderthal reached America, I am going to consider, what I think are 5 key sites:

1. Denisova Cave, Russian Altai

2. Salkhit, Northeast Mongolia

3. Hetao Man, Ordos plateau, Inner Mongolia

4. Xujiayao, Nihewan Basin, China

5. Jinsitai Cave, Inner Mongolia, China 

1. Denisova Cave, Russian Altai

As can be seen, the furthest eastern, confirmed Neanderthal site is Denisova cave. This site is an extremely rich one, having been occupied by Denisovans, Neanderthals and Anatomically Modern Humans for up to 170a and 270ka approximately, although the scattered literature does not make it easy to find unequivocal dates.

Dating

The dates at which each species of hominin lived in the cave are actually, quite difficult to pin down. Although quite a number, of papers and endless blog posts cover the discoveries made at Denisova cave, the exact timings of each occupation are complex and confusing. From the plethora of incomplete data, I have compiled this rough chronology:

For a more complete explanation of how I arrived at these dates, including extensive references see my, later supplementary post.

The fossils

The actual, fossil, Neanderthal, material found is quite disappointing. They consist of:

A toe phalanx – ‘Altai Neanderthal’ (Denisova 5)

Neanderthal toe phalanx from Prüfer et al. (2014)

Denisova 11

A morphologically unremarkable bone from the 2014 excavation, identified as Neanderthal by Brown et al. (2016) using the collagen fingerprinting technique:

Denisova 11 from Brown et al. (2016). Original caption reads: Figure 2. Photograph of DC1227, detailing each visible surface of the bone.

Additionally, two samples of sediment from Denisova cave also yielded Neanderthal DNA. The analysis by Slon et al. (2017), put Neanderthals in different parts of the cave and at different times than any other archaeological evidence, has been able to, substantiate.

Discussion

These remains and the DNA samples from soil, are the eastern-most unequivocally Neanderthal samples yet found. Their dating puts Neanderthals in the region at ca. 110,000 years ago, consequently they are slightly, too late to have been the ancestors of the hominids that may have made it to America by 130,000BP. Whether their ancestors were in the region, prior to this date as they were in Europe is an open question.

2. Salkhit, Northeast Mongolia

The fossils

From Coppens (2008): “A skullcap was discovered in northeastern Mongolia, during gold mining prospecting by the Baidan-Erdes Company at the Salkhit site (Bian-Oulziit, Somon), in 2006. The bones were found by a worker, in a pit at a depth of 6m. It is well-preserved, although fragmentary. This calvarium is composed of the frontal squama, part of the nasal bones and of the parietals. In the pit wall, can be seen a series of fluvial deposits interbedded with loess separated by a relatively thick mass of fallen rocks, with angular fragments. The fossil would rather come from the adjacent, river, terraces.”

The Salkhit skullcap from Coppens (2008). Original caption reads: Fig. 2. Picture of the Salkhit skullcap in norma frontalis (A), norma lateralis (B), norma verticalis (C), and norma basilaris (D).

“Concerning the dating of the fossil, the attribution of the Salkhit calva to the Late Pleistocene has been suggested based on faunal remains (woolly rhinoceros) found in possible association.”

In Coppens’ study, its morphology was compared by multivariate analysis, with a large sample (68 specimens) of Pleistocene hominid skulls from Europe, Asia and Australia.

“This preliminary study of a human skullcap discovered at Salkhit, Northeast Mongolia, in 2006, shows a mosaic of traits. Plesiomorphies can be seen on the frontal bone: developed brow ridges and a keeled squama. Apomorphies can be observed: high and back-located parietal eminences and absence of a sagittal keel. The skullcap seems to share also some features with Neanderthals that can be observed on the lower part of the frontal bone and in the nasal and orbital region such as a supratoral sulcus, a prominent glabella, prominent rounded lateral supraorbital margins, and a well-defined inward nasion. The comparison of the dimensions of the skullcap with those of skullcaps of a reference sample by multidimensional scaling analysis shows similarities with Neanderthals, Chinese Homo erectus and West/Far East Archaic Homo sapiens.”

Multivariate plot from Coppens et al. (2008). Original caption reads:

Fig. 3. Multidimensional scaling of the fossils considered in this study. The plot was computed on a distance matrix between all the 68 specimens, which considers 11 measures of length, width, height of the calva.

In terms of which metric measurements were used in the comparison the authors say: “Concerning the metrical aspect of this study, 11 traditional measurements have been considered (LGL, WMX, WFS, WFI, AFR, APA, CFR, CPA, WBO, WIO, WOG/D) on the 68 skulls (including the Salkhit calva), whose area of interest had been reduced to the calva.”

As can be seen from the diagram above, the Salkhit skullcap groups with several well-known Neanderthal fossils. These include the original Neanderthal from Feldhofer grotto in the Neander Valley, Germany; La Ferrassie and La Chapelle-Aux-Saints both in France; Guattari 1 from Monte Circeo, Italy; Šaľa Slovakia; Krapina, Croatia; Teshik Tash, Uzbekistan and the slightly controversial Amud 1 from Israel.

It also groups with some skulls attributed to Homo heidelbergensis such as Arago, France; Broken Hill, Zambia; Petralona, Greece; Steinheim, Germany and Zuttiyeh from Israel.

It also groups with a loose group of ‘Archaic Modern humans’ including the Czech specimens from Předmostí, and the material from Djebel Irhoud in Morocco.

Finally, In the same grouping are the Zhoukoudian 2, 3 and ‘reconstruction’ specimens from China – all Homo erectus.

Whilst, the majority, of the specimens that the Salkhit skullcap group with are Neanderthal (n = 8/18) and within the body of the paper, note the similarities with H. neanderthalensis the authors seem to deliberately avoid assigning the Salkhit skullcap to this species. Instead they note its affinities with Chinese H. erectus, and West/Far East Archaic H. sapiens and unaccountably conclude: “we cautiously attribute the Salkhit calva to an archaic Homo sapiens.”

By this I can only assume they mean the group of specimens including the remains from Petralona and Steinheim, a group of specimens, which, most workers in the field assign to H. heidelbergensis. In fact, these two specimens are the closest to the Salkhit skullcap on their multidimensional scaling plot. So, their assignment of the specimen to this group does have some logic. However, I find it extraordinary that the authors do not explicitly acknowledge to which group they are assigning the fossil! In fact, the words ‘Homo heidelbergensis’ appear nowhere in the paper.

Other evidence brought forward in the paper, but not explicitly stated to inform the tentative, diagnosis is that drawn from the endocast of the interior of the skull. The authors state: “The study of the silicone endocast shows a clearly marked vascular system, although unbalanced between frontal and parietal areas. The anterior meningeal branches at the frontal area show tiny reticulations unequally developed on the left and right sides. In contrast, the posterior branches are strongly marked and more developed. Unfortunately, the fragmentary state of the calva does not allow the complete study of the posterior meningeal branches, which are only preserved on the half of their length.”

As the paper, does not explicitly say how this evidence relates to species identification, I did a little research. From Píšová (2017) “A second difference in the middle menin­geal vessel traces among hominids concerns the relative proportions of the anterior and posterior branches (Grimaud-Hervé, 2004; Saban, 1995). Many archaic specimens (generally included in the Homo erectus hypodigm) exhibit posterior dominance of the network, where the posterior branch is more reticulated than the anterior. By contrast, most Neanderthals and modern humans exhibit anterior dominance of the mid­dle meningeal branches.”

It therefore, seems that evidence from the specimen more closely aligns it with Homo heidelbergensis, or as the authors put it ‘archaic Homo sapiens’. Having said that some features certainly indicate a relationship with Neanderthals, Coppens again: “Lastly, in the nasal area, the clear inward position of the frontonasal suture outlines a well-defined inward nasion. On the endocast, the absence of the sphenoparietal sinus has to be mentioned.

This particular sinus has commonly been proposed as a Neanderthal autapomorphic trait, since it is more rarely observed in modern populations and poorly expressed in Asian H. erectus.”

Another paper by Lee (2015) has this to say: "The Salkhit skullcap has a mostly complete frontal, two partially complete parietals, and nasals. While no chronometric date has been published, the presence of archaic features has led to a potential affiliation with archaic hominin species. If it is indeed Homo erectus or archaic Homo sapiens, Salkhit implies a much earlier spread of hominins farther north and inland Asia than previously thought. In this paper, the nature of the archaic features in Salkhit is investigated. The Salkhit skullcap morphology and metrics were compared with Middle and Late Pleistocene hominin fossils from northeast Asia: Zhoukoudian Locality 1, Dali, and Zhoukoudian Upper Cave. Results show an interesting pattern: on one hand, the archaic features that Salkhit shares with the Zhoukoudian Locality 1 sample also are shared with other later hominins; on the other hand, Salkhit is different from the Middle Pleistocene materials in the same way later hominins differ from the Middle Pleistocene sample, in having a broader frontal and thinner supraorbital region. This may reflect encephalization and gracilization, a modernization trend found in many places. It is concluded that the archaic features observed in Salkhit are regionally predominant features rather than diagnostic features of an archaic species."

Dating

From Coppens et al. (2008): “Concerning the dating of the fossil, the attribution of the Salkhit calva to the Late Pleistocene has been suggested based on faunal remains (woolly rhinoceros) found in possible association. Nevertheless, this assumption, currently based on biochronology, needs to be confirmed by further fieldworks and absolute dating.”

And from Lee (2015): “No chronometric dating has been published yet, and suggested dates range from early Middle Pleistocene to terminal Late Pleistocene.”

Given the internationally accepted dates for the Pleistocene are:

Early Pleistocene: 2.6M BP – 781,000BP

Middle Pleistocene: 781,000BP – 126,000BP

Late Pleistocene: 126,000BP – 11,700BP

This gives us a range of 781,000 to 11,700BP! Extremely unhelpful. Even the associated faunal bones do not tell us much: Woolly Rhinoceros were around from about 3.6M years ago with the last population, so far discovered going extinct ca. 10,000 years ago in western Siberia.

From the position of the find under 6m of sediment, which in itself, probably represented redeposition from its original position, my opinion (for what it is worth) based on sedimentation rates and morphological similarities to the Petralona and Broken Hill specimens of Homo heidelbergensis, is that the fossils range from ca. 300,000 to 100,000 years old.

Other evidence - lithics

Finally, lithics discovered in the immediate vicinity by Teyssandier et al. (2014) may give some further clues to the identity of the hominin represented by the Salkhit skullcap: "We report here preliminary results of an on-going international project triggered by the discovery of the Anatomically Modern Human skullcap from Salkhit, in Northeast Mongolia. The survey led to the discovery of the Havstgayt Valley ca. 20 km to the South-East of Salkhit. Another clear Upper Paleolithic component has been discovered, in the vicinity of, the rock shelter. Massive and convergent blades with facetted platforms have been collected along a gentle slope. They are consistent with an attribution to the Initial Upper Paleolithic technocomplex. Although the latter is well known in the Siberian Altai, in the Transbaikal and in North-Central Mongolia, Havstgayt currently stands as one of the easternmost localities that document such technical tradition." These lithics could be associated with a range of hominins, although the connection with the Altai lithics is suggestive of either Neanderthals, Denisovans or ‘archaic Homo sapiens’.

Discussion

On a personal note, looking at the shape of the orbits, visible in the photograph from the paper, I am struck by the similarity with two specimens, of Homo heidelbergensis from Rightmire (2017):

Strikingly, similar, don’t you think? Enough said.

In assigning the specimen to ‘archaic Homo sapiens’ instead of Homo heidelbergensis or Neanderthals, one could conjecture, that both Coppens and Lee did so because of the preferred theory of evolution, that their hosts, the Chinese, prefer.

Put simply, the prevailing theory in China, as insisted on by the government is a revised version of the “Multi-regional Evolution” referred to as “Continuity with Hybridization. This explanation of human origins was initially put forward by Wu, (1998) and updated by Gao, et al. (2010).

This theory holds that after, Homo erectus left Africa, perhaps as long ago as 2 million years ago, modern humans evolved separately in different parts of the world from more primitive hominids. In this so-called “multiregional” scenario, Australian Aboriginals are derived from Java man (i.e., Javanese H. erectus), modern Chinese from Peking man (Chinese H. erectus), today’s Europeans from the Neanderthals (H. neanderthalensis) with some admixture from Cro-Magnon.

Whilst this theory, has been disproved by multiple lines of evidence, over the last two decades, Chinese politicians still insist that their scientist continue promulgate this profoundly flawed theory.

What species of hominin this specimen represents: Neanderthal, Early/proto-Neanderthals, Homo heidelbergensis or so-called ‘archaic Homo sapiens’ is an open, question.

3. Hetao Man, Ordos plateau, Inner Mongolia, China

A partial skull and various post cranial, discovered at various times, on the edge of the Ordos Plateau, Inner Mongolia, have been variously attributed to Archaic Homo sapiens, ‘transitional’ Homo erectus and controversially (for the Chinese) Neanderthals.

The location, exact nature of the human remains, their dates and the type of hominid the bones represent discovered at this site on the Salawusu river were extremely difficult to pin down and are ALL uncertain!

Firstly, as noted by Gilbert (2017) “Actual position of cranium is not published” It gives the following “Location: Salawusu, Xarusgol (originally called Sjara-osso-gol and also Salawusu) River, Uxin Qi (Dabqig) County, Inner Mongolia, Mongolia” but suggests that the coordinates for Milanggouwan section in Zhou et al. (2002) are pretty close. In their paper, they give the coordinates as 38.75N, 108.5833E. This turns out to be in an unlikely location well away from any river course and hence must be incorrect! Looking further into the location of the Milanggouwan section further I found a second paper, this time by Wen et al. (2009) that clearly identifies the exact spot this stratigraphic section is found in: 37.75795N, 108.53582E. Furthermore, Liu and Lai (2012) identify the same location in their map and name it as the “archaeological Salawusu site”, its identity and geographical location, therefore seems certain. Consequently, I have used those coordinates on my map of Neanderthal sites. Additionally, Shang, Liu and Wu (2006), give this useful map of the various sites in the area:

For those interested in greater precision, I have converted the above into a Google Map:

The name of the site has also been variously recorded. Initially called the Sjara-osso-gol site after the then name of the river by Teilhard De Chadin and Licent (1924) it changed to the Salawusu river site. Most recently named the Xarusgol Valley site. The river name has, unfortunately also had a number, of name changes from the Sjara-osso-gol, to the Salawusu to the modern Wuding or Wuding He river. To compound matters, the section of the Wuding river shown on Google maps abruptly changes to the Honglui river without apparent reason. The site under any name is unsearchable in any case on either Google Earth or Google Maps.

Then there is the further complication that the Yongding (or Yongding He!) river in Shanxi Province, is sometimes known as the Wuding river and flows northeast through Inner Mongolia before heading southeast into Hebei Province.

The fossils

The fossils from the site in were discovered over three stages:

Firstly, De Chadin recovered an early Homo sapiens tooth in 1922. The authors – Licent et. al. (1927) describe the discovery thus: “In the course of, our excavations of 1922-23 in the Sjara-osso-golpalaeolithic levels, no human bony remains had been noticed, except one femur and some other pieces of very doubtful origin. Recently, while examining occasionally a residuous material of those excavations, we were surprised to notice, amongst Gazella teeth and pieces of Struthiolithus, a human upper incisive, strongly fossilized. The great antiquity of this tooth is not absolutely, certain, because it was collected (as the associated fossils) in a place where Pleistocene sands are more or less mixed with the basal gravels of a modern terrace of the Sjara-osso-gol. Nevertheless, the grade of fossilization of the specimen and the fact that it has been found in association with a large number of, undoubtedly fossil bones (Rhinoceros, Elephas, etc.) made us fairly sure that it is of Pleistocene age. The place of the find (which occurred in August 1922) is only 500 meters distant from the point where palaeolithic implements and numerous kitchen remains were dug out, and on the same level.”

A description of the tooth is given in Derevianko and Lü (1993): “The tooth is very well preserved; the crown has not been eroded and the root has not reached maturity; it is similar to that of a modern child. Because of the protrusion of the two sides of the lingual surface of the molar, the centre of this surface is concave, or shovel-shaped and bears the characteristics of present-day Mongolian teeth. D. Black has done preliminary research on this tooth and named it Hetao man.”

Next, in 1957, according to, Derevianko and Lü (1993), workers from the Inner Mongolian Museum found a section of parietal bone and a portion of a femur in the terrace deposits near the village of Dishaogouwan: “The thickness of the parietal indicates that it approximates to that of Neanderthal man and is larger than that of contemporary man. Traces of pressure of the artery branches on the inside of the parietal bone were greater on the back branch than on the front, further indicating primitivity. The wall of the femur is thick and the marrow cavity small, representing only a third of the diameter.”

In Wu and Poirier (1995) the discovery is however credited to Yupin Wang of the Bureau of Cultural Affairs of Nei Mongol Autonomous Region, who published a description of this and a second parietal in 1961 [Wang (1961)].

Between the mid 1950’s and 1980, several, surface finds were made, presumably washed out of the sediments of the Salawusu formation. These however, are not obviously, in good archaeological context have and cannot therefore give an indication of the site’s antiquity without direct radiometric (¹⁴C) dating.

Finally, in 1980, as reported by Shang and colleagues (2006) a human scapula was found in situ in the lower part of the Salawusu formation in. They include an image of the shoulder blade:

Original caption reads:

Fig. 2. Fossil human scapula from Salawusu site. (a) Frontal view; (b) lateral view: glenoid fossa; (c) occipital view; (d) lateral view: the axillary border.

Their conclusions were: “Based on the comparisons between this scapula and the scapulae of Neanderthals, Skhul/Qafzeh fossils, Eurasian Upper Paleolithic specimens and recent, modern humans on the glenoid fossa, axillo-spinal angle, axillary border and other features, the present authors arrived at a preliminary conclusion that this Salawusu scapula is characterized by modern features of Upper Pleistocene humans mixed with a Neanderthal-like feature.”

Dating

Tooth and Femur

Teilhard de Chadin ca. 275 years old [Keates and colleagues (2007)].

Parietal with Neanderthal features Museum of Inner Mongolia 30,000-50,000BP based on position of find in the stratigraphic section [Shang, Wei and Wu (2006)]

Scapula 70.9±6.2ka BP to 124.9±15.8 ka BP by TL method [12]. Dates from 44±7 ka BP to 63±3 ka BP [13], 35.34±2 ka BP [14]and 61―68 ka BP [15] are obtained for the lower part of this layer by 230Th, IRSL and 14C respectively. [Shang and Colleagues (2006)]. I have absolutely no idea which the best date is so let us average them all! Average date = ca. 64,000BP with a range of 33,000-140,000BP.

Other evidence – lithics

A large, number of, lithic tools have been recovered from 6km length of riverbank. A number, of papers, in Chinese have been published on these but the technical details of these is unavailable in English.

Discussion

The original tooth and femur found in 1922 by Teilhard de Chadin and colleagues have been proven to be 17^th century by Keates et al. (2007).  The authors note “We conclude this report by emphasizing the importance of the direct dating of human fossils in East Asia and elsewhere. We caution scholars not to rely on dating results determined by the age of organic materials inferred to be associated with bones or to be unduly influenced by the fossilized appearance of human bones.”

Not surprisingly the Chinese authorities have been quite reticent about having any more of the human fossils from this site directly dated. Their policy now seems to be to date the sediments in which the fossils are found. Presumably this strategy is designed to avoid any unwelcomely late dates for what the Chinese state contends are early Pleistocene Homo sapiens. Some have postulated that this is due to a desire to not have hard data conflict with ‘Continuity with Hybridisation’ model of human evolution.

As previously mentioned, the Chinese state supports scientists who publish papers that bring forward evidence that could support the idea that the Chinese are descended from hominins that evolved in situ in China to form an entirely separate lineage of modern humans. In short, the Chinese today do NOT descend from humans from Africa. Therefore, evidence must be found to support this theory. Conversely evidence which contradicts this position is most unwelcome, for instance Keates’ dating of the 1922 femur.

Looking at these fossils in a broader context of human evolution, one must see that Neanderthal skeletal material – a European and west Asian species - would also be MOST unwelcome in the light of the prevailing state sponsored theory of Chinese origins.

Which is the whole point in including these specimens in my review of which species could have made it to America by 130,000BP. We have Neanderthals in the Altai of Russia, and now almost certainly in China, but how much further did they disperse?

4. Xujiayao, Nihewan Basin, China

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The Chinese palaeontological, site of Xujiayao is situated approximately 200km due west of Beijing on the north-western edge of the Nihewan Basin. Lying on the west bank of the Liyi River, a tributary of the Sanggan River, it actually consists, of two localities: 73113 a little north of Xujiayao Village in Yanggao County, Shanxi Province, and 74093 south-east of Houjiayao Village in Yangyuan County, Hebei Province. The northern site [73113] was discovered first in 1974.

Excavated in 1976, 1978 and 1979 and once more to secure additional dating samples in 2007 and 2008. The majority of, the ca. 30,000 lithics, a vast array of animal bones and most importantly a number of hominid fossils were recovered from locality 74093. In total 20 finds were made: Twelve parietals, one temporal, two occipitals, one juvenile maxilla, one mandible, two isolated left upper molars and one lower molar. Of the hominid fossils recovered 19 came from the southern locality while one single find was made at the northern one. Unfortunately, I have been unable to determine which, lone, fossil came from the northern locality.

Dating

In terms of the dating, the latest paper by Tu et al. (2015) give a weighted mean age of 0.24 ± 0.05 Ma.

The fossils

Temporal Bone

The temporal bone is that area of the skull containing the ear bones, it is of particular, interest, to palaeologists as the form of the inner ear or in technical terms, the temporal labyrinth, is different in Neanderthals compared to other Pleistocene and recent human species.

The positions of the temporal bone and inner ear bones (temporal labyrinth) can be seen at left and right below (adapted from Biology Study Guides (2009) and Didier Descouens (2018) respectively):

A view of the fossil temporal bone, CT image and computer extracted view of inner ear bones superimposed on a view of the Xujiayao site from Phys.org (2014).

Original caption reads: The Xujiayao 15 late archaic human temporal bone from northern China, with the extracted temporal labyrinth, is superimposed on a view of the Xujiayao site. Credit: Institute of Vertebrate Paleontology and Palaeoanthropology, Chinese Academy of Science.

A detailed view of the temporal bone from Wu et al. (2014):

Original caption: Figure S2. The Xujiayao 15 temporal bone, in lateral (a), medial (b), posterior (c) and inferior (d) views.

The posterior view is slightly posteroinferior. Note that a sutural ossicle in the region of pterion, along the anterior squamous portion, is absent, such that the original squamous contour was probably more rounded anteriorly.

On micro CT scan the temporal bone or inner ear of the fossil Xujiayao 15 was noted to be unusual for eastern mid-Pleistocene hominids. Metric comparisons were therefore made and the results were clear. The morphology of the temporal labyrinth

of Xujiayao 15 and the relative proportions of their anterior, posterior, and lateral canals are consistent with Neanderthal traits.

In particular, Neanderthals, have been noted to have relatively small anterior and large lateral canal radii, which this specimen exhibits. Secondly, it has a more inferior position of the posterior canal relative to the lateral canal. This can be clearly seen in Fig. 1 from Wu, et al. (2014):

Original caption reads: Reconstructed temporal labyrinths of East Asian Pleistocene humans from Lantian 1 (reversed), Hexian 1, Xujiayao 15, and Liujiang 1 (reversed), in lateral (Upper) and superior (Lower) views.

The authors, did note however, that in external morphology the Xujiayao temporal bone had a number of morphological dissimilarities to those from Neanderthal specimens. They were also outside the range of variation of Homo erectus [Lantian and Hexian specimens this study] and modern humans [Liujiang this study].

Having noted these differences, the discussion section raises some interesting thoughts: “It is therefore unclear whether the Neanderthal labyrinthine configuration, and by extension that of Xujiayao 15, can be attributed to other aspects of their biology. Moreover, the overall cranial morphology of the Xujiayao sample is incompletely known and their postcrania are unknown. These considerations of the Xujiayao 15 labyrinth also raise questions regarding the use of individual features (whether morphological or molecular), in the absence of relatively complete paleontological remains, to identify the presence of Neandertals in regions outside of their well-documented core area of western Eurasia (west of ∼45° E, versus ∼70° E for Obi- Rakhmat and ∼114° E for Xujiayao).”

Mandible

Adapted Image of the partial mandible, adapted from figs. 1 and 2 Wu and Trinkaus (2014):

Original captions read:

Fig. 1. Views of the Xujiayao 14 mandibular ramus. Above left: lateral; above right: superior; below left: medial; below right: posterior and slightly inferior. The condyle and the anterosuperior margin of the mandibular foramen (with the lingula) were lost postmortem. The coronoid tip was reduced antemortem, such that the original tip should have been higher and slightly more anterior.

Fig. 2. Ramal discrete traits, indicated on the Xujiayao 14 mandible. A: mandibular notch (asymmetrical); B: mandibular foramen posterior mar-gin (open); C: superior medial pterygoid tubercle (enlarged); D: notch crest to condyle (lateral); E: gonion (everted); F-F: minimum ramus breadth.

From their conclusion: “The early Late Pleistocene mandibular ramus from Xujiayao, Xujiayao 14, presents a wide ramus combined with several generalized archaic Homo discrete features of the ramus (asymmetrical mandibular notch, lateral notch crest on the condyle, open mandibular foramen and everted gonion). It exhibits features that are known principally among the western Eurasian Neandertals, an enlarged superior medial pterygoid tubercle in the context of small inferior ones, plus an inferred retromolar space. As the only available eastern Eurasian late archaic human mandible, and hence an N = 1, it cannot resolve the affinities among late archaic humans across Eurasia. However, rather than simply suggesting Neandertal affinities for this eastern contemporary of them, it raises questions regarding the distribution and significance of purported regional morphological variants among Pleistocene archaic humans.”

Looking at this second piece of evidence, critically, once again, another part of the skull exhibits Neanderthal features.

Partial Maxilla and dentition

From Xing, et al. (2015) abstract: “It is generally accepted that from the late Middle to the early Late Pleistocene (∼340–90 ka BP), Neanderthals were occupying Europe and Western Asia, whereas anatomically modern humans were present in the African continent. In contrast, the paucity of hominin fossil evidence from East Asia from this period impedes a complete evolutionary picture of the genus Homo, as well as assessment of the possible contribution of or interaction with Asian hominins in the evolution of Homo sapiens and Homo neanderthalensis. Here we present a comparative study of a hominin dental sample recovered from the Xujiayao site, in Northern China, attributed to the early Late Pleistocene (MIS 5 to 4). Our dental study reveals a mosaic of primitive and derived dental features for the Xujiayao hominins that can be summarized as follows:

i) they are different from archaic and recent modern humans,

ii) they present some features that are common but not exclusive to the Neanderthal lineage, and

iii) they retain some primitive conformations classically found in East Asian Early and Middle Pleistocene hominins despite their young geological age. Thus, our study evinces the existence in China of a population of unclear taxonomic status, with regard to, other contemporary populations such as H. sapiens and H. neanderthalensis. The morphological and metric studies of the Xujiayao teeth expand the variability known for early Late Pleistocene hominin fossils and suggest the possibility that a primitive hominin lineage may have survived late into the Late Pleistocene in China.”

Xing et al. (2015) Fig 1. Original caption reads:

The Xujiayao immature left partial maxilla (PA 1480) with partial left maxillary dentition (I: top view; II: bottom review; III: tomographic slice obtained from micro-CT scanning)

Once again a further piece of the collected remains exhibits Neanderthal traits. Although it is tempting for me to hypothesise, that these remains represent Neanderthals in China, I will leave the last word to Ao (2017):

“Recent studies of the Xujiayao Homo fossils (Wu et al., 2012, 2014; Wu and Trinkaus, 2014; Xing et al., 2015) indicate that they are more similar to Neanderthals than to H. heidelbergensis or H. erectus. For example, the bi-level nasal floor in the maxilla of Xujiayao individual I (PA1480) and the presence of a well-developed medial pterygoid tubercle, a retromolar space, and an asymmetrical mandibular notch in the Xujiayao 14 mandibular ramus are typical characteristics of Neanderthals (Wu et al., 2012; Wu and Trinkaus, 2014). The morphology of the temporal labyrinth of Xujiayao 15 and the relative proportions of their anterior, posterior, and lateral canals are consistent with Neanderthal traits (Wu et al., 2014). Likewise, the Xujiayao teeth have some Neanderthal features (e.g., high degrees of shovel shape and labial convexity for anterior dentition and continuous distal trigonid crests in the molar teeth; Xing et al., 2015). However, several other features that are common to H. erectus and modern H. sapiens (Jia and Wei, 1976; Jia et al., 1979; Wu, 1980; Bae, 2010; Wu et al., 2012, 2013, 2014; Wu and Trinkaus, 2014; Xing et al., 2015) prevented studies from affiliating the Xujiayao hominin to the classic European Neanderthals.

The authors go on to discuss the evidence with reference to the Denisovans and comment: “it is possible that the Xujiayao hominins were early Denisovans, just as the Sima de los Huesos hominins were ancestral to Neanderthals in Europe. Furthermore, molar teeth of Xujiayao hominins (Xing et al., 2015) have massively flaring roots and relatively large and complex crowns (Fig. 3b), which are reminiscent of Denisovans (Sawyer et al., 2015). Our updated age of 370e260 ka for the Xujiayao hominins is also consistent with the time (~430 ka) when early Denisovans appeared and colonized eastern Eurasia.”

Not, withstanding, the new dates for the cultural levels of the site from Tu et al. (2015), their postulations have merit. It is entirely conceivable that the Xujiayao fossil remains represent Denisovans. Alternatively, and particularly unpalatably, to the Chinese, these fossils may represent eastern Neanderthals.

Other evidence

1. Taphonomic analysis of the non-hominin bone assemblage

A great many fossil bones generated by hominid hunting/scavenging activity. From Li; J.S.; et al. (2018): “The faunal assemblage recovered from Xujiayao includes 21 taxa and is dominated by equid remains (including Equus przewalskii and Equus hemionus; Jia et al., 1979). Taphonomic analyses show that Xujiayao hominins had primary access to high utility long bones”. In other words, the horses were mainly hunted not scavenged. This is an unusual assemblage for China. From Gao (2017): “Only a few localities (e.g. Xujiayao, Shanxi) provide evidence of intensive hunting practices; a circumstance very different than what has been documented in Pleistocene-age archaeological assemblages in Europe, the Americas, and Australia. These characteristics, of course, reflect the principal underlying living and subsistence strategies of populations that created them, namely adjusting behaviour to environmental circumstances, taking strategic advantage of available resources and seldom exploiting resources to exhaustion.”

2. Lithics

Again, from Gao et al.: “A recent study of 1765 artifacts unearthed at Xujiayao in 1977 indicates that the assemblage includes cores, flakes, retouched pieces, chunks and debris. Lithic raw materials were mainly quartzite and quartz pebbles selected from nearby riverbeds. Simple hard-hammer direct percussion was used for primary core reduction, and a certain number of discoidal and polyhedral cores were left behind. About half the of the retouched pieces are small side scrapers made on flake blanks and spheroids constitute 27% of the assemblage, a very distinctive characteristic of the Xujiayao assemblage. Other tool types include points, notches, denticulates, chopper-chopping tools, burins and drills. Some bone tools have been identified. Because of the large number of horse and rhinoceros bones and artifacts recovered, particularly stone spheroids and bone tools, Xujiayao has been interpreted as a horse kill site.”

From Dani et al. (1994) “The Xujiayao stone spheroids are of particular interest. They may be divided into three categories according to size. It is thought that they may have been used as bolas or missile stones.”

Discussion

The morphological features of the temporal bone, mandible, ramus and dentition all show Neanderthal traits. In other words, EVERY skeletal element recovered, so far from Xujiayao has Neanderthal traits.

Add to this the unusual bone accumulation produced by horse hunting – a rarity in china where these kill sites are extremely rare as opposed to Neanderthal inhabited Europe where they are much, more frequent.  Add again the unusual projectile weaponry these hominids, presumably, used to bring down their prey and one is forced to conclude that whoever these ancestors of ours were, they are a distinct population, with unusual physical and cultural aspects to consider.

Were the Xujiayao hominids Neanderthals or some other hominids? Were they indeed Denisovans, the sister group to Neanderthals and thus shared some of their skeletal, morphological traits? Or were they what the what the Chinese like to refer to as archaic Homo sapiens with some traits gained via hybridisation from Neanderthals? All of these, are possibilities.

5. Jinsitai Cave, Inner Mongolia, China

Jinsitai Cave is a site in Inner Mongolia, China without diagnostic Neanderthal fossils or soil DNA traces of their presence. What it does have are Mousterian tools. Except for a few instances of use by anatomically modern humans, this technology is almost entirely used by Neanderthal, hence the inclusion of the site in this review.

The cave is well situated at 1401m above sea level, with a fine outlook over the low foothills of the Donghaierhan Mountains, 25 km west of the town of Alatanheli, Dongwuzhumuqin Banner, Inner Mongolia, North China. The cave, is situated in a granite hill and has an area of approximately 120m².

Li et al. Fig 1. Original caption reads: a) Geographical location of Jinsitai (JST) Cave. Neanderthal and Mousterian sites in Central Asia and Siberia are marked on the map, as well as early modern human sites in China. 2 = Denisova, 3 = Okladnikov, 4 = Chagyrskaya, 5 = Obi-Rakhmat, 6 = Teshik-Tash, 7 = Zhiren, 8 = Fuyan, 9 = Tianyuan. The red stippled line circumscribes the area with known Neanderthals associating with Mousterian industries. b) View of the entrance to JST Cave.

Initial excavations in 2000 and again in 2001, by a joint team from the Inner Mongolia Institute of Cultural Relics and Archaeology, Jilin University, Xilin Gol League Cultural Relics Station and Cultural Relics Administration of East Wuzhumuqin Banner, revealed the multiple culture layers of Bronze Age, Neolithic and Palaeolithic Age. The rich finds included evidence of cooking fires, stone tools and animal fossils, from Palaeolithic period. Whilst cultural remains were recovered from 8 layers also included bone tools, beads and charcoal samples for C14 dating the excavation was not particularly systematic, with records of the finds limited to stratigraphic level only. Crucially no grid system was set up.

Excavation at Jinsitai Cave from Lang (2013).

Lithic assemblage from Jinsitai Cave from Lang (2013).

Eventually, news of the finds spread more widely within China and the cave was re-excavated in 2012 by more senior scientists from the Chinese Academy of Sciences, Institute of Vertebrate Palaeontology and Palaeoanthropology (IVPP) Beijing, led by Feng Li.

From the Li, et al. (2018) abstract:

“The dispersal of Neanderthals and their genetic and cultural interactions with anatomically modern humans and other hominin populations in Eurasia are critical issues in human evolution research. Neither Neanderthal fossils nor typical Mousterian assemblages have been reported in East Asia to date.

Here we report on artifact assemblages comparable to western Eurasian Middle Paleolithic (Mousterian) at Jinsitai, a cave site in North China. The lithic industry at Jinsitai appeared at least 47e42 ka and persisted until around 40e37 ka. These findings expand the geographic range of the Mousterian-like industries at least 2000 km further to the east than what has been previously recognized. This discovery supplies a missing part of the picture of Middle Paleolithic distribution in Eurasia and also demonstrates the makers' capacity to adapt to diverse geographic regions and habitats of Eurasia.”

Lithics collected 2012-2013 from Jinsitai Cave from Li et al. (2018) figure 4.

Original caption reads:

Photographs of stone artifacts from layers 8 and 7 of Jinsitai Cave. 1, 3, 4) Levallois points; 2) Levallois flake; 5, 6) Transverse scrapers; 7) Dejete scraper. 1 and 2 from layer 7, 3-7 from layer 8. Orientation and direction of the blanks are indicated for retouched tools (5-7).

Dating

A total of 27 charcoal and bone samples were collected from the lowest cultural levels, namely levels 7 and 8. These were subjected to C14 testing. Many of the charcoal samples were of much younger ages than the bone samples. As no indication of the use of fire were found in either of these levels, the authors concluded that the minute flecks of charcoal collected were intrusive from levels 5 and 6 as these levels had a fireplace and a concentration of ash. Additionally, the dates from charcoal from these areas matched that of the minute flakes from layer 7 and 8. For this reason, the charcoal dates were discarded.

Dates on bone from level 8 were 44,289 to 42,306 cal. yr BP, whilst those from level 7 were 40,286 to 38,664 cal. yr BP.

Discussion

Despite it being a slightly heretical statement for Chinese scientists to express, they make a direct link to Neanderthal occupation near the end of their paper:

“The discoveries at Jinsitai supply a missing part of the picture of Middle Paleolithic distribution in Eurasia. The Jinsitai assemblages resemble the ‘Sibiryachikha’ Mousterian in the Altai Mountains of Siberia, and probably together represent a regional Mousterian variant in Northeast Asia. The presence at Jinsitai of assemblages that so closely resemble the late Mousterian assemblages from several parts of western and central Eurasia expands the geographic range of this package of lithic technological traits at least 2000 km further to the east.

Theoretically, one may argue that the features of the Jinsitai assemblages could be the result of

convergent evolution or continuous development from local lithic industries in North China. However, the existence of the whole suite of features, with few or no clear antecedents in the local area, weighs against this hypothesis. The contemporaneous late Middle and early Late Pleistocene assemblages from China lack the distinctive Mousterian-like features of the Jinsitai assemblages. A much more reasonable interpretation is that the Jinsitai industry is a result of population dispersal or technological diffusion from the Altai Mountains of Siberia, where populations making similar artifact assemblages existed earlier.

Associating lithic assemblages with hominin taxa is always a probabilistic and problematic endeavour. Although early AMHs are found with Mousterian assemblages in North Africa and Levant, Neanderthal remains are associated with classic Mousterian industries at dozens of sites in Europe, the Caucasus, and Central Asia. Mousterian industries from sites in the Siberian Altai are exclusively associated with Neanderthals based on genetic and/or morphological analyses of the human fossils. This increases the likelihood that the Mousterian industry at Jinsitai was also produced by Neanderthals or hominins with Neanderthal ancestry,..”

The DNA evidence

Comparison of Neanderthal and human DNA really, began with a paper by Green et al. (2010).

A detailed analysis of a draft Neanderthal genome and five low-coverage (4×) human sequences estimated that Neanderthals made a 1–4% contribution to the gene pool of modern non-African population. The presence of “Neanderthal DNA” in East Asians and Melanesians was initially surprising because the archaeological record shows that Neanderthals and early modern humans coexisted only in Europe and western Asia. Green and colleagues hypothesized that Neanderthals and modern humans came into contact and interbred in the Middle East ∼50–80 KYA, prior to the divergence of modern-day European and Asian populations.

There evidence was: First, they found that the three sampled non-African genome sequences (from a French, a Han Chinese, and a Papua New Guinean) are more similar to the Neanderthal sequence than is either of the two sampled African sequences (from a San and a Yoruban).

Second, they identified several haplotypes that are in low frequency in Europeans, absent from Africans, and present in the Neanderthal sequence, which suggests those haplotypes were derived from Neanderthals.

Third, they found many more genomic fragments in a European genome than in an African genome that have low divergence to the Neanderthal genome.

The research continued. I have quoted sections, directly from the papers concerned, to show its progress:

Wall, et al. (2013)

“We also confirm the conclusions of Yang et al. and Sankararaman et al. that the similarity of both Europeans and East Asians to Neanderthals is the result of recent admixture and not ancient population subdivision. Finally, we used the high-coverage Denisova sequence of Meyer et al. to determine that the admixture rate (f) into East Asians is ∼40% higher than into Europeans. “Neanderthal haplotypes” were at higher frequency in the East Asians than in the Europeans (9.6% vs.6.4%).

Our results and those of Meyer et al. imply that the relatively simple admixture scenario proposed by Green et al.  needs to be altered. At least two separate episodes of admixture between Neanderthals and modern humans must have occurred, and at least one of those episodes must have occurred after the separation of the ancestors of modern Europeans and East Asians. Rather than have two distinct episodes of admixture, it seems more plausible that admixture took place over a protracted period 50–80 KYA. During that period the ancestors of Europeans diverged and subsequently experienced less admixture than the ancestors of East Asians.”

Vernot and Akey (2015).

“In summary, by focusing on putatively neutral regions of the genome, we have shown that the observed patterns of Neandertal ancestry in Europeans and East Asians are not consistent with a simple one-pulse model of admixture. Thus, differences in the efficiency of purifying selection among populations are unlikely to account for higher levels of Neandertal ancestry in East Asians than in Europeans.”

Kim and Lohmueller (2015)

“In sum, our simulations suggest that across a wide range of biologically realistic models, a single pulse of Neandertal admixture, combined with the reduced efficacy of purifying selection against weakly deleterious alleles in East Asians, cannot explain the R values observed in empirical data. Instead, more complex demographic scenarios, possibly including an additional pulse or wave of Neandertal admixture into East Asian populations, must be invoked. Such two-pulse models have been shown to fit the observed data, better than the single-pulse-with-migration model, even when only the genomic regions most likely to be neutrally evolving are considered.25 In our simulations, across a range of different values for the strength of selection acting on Neandertal ancestry, a two-pulse model with realistic admixture proportions, 25 could generate the R values observed in the actual data, suggesting that such a model is the one viable explanation for differential patterns of Neandertal ancestry between East Asian and European populations.”

The key points to take from these papers are:

• Neanderthal remains are concentrated in Europe and as far east as central Asia (Russian Altai
• Neanderthals and humans interbred at approximately 50-80Kya, just after the Out of Africa event
• People in East Asia carry 15 to 30% more Neanderthal DNA than Europeans, this must mean the ancestors of East Asians interbred for a second after their split from the ancestors of Europeans, possibly in Central Asia
• It suggests Neanderthals spread far further east than originally thought
• Some authors have postulated that Neanderthals in the East Asia may have outlived those in Europe

Conclusion

We can summarise the evidence from these 5 sites and the DNA evidence thus:

1. Neanderthal occupation is definitively known from the Russian Altai, but their earliest occurrence in the region is ca. 110,000BP.

2. The Salkhit skullcap exhibits some Neanderthal traits and is dated, approximately mid-Pleistocene. As such it may represent a proto-Neanderthal or their direct ancestor Homo heidelbergensis.

3. ‘Hetao man’ - the scapula and parietal from the edge of the Ordos plateau, Inner Mongolia, China, date to about 70,000-125,000BP (maximum range 55-140ka) and 30,000-50,000BP respectively and both have Neanderthal features.

4. The array of hominid fossils, from Xujiayao in China, all exhibit Neanderthal features. The temporal bone, in particular, being, morphologically indistinguishable from classic, European Neanderthals. Some external features of this specimen, however are not in accordance with Neanderthal metrics.

This site is also notable for accumulation of Equus and other mammalian bones found, which indicated a kill site.

The significant element of the type of lithics found, namely the spheroids seem to indicate a unique hunting technique was used. All this evidence taken together strongly indicate that a community of hominins, possibly Neanderthal or with Neanderthal ancestry lived in this part of China at ca. 250,000BP.

5. The lithics from Jinsitai Cave are unequivocally Mousterian. Dated to approximately 43,000BP they are however too late to support the hypothesis that Neanderthals were in Southern California 130,000BP.

6. The DNA evidence, however, may suggest that, Neanderthals spread far further east than originally thought

Taking all the evidence into account, it seems that if Neanderthals were in the Americas at a date in accordance with that established by Holen et al. (2017), they must have been Early or proto-Neanderthals with features inherited from their ancestors, Homo heidelbergensis.

If so, are they really, Neanderthals? Perhaps we should consider that, although this lineage may have made it to America prior to 130,000 years ago we should define them differently? Perhaps Archaic Homo sapiens or as the rest of the scientific community defines them Homo heidelbergensis were the hominins that were the first in America?

Whatever the case, it seems unlikely that Neanderthals in the classic sense whether from Europe or the Altai were the hominins in Southern California 130,000BP.

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