New horizons on the knowledge of the population during the Middle/Late Pleistocene.
The human remains of
Guattari Cave (S. Felice Circeo, Lt, Italy)

doi:10.21203/rs.3.rs-4158900/v1

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New horizons on the knowledge of the population during the Middle/Late Pleistocene. The human remains of
Guattari Cave (S. Felice Circeo, Lt, Italy)

https://doi.org/10.21203/rs.3.rs-4158900/v1

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Along the coast of southern Lazio (central Tyrrhenian Sea) there is a significant series of multilayered coastal caves, most of which provide abundant evidence of occupation during the Neanderthal time horizon. In one of these caves, Guattari cave an extraordinary discovery of hominin remains dating back to approximately 66-65ka was made in 2019-2022, which places the Guattari cave finds in a specific period within the Neanderthal population of the Italian peninsula. Ongoing studies have demonstrated the presence of a particular morpho-anatomical variability in the population that lived in the Circeo area with plesio- and apomorphic characteristics that could open new evolutionary horizons. Biological variability and affinities that would suggest rather complex unexpected population dispersal scenarios. The particularity of these finds, chronologically very close, allows us to consider Guattari cave as one of the most important sites for the study of the Mediterranean area during the middle and late Pleistocene. We have studied the new finds and the morphology, compared to Circeo1 skull, aligns more with Javanese H. erectus than with Neanderthals. A discovery that identifies this region as a focal point of coexistence of different lineages, H. erectus s.s., H. erectus s.l., proto-Neanderthal, "classical" Neanderthal, and H. sapiens, which could define new and unexpected migratory and evolutionary dynamics towards modern humanity. In a Neanderthal context, such as that of Circeo, the presence of fossil human evidence documenting a mosaic model consisting of a Javanese H. erectus paleodeme associated with primitive and unusual characters could represent the result of a hybridization between archaic and modern humans and a phenomenon of dispersal into Southeast Asia and Australo-Melanesian.

Biological sciences/Evolution/Anthropology/Biological anthropology

Biological sciences/Evolution/Anthropology/Archaeology

Homo erectus

Neanderthal

MIS 4

central Italy

Southeast Asia

1.1 Human variability in the Pleistocene on the Circeo promontory

The Tyrrhenian coast of Lazio (central Italy) is characterized by numerous caves between the Circeo and Gaeta promontories (Fig.1.1), many of which show traces of human presence, but only three of which contain human remains (Fossellone cave, Breuil cave, and Guattari cave). Guattari cave opens about a hundred meters from the coast of the Tyrrhenian Sea, on the eastern side of the Circeo promontory. In the first half of the last century, a complete skull (Circeo1) and two mandibles of Neanderthals (Circeo2 and Circeo3) were accidentally found there^1,2. Late archaeological excavations between 2019 and 2022 brought to light another 15 human finds, an extraordinary record in Italian studies on the Middle Pleistocene and in European paleoanthropological documentation. In late years, great strides have been made in understanding final Pleistocene society. Greater accuracy in dating and paleoenvironmental, paleoecological and genetic reconstructions has made it possible to better understand the movements and contacts between populations of the middle and late Pleistocene, highlighting very interesting aspects for human evolution. Neanderthals lived in Eurasia together with Homo erectus, Homo heidelbergensis, the Denisovans (Altai and Meridional Siberians³) and finally Homo sapiens, as well as other perhaps unknown species. Certainly, there were also genetic interactions with areas of East Asia through populations such as Homo luzonensis, Homo floresiensis and the controversial Homo longi. Late studies have revealed that the morphology and evolutionary patterns of late Pleistocene humans in East Asia has been a source of remarkable new insights into the origin, evolution, and interaction of modern humans⁴. Molecular biology has allowed the reconstruction of some complete genomes of Neanderthals and the Denisovan sister sample which have shed light on important migratory aspects^{5,6,7,8,9,10, 11,12,13}. Throughout their long history, Neanderthals, like all contemporary human groups, have faced sudden climatic and environmental changes^14,15,16 and have always found the way of adapting to them, especially thanks to their profound knowledge of the environment. Seeking areas with favorable climatic and feeding conditions, they spread across Eurasia, from Gibraltar to the Altai Mountains and from the Middle East to Britain and the Mediterranean Sea. In relation to the Middle Paleolithic, on the Tyrrhenian coast of the Italian peninsula there are numerous rock shelters and caves, a sort of ecological refuges from the harsh climate of the ice ages, with multilayered archaeological deposits containing evidence of Neanderthal activity made up of paleosites with Mustérian industry (e.g.^{1,17,18,19,20,21}). Despite the abundance of archaeological and faunal remains found on many of these Italian coasts, paleoanthropological remains are extremely rare²². In this light, the discoveries in one of these sites, Guattari cave, are of exceptional value not only for the richness of hominin remains but above all because they can sample more than one taxon. The study of fossils from late excavations, contemporary with the first discoveries (C1, C2 and C3) and therefore always assignable to the same time horizon as Neanderthals, highlights a morphology that does not perfectly adapt to what defines a classic Neanderthal. A morphology consisting of a mosaic of primitive and derived features documented in H. erectus sensu stricto(s.s.), late H. erectus of Southeast Asia [H. erectus sensu lato(s.l.)], Neanderthals and H. sapiens. This high variability, in an unexpected context as it is geographically very distant from south-eastern Asia, allows us to outline a new geographical model defined by unexpected migratory dynamics. The new discoveries and subsequent studies could, therefore, allow us to better understand the migratory movements that occurred in Europe and Asia during the middle and especially late Pleistocene by re-evaluating the position of the last Asian Erectus in south-east Asia. The presence of Homo neandertalensis is well documented in Eurasia, however, the taxonomic attribution of the majority of these last Circeo specimens to H. neanderthal is rather controversial but of particular importance regarding the geographical and genetic migratory dynamics that involved the populations Eurasians in the final phase of the Pleistocene including the first Sapiens.

1.2. Historical investigations

The entrance to the Guattari cave opens at about 7 m above sea level on the eastern slopes of Monte Morrone, a low hill on the slopes of the Circeo promontory (Fig.1.1 and 1.2). The cave was discovered by chance on February 24, 1939, during construction work. The owner of the site, A. Guattari, and some workers found the Neanderthal skull (C1), in an internal space later called "Antro dell’Uomo" ^1,23,24. The skull rested on the paleo-surface of the cave which was covered with an abundance of fossil animal bones and concretion fragments (Supplementary, Fig. S1A and B). Shortly afterwards, the skull was joined by the discovery of a Neanderthal Circeo II mandible (C2)²⁵, perhaps belonging to the same individual, found a few tens of centimeters from an employee of A. Guattari. A second mandible, also Neanderthal, Circeo III (C3)²⁶was finally found much later, in 1950, outside the cave by G. Lacchei and V. Ascenzi. The subsequent inspection by the studious, who found part of the find still incorporated into the Pleistocene layer, allowed the stratigraphic positioning of the mandible (Fig.1.5). Segre²⁷, placed the human find near a deposit of ossiferous breccia still adhering to the rock face above the entrance to tunnel 1 (Fig. 1.5). The excavations of the site started at the same time as the first discovery continued more or less continuously until the 1950s and involved both the external and internal areas of the cave through the creation of several trenches (Fig.1.3). The first investigations of the 1930s and 1940s under the direction of A.C. Blanc, L. Cardini and A.G. Segre involved the excavation of two main trenches A and B (Fig. 1.3). A was carried out at the main entrance to the cavity (Tunnel 1) and oriented SE/NW, while B was carried out along the rocky ridge immediately NE of access tunnel 1 and oriented NE/SW. Trench B and the NW portion of trench A were then unified in 1950 into a single excavation area between the entrance and tunnel 3. Along this entire strip it seems that the excavations reached the Tyrrhenian fossil beach at the base of the Pleistocene sequence, deepening for more than a meter from the initial plane.

The characterization of the Pleistocene deposit of Circeo and the prehistoric site of the Guattari cave is clearly outlined already from the first historical excavation results from which it emerges:

I) that outside the cave, between the entrance and tunnel 3, a wide strip of beach with shells (warm species) was discovered

II) that the enlargement of trench A, near the opening, provided very little fossil material, suggesting the hypothesis that "the cave closed in A in a relatively ancient period, and instead remained accessible in B" (notes of Cardini's excavation 2 March 1939).

III) that the importance of the deposit in front of the cave was all in the quantity of lithic artifacts (lithic industry) that were found there and in the numerous well-preserved charcoals and splinters of burnt bones.

From these data it is clear the existence in the Guattari cave site of a first and oldest structured anthropic activity, consisting of burnt bone, charcoals, burnt soil fragments (hearths?) and lithic artefacts, in the atrial portion and in external area in front of the cave, with a greater involvement of the sector in front of B, and a second and much later hominine testimony documented however mainly by the sole presence of human skeletal remains, among the numerous fauna, in the internal area of the cave (“Antro dell’uomo” and “Antro del laghetto”). Recent investigations²⁸in the external area, which highlighted the remaining portion of trench B (NE), and in the internal area "Antro del laghetto", confirm what emerged (Fig. 1.3).

1.3 Late investigations

The “Antro del laghetto” area

The excavation data place the " Antro del laghetto" area (so called by A.C. Blanc in various contributions 1939, 1954, 1961) as the innermost area of the Guattari cave located in front of the "Antro dell’Uomo", where they were found, in February 1939, the Neanderthal skull (C1) and one of the two mandibles (C2) [Fig.1.3 and 1.4 and 1.5]. The “Antro del laghetto” area, as the name suggests, is distinguished from the other areas of the cave by the rise of the karst water table from October to May²⁸. The “Antro del laghetto” has a maximum length of 9.93 m and a reduced width, which varies from 3.6 m to 0.75 m in the internal area and has a minimum height between +5.52 m and +4.98 m above sea level (the nearby “Antro dell’Uomo” is between +5.91 and +5.97 m above sea level)²⁸. The excavation involved the deposit at a depth between 47 and 102 cm. 25 stratigraphic units (SUs) were found, which allowed the identification of four different levels with different geological and archaeological characteristics (Supplementary, Fig.S2). In the "Antro del laghetto" succession, the low overall number of lithic artifacts (28 lithic artifacts in level 3 and 7 in level 2) excludes a strong human presence inside the cave²⁸. Evidence of human activity is instead well documented in the most external^27,28and oldest deposits, characterized by abundant faunal remains, many of which were burnt, high concentration of charcoals (hearth?) and lithic industry^27,28 which geochronological data place between ∼121 ka and ∼105 ka²⁹.

1.4 Chronology

The general stratigraphy of the cave is summarized by Segre²⁷who divides the internal and external deposits into units of which the lowest one is made up of the beach fossil deposits (Fig. 1.5). The attribution of this deposit to MIS 5.5 was recently confirmed by the 40Ar/39Ar dating of the detrital sanidine extracted from the biodetritic deposit present at the base of the cave filling which returned an age of 121.5 ± 5, 8 ka²⁸^,29. While the basal age of the internal continental filling of the cave, obtained from a sample of the layer covering the basal marine deposit (Fig.1.3 and 1.5), provided two datings corresponding to 112.6±0.9 ka and 100.4 ±5.9 ka²⁸. Therefore, the entire internal continental clastic succession of the cave filling developed, between the age of the flow overlying the beach deposits, dated 112.2±1.0 ka-100.4±5.0 ka and before 59.9±0.8 ka, age of the oldest coralloid concretions^28,30.

According to Cremaschi et al.³¹ above the Tyrrhenian beach sands (unit 1, atrial portion of the cave and area in front of it) the sequence presents two distinct groups of stratigraphic units, both pertaining to an overall cold period following MIS 5.5. The first group of units cemented by several phases of calcite precipitation (subunits 2 base, 3A, 3B, and unit 5) contains archaeological materials (burnt bones, charcoal) and large quantities of carnivore-omnivore coprolites. All have undergone colluvial processes (i.e. solifluction), and thermoclastic phenomena compatible with a more humid cold environment. Even stronger diagenesis and modifications of the archaeological record have been envisaged in the second group of units (Units 7 and 8, atrial part of the cave). In this group the results grain size analysis is compatible with the presence of backline dunes outside the cave during cold-arid periods ³¹.

For the geochronology of the "Antro del laghetto", two stalagmites were selected within Level 2, with accumulation of human and animal bones, and two samples were taken of coralloid calcitic concretion which covers the upper surface of the “Antro dell’Uomo” ²⁸ (Figs.1.3 and 1.5, Supplementary, Fig.S2). The coralloid concretion taken from the skull of C1 (“Antro dell’Uomo”) was previously dated, with the isochronous U/Th method, by Schwarcz et al.³⁰.

The results date the middle-upper succession of the "Antro del laghetto" (Level 2) to ~66-65 ka (MIS 4), and the upper portion of the "Antro dell'Uomo" to a basal age of 59.17± 0.85 ka and at a maximum age of 51.1±1.2 ka²⁸(Fig.1.3 and 1.5, Supplementary, Fig.S2). Overall, the new results regarding the chronology of surface coralloid concretion agree relatively well with the earlier dating of ~57-50 Ka by Schwarcz et al.³⁰. The middle-upper part of the "Antro del laghetto", is chronologically delimited by four very concordant U/Th datings in the narrow time window of ~66-65 ka, during the Greenland Stadial (GS) 19.1^28,32, one of the most severe time intervals of the MIS 4 glacial stage. Extra-regionally (Puglia, Abruzzo and southern Italy) this short interval coincides with drier, open and arid conditions²⁸. In central Italy, speleothem growth rates in the Apuan Alps suggest temperatures below zero °C. However, it is interesting to underline that the regional paleoclimatic data during GS 19.1 diverge from the local paleoenvironmental (pollen and fauna) and paleoecological data which indicate the Circeo promontory as a cold open environment but at the same time made up of vegetation compatible with less severe climatic conditions²⁸. In summary, we can conclude that the stratigraphic sequence of Guattari cave was formed between MIS 5.5 and MIS 3, i.e. between the high Tyrrhenian marine relief (⁓125 ka BP) and the landslide that closes the cave, after 50 thousand BP³¹. Therefore, Guattari cave, like other coastal caves affected by the variability of sea-level oscillations, became accessible to man only starting from the end of MIS 5.5, around approximately 120 ka³³. The human remains of the Guattari cave and other sites in the Monte Circeo area (e.g. Breuil cave, Fossellone cave) are attributed to the Middle-Late Pleniglacial, i.e. MIS 4 and MIS 3²⁸.

1.5 The discovery of human remains and possible migration scenarios and dispersion models

The late excavations (2019-2022) which involved the “Antro del laghetto” area have brought to light numerous humans remains within a large sample of fauna. The total number of human fossils remains, first and second discoveries, consist of 15 cranial and postcranial finds. The result of preliminary investigations regarding the minimum number of individuals identifies, on the basis of the number of cranial remains (including skull C1), the presence, within the sample, of at least four individuals (C1, C4, C5 and C8). The skeletal remains from the second discovery (2019-2022) include a fronto-parietal portion “Circeo 4” (C4), a calvarium “Circeo 5” (C5), a mandible incomplete “Circeo 6” (C6), a femoral diaphysis “Circeo 7” (C7), an occipital bone “Circeo 8” (C8), an incomplete maxillary “Circeo 9 ” (C9), and finally a right coxal bone “Circeo 16 b” (C16b) and a left “Circeo 16 a” (C16a) incomplete and probably belonging to two different individuals female. The dental sample is made up of 7 teeth identified as: right M²-M³ with portion of alveolar bone of a single individual “Circeo 10 a-b” (C10 a-b); Right M₃ affected by hypercementosis “Circeo 11” (C11); ₃M left “Circeo 12” (C12); C¹ right “Circeo 13” (C13); Right P⁴ affected by hypercementosis “Circeo 14” (C14) and finally incomplete right M¹ “Circeo 15” (C15). The sample shows characters shared with a clade/taxon H. erectus s.s., in comparison with the holotype Trinil 2 (C5), proto-Neanderthal, “classical” Neanderthal (C1), Javanese H. erectus p-deme (Ngandong and H. luzonensis, most-advanced form of H. erectus) and archaic Middle Eastern Sapiens (Skhul/Qafzeh and Manot1). Therefore, the hypothesis of the existence of multiple paleodemes within the same site is outlined which finds support in the presence of variations in morphological detail that highlight distinct morphs/taxa³⁴. The first variant emerges from the direct comparison between the finds of 39 and 50 (C1 skull, C2 and C3 mandibles), classic Neanderthals, and the late finds (C4, C5, C8 and C6) characterized, in comparison with previous and contemporary human species, by a mixture of autapomorphic and symplesiomorphic traits shared with the monophyletic group (proto-Neanderthal and classical European Neanderthal, Erectus s.s. and s.l., and Sapiens). The same variability emerges from the dental sample.

In the frontal, anterior view, C4 and C5, they present a morphology shared with early European proto-Neanderthals such as Biache-Saint-Vaast 2 (BSV2) and with late European Erectus such as Lazaret 24 (170 Ka). In analogy with the late Indonesian Erectus, Ngandong 5, the supraorbital torus of C4 is continuous, has a discontinuous and not well-defined supratoral sulcus and the thickness of the bone, high as in C5, is closer to the Indonesian rather than Neanderthal canons. C5, a small calvarium, presents a mixture of proto-Neanderthal symplesiomorphic characters (e.g. the absence of the anterior mastoid tubercle) and Neanderthal (the digastric sulcus closed anteriorly), autapomorphic characters of a different taxon identifying a Javanese morph (H. erectus s.s. Trinil 2 morphotype and Javanese H. erectus p-deme) and finally a morphology of the parietals (vertical with a curvature starting in the upper third) very similar to the archaic Middle Eastern Sapiens Manot 1 (Israel). C5, like Trinil 2 and Sangiran, presents a frontal keeling accentuated by a pair of long anteroposterior depressions and a bregmatic eminence that does not extend bilaterally into the coronal keels or posteriorly into a sagittal keel, although a pair of small depressions are located posterior to the bregma³⁴. The frontal Keel, unlike the Ngandong sample, is not separated from the bregmatic eminence. The configuration of the mandibular fossa and the tympanic plate is instead similar to that of the Ngandong specimens and as in these specimens, and contrary to C1 skull, it does not present the styloid process fused with the petrous bone and does not present the postglenoid process. The coxal bones C16a and C16b present, contrary to Neanderthal canons, a single iliac buttress acetabolocristal (C16a), and acetabolspinal (C16b) as documented in the Middle Eastern archaic Sapiens group Skhul/Qafzeh (Israel).

As regards the dental sample, still under study, it is possible to anticipate the presence of a mosaic of characteristics made up of typically Neanderthal non-metric features (middle trigonid crest), modern features (simplified postcanine crown) and finally archaic features (vertical buccal sulcus) documented in the Middle Pleistocene but present in evolved H. erectus and Indonesian Sapiens. Specifically, we refer to a buccal vertical groove located on the C14 upper premolar as in H. luzonensis and H. sapiens (Dushan1) 15,000 years old in Southeast Asia^35,4. According to Liao et al.⁴, this trait is documented in Chinese H. erectus, Middle Pleistocene European hominins, H. erectus, and other later archaic Homo such as Xujiayao or in specimens of Australopithecus and early Homo. Among the various hypotheses put forward by the authors⁴, regarding the presence of this primitive trait in Dushan1, we consider of particular interest, as we will explain below, the hypothesis that would consider it the result of an introgression of some archaic populations that survived late in the region. On the basis of what has been said above it is possible to formulate evaluations and interpretative hypotheses regarding the possible evolutionary relationships and migratory dynamics of the hominins that populated Eurasia in the final Pleistocene. Throughout the Pleistocene, Java was relatively isolated from the Asian mainland in the cyclical succession of glacial and interglacial phases³⁶. This relative isolation could have translated into an alternation of favorable and unfavorable conditions for overcoming geographical barriers in the process of human evolution in an insular and consequently continental context. Therefore, as claimed by Zanolli et al.³⁷, if it is possible that a group of hominins (at least two species, H. erectus and H. floresiensis) reached the Philippines via land bridges (Sonda-Palawan-Luzon) in the glacial phases of the lower and middle Pleistocene, it is equally possible that a reverse event occurred, i.e. migrations that undertook paths with trajectories that extended from the regions of south-east Asia to continental Asia up to Europe. The evidence of human attendance at Guattari cave in a chronological span between 120Ka and 66Ka would seem to almost overlap with the period of attendance by the Javanese Homo erectus in the Luzon Island (50-66.7 ± 1 ka³⁵) and Ngandong (117,000–108,000 Ka³⁸). The chrono-morphological similarities between this Indonesian human sample and that of Circeo and the presence in both of unique characters documented in H. erectus s.s. and s.l. and primitive characters also documented in the European hominin of the Middle Pleistocene could open up new migratory scenarios and define new evolutionary and dispersal models (Fig. 2):

Scenario 1. Late Homo erectus may not have become extinct in Ngandong³⁸ and the archaic Sapiens hominins Skhul/Qafzeh may not represent an extinct lineage³⁹.

Based on the chronological data relating to the Ngandong group (117-108 ka,³⁸) and the Skhul/Qafzeh (Israel) group (92± 5 Ka and 80-120 Ka⁴⁰) the finds humans from Circeo could testify to the presence of Javanese H. erectus p-deme and Middle Eastern archaic Sapiens (Israel) on the European continent and validate the hypothesis of a contact which occurred during a first (I) dispersal from Asia→Europe. A contact already documented at Tam Ngu Hao 2⁴¹, between Erectus-southern Neanderthals/Denisova (genetic evidence shows the eastward dispersal of Neanderthals in the Russian Altai in the late Pleistocene) and Sapiens in the mid-late Pleistocene, thus expanding the geographical boundaries to new migratory dynamics which also see Europe (Italy) involved with Asia and South-East Asia.

Scenario 2. If the datings are exact, the slight chronological difference between the Circeo remains (about 66-65 Ka) and the Luzon remains (50-67 Ka,³⁷) and Manot 1 (54.7 ± 5.5 ka⁴²) would allow us to hypothesize, in this final period, a hybridization process in Europe (Italian peninsula) with a subsequent phenomenon of dispersal (II dispersal) towards Western Asia and south-eastern Asia.

We hypothesize a hybridization process within this context precisely due to the presence of the high variability found within the Guattari cave sample which features, in a final phase of the Pleistocene, a classic Neanderthal morph (C1, C2 and C3), and morph/taxa distinguished from this by the presence of a mixture of morphological and metric characters (dimensions but above all thicknesses) which have outlined a mosaic model which could represent the result of a cross between proto-Neanderthal and Classical Neanderthal (meridional Denisova), Erectus s.s., Erectus s.l. (late Javanese and European) and early Sapiens. Hybrid skeletons of extant primates tend to show an increase or decrease in size (heterosis and dysgenesis), and hybrid populations are characterized by high degrees of individual variability⁴³.The hypothesis of this scenario indicates, for the final Pleistocene, the presence of complex demographic models, with the possible survival of archaic populations, hybridizations and migratory and dispersion processes from Europe towards South-East Asia and vice-versa. Movements and genetic flows probably linked to the severe glacial climatic conditions (MIS 4) documented for this period, which at the same time would have favored geographical connections through land bridges³⁷.

Scenario 3. Excluding the hypotheses of scenarios 1 and 2, it is however certain that the mosaic of primitive and derived characters that emerged on the human sample from Circeo documents the evidence of contact between different clade/taxon. A contact which, even if it did not occur exactly in this context, must nevertheless have occurred, in the first half of the late Pleistocene (I and II dispersal), along the trajectory between Europe and south-eastern Asia. A vast geographical area which has already lately been placed at the center of attention by molecular studies and whose results have opened up new interpretative fronts regarding the migratory and evolutionary dynamics, with crossbreeding and genetic flows, which led these populations of the final Pleistocene to modern humanity. The genetic results confirm, in fact, the presence of gene flows between these continental and insular populations of south-east Asia, Denisovans and Neanderthals, results which have allowed us to hypothesize the presence of various migratory waves in the late Pleistocene whose modalities still remain unknown^{44, 45,7, 46, 47, 48, 49}.

Genetic studies on ancient and modern mitochondrial DNA (mtDNA) have documented the existence of important Eurasian population turnover in the late Pleistocene. From the results of these studies, it emerges that all current non-Africans belong to two basal mtDNA haplogroups (hgs), M and N⁵⁰. The M lineage is absent in contemporary Europeans, but is present with high frequency in modern Asians, Australians, and Native Americans⁵¹. In the analysis of 55 European mitochondrial genomes, researchers⁵² identified the presence of the M lineage (mtDNA) in individuals preceding the last Glacial Maximum, a discovery that offers relevant implications on the timing of dispersal of modern humans in Eurasia⁵² including, potentially, the Circeo sample. The time to the most late common ancestor of each of these two clades was estimated independently at ~50 ka (95% confidence interval [CI], 53-46 ka) and at ~59 ka (95% CI, 64- 54 ka), respectively⁵³, a time surprisingly very close to the chronology estimated for Guattari Cave and almost overlapping with that of Luzon. This time range was later narrowed⁵² to between 44 to 55 ka which coincides with the presence of the first modern humans in Australia and Europe⁵². The interpretation of these results has been read as: i) evidence of an early spread of modern humans, hg M, to Asia via a probable southern route followed by a subsequent spread, hg N, via a northern route⁵⁴; ii) evidence of a unique pattern of Eurasian dispersal that first reached Asia and then western Eurasia after the loss of hg M⁵⁵,iii) evidence of a unique, late and therefore rapid dispersal of a population originally containing both M and N hgs and which contributed to all the mitochondrial diversity of current non-Africans⁵¹. The authors⁵²attribute the loss of hg M to demographic dynamics that occurred subsequently within Europe itself. The expansion therefore occurred before the diversification of M and N, with subsequent migration bringing both lineages to Europe⁵². The results of this study⁵²confirm what emerged from our results by providing genetic confirmation (mtDNA) to the existence of contacts and crossings between lineages, diachronic and synronic, very distant geographically. Specifically, the expansion models of the final phases of the Pleistocene proposed by Posth et al.⁵² are in line with the models (scenario 1 and 2) that emerged from our analysis which predicts a first and oldest Asia→Europe dispersal of basal haplogroups M and N, with a loss of M probably due to the presence of numerous lineages in Eurasia, but found in the mtDNA of Belgium and France⁵², and a hybridization followed by a second late and rapid dispersal Europe→Asia→Southeast Asia, where pre-existed M, and where lineage is present with high frequency in modern Asians and Australians. Genomic evidence, therefore, which documents with certainty the existence of migratory and evolutionary dynamics, in the late Pleistocene, and above all the existence, in Eurasia, of gene flows capable of covering large latitudes and overcoming geographical barriers extending to the island areas of Southeast Asia. The morphometric diversity found in the Circeo sample could therefore explain the genetic diversity of the first modern humans who spread to Europe during the late Pleistocene.

1.6 Objectives of the study

We present the morphometric study and the phyletic position of unpublished finds from the Neanderthal site of Guattari cave which represent the result of late excavations (2019-2022) defining both the chronostratigraphic context of the site, already emerged in 1939, but above all expanding the paleodeomographic framework of the promontory of the Circeo of the middle and final Pleistocene. To establish the phyletic relationships within this human sample we carried out qualitative analyses, exploring the morphological variations, and quantitative metrics by comparing these data with those, synchronic and diachronic, available for African, European, Asian Homo (with particular attention to the area south-eastern) and modern. The detailed morphological model that emerged shows diversity with evolutionary implications of the terminal hominins of the Eurasian Pleistocene which require further investigation as they could contribute to defining new geographical and phylogenetic pathways.

2.1 The stratigraphic excavation of the “Antro del laghetto”.

The excavation was carried out from October 2019 to May 2022, with a forced break between March and May 2020 due to the health emergency of Covid-19. The cyclic presence of groundwater did not allow a continuous and comprehensive excavation of the paleosurface. The deposit was examined using stratigraphic units (SUs) that allow identification of different archeological and geological levels²⁸ (Supplementary, Fig. S2).

The fauna consists of the red deer (Cervus elaphus), which is the dominant species, followed by the spotted hyena (C. crocuta) and the aurochs (B. primigenius). Other identified species include wild horse (E. ferus) and wild boar (Sus scrofa), rare fallow deer (Dama dama), two bear species (Ursus spelaeus and U. arctos), a few remains of a rhinoceros species (probably Stephanorhinus hemitoechus), abundant giant deer (the Irish elk, Megaloceros giganteus) that have never identified before, rare elephant (Palaeoloxodon antiquus) and hippopotamus (Hippopotamus amphibius), roe deer (Capreolus capreolus), leopard (Panthera pardus), ibex (Capra ibex), chamois (Rupicapra sp.), cave lion (Panthera spelaea), wild cat (Felis silvestris), and European hemione (E. hydruntinus), which have also never been identified before, hare (Lepus sp.), fox (Vulpes vulpes), wolf (Canis lupus), and at least one mustelid in addition to sparse birds and micromammals²⁸^,56. The lithic industry is a regional variant of the Mousterian technique, known as the Pontinian technique¹.

The hominin remains are stored in the Anthropological Service of the Superintendence of Archeology, Art and Landscape for the provinces of Frosinone and Latina.

The new human remains of Guattari Cave (II discovery) are described and compared with the human remains from 1939/1950 (I discovery) and with a large sample of diachronic and synchronic Homo fossils from the Pleistocene (Supplementary, Table S1) distributed over different geographical areas (Europe, Africa and Asia) to evaluate their phenetic affinitiese and evolutionary relationships. For comparison analyses linear measurements and thicknesses were taken (Supplementary, Tables, S2-S9) and the presence/absence of non-metric morphological characters was detected (Table1).

The skeletal measurements of the hominins were taken following the suggestions of Martin⁵⁷, the metric data of the teeth were recorded for the buccolingual and mesiodistal crown dimensions following the protocol of Hillson⁵⁸, the morphological features of the teeth were observed using the ASUDAS method of the Arizona State University Dental Anthropology System⁵⁹.

Paleogenetic analysis have been carried out in Leipzig and Vienna, highlighting such a scarcity of collagen that it was not possible to extract aDNA (Supplementary Data)

2.1 Materials

Fossil finds from 1939: Circeo 1 (C1 - skull), Circeo II (C2 - mandible), CirceoIII (C3 - mandible).

Late excavations (2019-2022): “Antro del laghetto” area have brought to light numerous humans remains within a large sample of fauna. The human sample consists of a total of15 finds, made up of districts and anatomical parts. Preliminary analyzes of the finds have currently revealed the presence of at least four individuals (including Circeo1 skull), with the skull serving as the lead district. The sample shows Erectus and Neanderthal autapomorphies.

Cranium

Circeo 4 (C4)

Fossil find found inside the cave, “Antro del laghetto” area (Figs. 1.3, 3A and Supplementary, Fig. S3).

Portion of calvarium composed of 4 elements constituting a large part of the frontal bone and a small part of the left parietal bone. The frontal bone consists of a right and a left squama frontalis. In the frontal profile, the medial region is receding and the sulcus supratoralis is light and discontinuous as it is interrupted, in the gabellar region, by a median post-toral convexity probably accentuated by the pneumatization of the frontal sinus. In the frontal view, the post-toral convexity could mimic a frontal keel even if a decentred localization with respect to the frontal sagittal line is evident. There is mild asymmetric retro-orbital narrowing. The supraorbital torus is thick (Supplementary, Tables S5, S7) and the prominent glabella is in line with the nasion. The orbits are rounded, and the dimensions of the superior orbital cavity are height ⁓ 18.2mm and length ⁓ 33.2mm. The height of the torus (highest point 18.7mm) remains more or less unchanged from the medial region (15.8mm) to the lateral one (15.4mm). The supraorbital arches are incomplete, exposing part of the frontal sinus. This appears to be made up of several asymmetrical chambers (at least 6 or 7 can be distinguished) separated by intrasinus bony septa. Each sinus extends superiorly to the medial end of the supraorbital torus and back into the orbital portion of the frontal bone. The three right chambers are separated by vertically and horizontally oriented bony septa. The dimensions (mm) of the three upper, lower and lateral chambers are respectively: 6.6x9.7, 8.5x8.2 and 10.9x14. The fourth middle-central chamber, with dimensions of 32.1x24.3, seems to merge with the left sinus. The latter is larger and consists of three chambers separated by septa, of which the central, larger one is separated from the right sinus by a septum oriented to the right. The dimensions (mm) of the three upper, lower, and lateral chambers are respectively: 11.2x20.8 with a depth of 20.1; 6.4x8.0 and 8.6x18.3. The left lateral recess extends and reaches approximately the middle of the left supraorbital torus. The upper part of the left middle-central chamber extends to the supraratoral sulcus and its pneumatization determines the extracranial convexity which interrupts the straight path of the supratoralis sulcus.

On the internal wall of the middle-central chamber, a foramen (4.4x3.4mm) with rounded margins is visible followed by a canal that extends at least for approximately 5.2 mm in depth. The absence of surrounding alterations and a localization near the internal frontal crest associated with a vascular morphology do not exclude the existence of a possible relationship with the Superior Sagittal Sinus (SSS). Despite the strong extracranial cortical erosion, a short section of coronal suture on the left frontal squama remains preserved (Supplementary, Fig. S4), a relevant data not only from a metric point of view but also from a diagnostic point of view as it allows us to formulate an approximate age diagnosis. The individual, therefore, according to modern parameters, could be an adult, but not too much, considering the persistence of sutural denticles. The morphology and total frontal bone thickness (total thickness of the diploe and of the inner and outer tables) are, like the C5 calvarium, not compatible with C1, an aspect that could possibly depend on an intraspecific variability of species rather than genus.

Circeo 5 (C5)

Calvarium fossil found inside the cave, “Antro del laghetto” (Figs.1.3, 3B and B1, Supplementary, Fig. S5)

The neurocranium displays derived (autapomorphic) and primitive (symplesiomorphic) features. The morphological traits indicate an adult female individual.

Morphological analysis

The squama frontalis has a distinct post-toral plane and a high, rounded frontal. The supratoral sulcus is continuous and the supraorbital torus is thick (Supplementary, Tables S5, S7) The glabella is in line with the nasion. The orbits are rounded, and the dimensions of the superior orbital cavity are height ⁓20.7mm and length⁓ 42.9mm. The height of the torus (highest point ⁓ 21.2mm) decreases from the medial region (14.7mm) in a lateral direction (11.4mm→10.4mm). There is a slight supraorbital narrowing and residual traces of the lower part of the metopic suture. It has a frontal (metopic) keel that extends for much of the sagittal line, and which as in Trinil 2 holotype (autapomorphy), is defined by a pair of long and mediolaterally wide antero-posterior depressions in the frontal squama^60,34 (Extended Data, Fig.1, Supplementary, Fig.S5A and B). It presents a well-developed bregmatic eminence, associated with two pre-bregmatic parasagittal depressions that do not involve the parietal bone (Extended Data, Fig.1, Supplementary, Fig.S5D). The bregmatic eminence is not separated from the frontal keel. The Calvarium is moderately elongated in the anteroposterior direction and semi-rounded in the occipital region. In posterior view the parietals are quite vertical with a curvature starting in the upper third. The lateral cranial walls are, therefore, parallel to the superior parietal bones which are short, flat and slightly convergent. Above the root of the left zygomatic process there is a postglenoid foramen, indicating the presence of a petrosquamous sinus (PSS). The small temporal bone (squama temporalis) shows a linear upper profile (plesiomorphy) with a maximum height from porion of 37.8mm on the right side and 35.2mm on the left, and a length of ~55.7mm on the right and ~58.5mm on the left. The squamous suture descends vertically, at a right angle, to the parietomastoid suture. The zygomatic process extends posteriorly over the porus acusticus externus, in a horizontal suprameatal and supramastoid ridge in line with the torus occipitalis. The mastoid and supramastoid ridges, especially on the right side, appear to be separated by a slight supramastoid groove. The porus is oval (width 7.1mm; height 8.9mm and transverse width 10.0mm), oriented almost vertically and is separated from the mastoid process. The tympanomastoid fissure, which separates the tympanic plate from the mastoid process, is absent on the right but may be present on the left. On this side, a slight line of separation between the plate tympanic and the mastoid process is in fact visible, interrupted by a small post-mortem damage. This trait is considered an autapomorphy of Asian H. erectus⁶¹. The anterior mastoid tubercle is absent as in early European proto-Neanderthals (i.e. Atapuerca-SH and Krapina⁶²) and the anteriorly closed digastric sulcus is present (plesiomorphy). The juxtamastoid eminence is incomplete and eroded but we believe both the juxtamastoid and occipitomastoid crests are absent. The mastoid process is small with underdeveloped apophysis and incomplete apex. In the basicranium the mandibular fossa, bilaterally preserved, is deep. It has a squamotympanic fissure (STF) [Extended Data, Fig.2] that runs into the roof of the fossa itself and a coronally oriented tympanic plate⁶³. In C1 skull the STF fissure is posterior to the apex of the fossa. The posterior wall of the TMJ (Temporomandibular Joint) is formed exclusively by the tympanic plate which ends with a thickened and wrinkled crest (process supratubalis?) extending, only on the left, up to the meatus (Extended Data, Fig.2, Supplementary, Fig.S6). The presence of an entoglenoid tubercle is uncertain (Extended Data, Fig.2) [the postglenoid-entoglenoid length is 22.0 mm]. Contrary to C1 skull, the styloid process is not fused to the skull base (autapomorphy for Asian H. erectus⁶¹) and the vaginal process is not present (autapomorphy H. erectus³⁶). The postglenoid process is absent (apomorphy⁶³). The styloid foramen is not in line with the digastric sulcus. The carotid foramen, visible only on the right, is posterior to the STF fissure. It shows a thickening of the opening margin, of ~2.1mm, and a narrowing of the canal (hole opening diameter 6 mm) which could indicate progressive carotid narrowing (Extended Data, Fig. 2a). On the left side, unfortunately, only a small portion of the foramen ovale is preserved which does not allow us to evaluate whether it was double (accessory foramen) or bifurcated as in some Indonesian specimens, including Sambungmacan 4⁶⁴. The sigmoid sinuses are vertical, and it is possible that near the left sigmoid sinus there is a distinct sulcus (Supplementary, Fig. S7) which could represent the residue of an atypical drainage pattern of the intracranial sinuses (arborizing sigmoid sinus) found, and described by Schwartz³⁴, in Sangiran2 and Sangiran4 (autapomorphy). The occipital bone shows ectocranial thickening on the superior nuchal line (underdeveloped nuchal torus). The transverse torus occipitalis expands laterally in the direction of the asterion, most noticeably on the right side. Between the superior and supreme nuchal line there is a small and smooth suprainiac fossa, circular in shape. This localization determines a depression of the external occipital protuberance which interrupts the slight torus occipital resulting in a double arch morphology. The inion is located well above the endinion. A probable tuberculum linearum is located near a very poorly developed external occipital crest. The occipitoparietal area is flat and the occipital plane, although presenting a rounded protuberance (swelling) delimited inferiorly by the superior nuchal line, remains in line with the convexity of the nuchal plane. The posterior projection of the squama occipitalis (chignon) present in C1 skull and more generally in classical Neanderthals is absent in this specimen. The nuchal plane area is incomplete. Sutural synostosis shows interdigitations on the outer table and an incomplete obliteration on the inner table. Individual C5 is a young adult female presenting with mild internal frontal hyperostosis.

Circeo 6 (C6)

Mandible. Fossil find found inside the cave, “Antro del laghetto” area (Fig. 1.3, Extended Data, Figs. 3A, a, a1).

C6 is an anterior interforaminal portion (synphysis). The mandibular symphysis is characterized by the absence of the mental trigone. It shows a slight hint of the chin eminence (mentum) with incurvatio mandibulae in lateral view which may be accentuated by the presence of bone atrophy due to intravitam tooth loss. C6 has on the right side (the left side is incomplete) a single oval mandibular foramen, horizontal and parallel to the masticatory plane and located under M₁ (P₄). It measures 3.3 x 2.4 mm and is located ~15.3 mm from the alveolar crest (bone loss due to tooth loss) and ~15.5 mm from the basal crest. The table S8 shows the comparative values. The digastric fossa is directed downwards and posteriorly. In C6, severely atrophied alveolar areas show residual alveolar ridge morphology consistent with tooth loss before death (Supplementary, Table S8a). The alveolar ridge of the central incisors does not present horizontal atrophy and the bone level is normal. The presence of a thin fracture line involving only the external alveolar bone is noted in correspondence with the right central and lateral incisors.

Circeo 8 (C8)

Occipital bone (squama occipitalis). Fossil find found inside the cave, “Antro del laghetto” area, composed of a portion plus a fragment (Fig. 1.3, Supplementary, Fig. S8).

The ectocranial surface morphology of the fossil is well preserved except for some areas of erosion. The endocranial surface is covered with concretions. The occipital plane is convex and low and flattens into the vertical suprainiac fossa. The nuchal plane is incomplete. An occipital bun is absent. The "nuchal torus", heavily eroded, is an ectocranial thickening located above the superior nuchal line. The inion is located immediately above the endinion. The suprainiac fossa, located on the superior margin of this thickening, contributes to the determination of its "bilateral arch" morphology. The torus has no margins but an upper and lower thinning. The transverse torus is thickened medially, lacks significant lateral development. The external occipital protuberance is absent. The suprainiac fossa is an elliptical depression above the inion which do not extend higher on the occipital plane. Its surface is pocked. In Neanderthals, the suprainiac fossa is more pocked in children⁶⁵. The interdigitations of the lambdoid suture, without traces of synostosis, and the pocked surface of the suprainiac fossa indicate that this occipital bone could belong to a young individual,therefore not compatible with C4. In Tables 2 and 3 (Supplementary, Tables S3, S4) metric and comparative values are reported.

Circeo 9 (C9)

Palatine process of maxilla. Fossil find found inside the cave, “Antro del laghetto” area (Fig. 1.3, Supplementary, Fig.S9).

Although the finding shows a severe erosive aggression, the presence of a progressive alveolar ridge atrophy due to tooth absence is evident. The sinuses sit above the upper teeth. If the upper teeth are missing, the sinuses can drop down and invade the space meant to be occupied by the teeth roots. The maxilla in the palatal view (palatine) presents slight traces of palatine torus along the margins of the medial palatine suture. There is an asymmetry of thickness between the right and left sides of the palate. Residual dental alveoli on the right while the left anterior alveolar ridge shows bone remodeling. The nasal view shows a large piriform opening and the presence of a probable lateral crest (Supplementary, Fig. S9C) as documented for C1 and SH skull 5⁶⁶. The base of the nasal septum appears moderately curved to the left. The dimensions (mm) are: Nasion-Prosthion Height (n-pr, NPH) ⁓15.3, total height 26.2; Maxillo-Alveolar Length (pr-alv, MAL) ⁓ 39.5; Maxillo-Alveolar Breadth (ecm-ecm, MAB) ⁓ 52.6 and 39.8 (end-end); Nasal Breadth (al-al, NLB) ⁓ 25.

Dental sample

Circeo 10a and b (C10a-C10b). Fossil find found in the area outside the cave (Fig. 1.3)

Permanent maxillary molars and alveolar part (Supplementary, Fig. S10 and Table S9).

Second and third right upper molars (M²-M³), contiguous and compatible. Both are probably from the same adult individual. A small portion of alveolar bone is present (M² in alveolar bone). The estimated age for tooth wear is adult. Characteristics of the tooth: M² right: presence of grade 3.5 metaconus and hypocone, absence of 5th cusp, Carabelli tubercle and parastyle, presence of grade 2 enamel extension and three roots; M3 right: absence of 5th cusp.

Circeo 13 (C13). Fossil find found inside the cave, “Antro del laghetto” area (Fig.1.3)

Permanent upper canine (Supplementary, Fig.S10 and Table S9)

Right upper canine (C¹). Estimated age for tooth wear: young adult. Characteristics of tooth: probable absence of shovel absence of tubercle in the cingle, extension of enamel, presence of root. Slight apical hypercementosis.

Circeo 14 (C14). Fossil find found inside the cave, “Antro del laghetto” area (Fig.1.3)

Permanent upper second premolar tooth (Supplementary, Fig. S10 and Table S9)

Right upper second premolar (P⁴). Estimated age for tooth wear: young adult; characteristics of tooth: presence of two lingual cusps, enamel extension. Presence of taurodontism and hypercementosis. On the buccal surface of the crown there is an archaic character from the Middle and Upper Pleistocene consisting of a buccal vertical groove (Extended Data, Fig. 4).

Circeo 11 (C11). Fossil find found inside the cave, “Antro del laghetto” area (Fig.1.3)

Permanent lower molar (Supplementary, Fig.S11 and Table S9)

Probably a right lower third molar (M₃). It could also be a lower right third molar (M₃) because the contact facet on the distal side is missing. Estimated age for tooth wear: young adult. Probable presence of an anterior fovea, sulci pattern = +, presence of 4 cusps, absence of 6th and 7th. Presence of taurodontism and hypercementosis.

Circeo 12 (C12). Fossil find found inside the cave, “Antro del laghetto” area (Fig.1.3)

Permanent lower molar, (Supplementary, Fig. S11 and Table S9)

Left lower third molar (₃M). Estimated age for tooth wear: adult. Characteristics of tooth: sulci model = (+), presence of n. 4 cusps, presence of middle trigonid ridge (grade 1A) and fovea anterior, absence of protostilis, 5th, 6th, 7th cusps and extension of enamel, presence of two roots.

Circeo 15 (C15). Fossil find found inside the cave, “Antro del laghetto” area (Fig.1.3)

Crown and root part of a permanent tooth, (Supplementary, Fig. S12 and Table S9)

Part of the crown and root of a small permanent upper right first molar (M¹) (Supplementary, Table S9). The crown, although incomplete, shows a mesiodistally compressed morphology and the roots, which are also incomplete, are small and strongly splayed. Distal contact facet is present. Severe wear. Dental characteristics: Grade (1) enamel extension.

Post-cranium

Circeo 7 (C7)

Right femur (diaphysis). Fossil find found inside the cave, “Antro del laghetto area” (Fig. 1.3, Supplementary, Fig. S13)

C7 is without both epiphyses, probably due to endogenous action of a hyena. The maximum length of the preserved diaphysis is 310 mm. Strongly curved femoral shaft. It is compressed in the subtrochanteric part and moderately compressed in the middle of the diaphysis (Table 4). The linea aspera is continuous and undivided. Its degree of expression is modest but in its proximal portion it is more prominent probably due to a pilasterconsisting of a slight underlying bony crest (Supplementary, Fig. S14). Distally the line deviates in a medial direction, becomes smoother, less marked and tends to fade. The areas of muscle insertion appear modest in both the proximal and distal thirds. In the Table 4 the comparative values medio-lateral and antero-posterior, of the proximal, distal and mid-diaphyseal diameters are reported. C7 falls within the ranges of variation of H. erectus, Neanderthals, and modern humans.

Circeo 16 a (C16a)

Incomplete left coxal bone. Fossil find found inside the cave, “Antro del laghetto” area (Fig. 1.3, Supplementary, Fig. S15)

The partial iliac bone preserves the incomplete iliac wing, a small portion of the auricular surface, a remnant of the tubercle of the iliac crest, a small, preserved margin of the anterior superior iliac spine and the anterior inferior iliac spine. The latter is accentuated by an evident supra-acetabular sulcus (and by post-mortem damage) which extends between the acetabulospinal buttress and the acetabular rim. Finally, a portion of the acetabulum is preserved (fossa), with exposure of the spongy bone on the acetabular rim, and a portion of the greater sciatic notch. The portion of the greater sciatic notch present has a height of ~12mm and a width of 30.6mm. The composite morphology of the arch, formed by the sciatic notch and the auricular surface, is consistent with the female morphology. The ischium and pubis are completely missing. In the lateral view, the presence of a single ventral iliac buttress acetabulocrystal (vertical) is noted with a height of ~79mm [in Krapina 207 the height is 90.9mm⁶⁷]and 28.9mm distant from the anterior superior iliac spine. The thickness of the buttress varies from a maximum of 23.9mm near the acetabular fossa to a minimum of 15.8mm near the tubercle of the iliac crest. Its central thickness is 19.5mm. In Krapina 207 the thickness is 12.4mm⁶⁷. In medial view there is a well-defined arcuate line and a thick iliosciatic buttress (24.4mm). The height from the acetabular fossa to the iliac crest is ~115.4mm.

Circeo 16 b (C16b)

Incomplete right coxal bone. Fossil find found inside the cave, “Antro del laghetto” area (Fig. 1.3, Supplementary, Fig. S16)

The partial iliac bone preserves the incomplete iliac wing, a portion of the auricular surface, a small remnant of the iliac crest (tubercle iliac crest?), a small preserved margin of the anterior inferior iliac spine, the latter accentuated by an evident supra-acetabular sulcus which extends between the acetabulospinal buttress and the acetabular rim, a portion of the acetabular fossa with exposure of the spongy bone on the acetabular rim and finally a portion of the greater sciatic notch, preserved for a height of ~22.3mm and a width of 39.5mm. The composite morphology of the arch, formed by the sciatic notch and the auricular surface, is consistent with the female morphology. The ischium and pubis are completely missing. In the lateral view, the presence of a single ventral iliac acetabulospinal buttress with a height of ~42.6mm is noted (concretions are present). The thickness of the buttress varies from a maximum of 25.0mm near the acetabular fossa to a minimum of 17.0mm. Its central thickness is 21.0mm. There is a thick iliosciatic buttress (23.1mm). The height from the acetabular fossa to the iliac crest is ~106mm. Given the small value of this height, a link with C5 cannot be excluded.

The human fossil remains of Circeo (I and II discovery) show a series of apomorphic and plesiomorphic characteristics known in Asian H. erectus (s.s and s.l.), in the proto-Neanderthal and classical European Neanderthal and in modern human. The frontal bones of C4 and C5 both present a similar morphology, with a marked frontal torus and a notable thickness, that are totally divergent from C1 skull. The supraorbital torus of C4 and C5 resembles that of Asian and European H. erectus (ZKD 12 and 5 and Lazaret 24) as well as that of the European proto-Neanderthal (Biache-Saint-Vaast2-BSV2 and Petralona). The supraorbital torus is wide and continuous and the profile in norma verticalis does not present a gabellar depression. The supratoral sulcus is defined and continuous in C5 but discontinuous in C4, where it is interrupted by a convexity in correspondence with the glabella as in the Indonesian specimen Ngadong5³⁶. In this case, this covexity could be due to or probably accentuated by the morphology of the frontal sinus. Contrary to C4, in C5 calvarium, BSV2⁶⁸, Lazaret24 and C1 skull the supraratoral sulcus is pronounced. The frontal sinuses of C4 are asymmetric, well developed and with multiple chambers. The minimum frontal diameter (M9) of C4 and C5 calvarium is higher than that of BSV2 (Supplementary, Table S2) and Neanderthal values (Table 5) however, very similar to the value of C1 skull, slightly lower than Amud1 and in line with Ngadong 11 and WLH 50 (Australian) [Supplementary, Table S2]. In the ratio between the M43 and M9 values (Supplementary, Table S2), Circeo 4 and 5 shows a postorbital narrowing and a widening towards the parietal walls, lower than that of classical Neanderthals. The frontal sagittal profile differs from that of classic Neanderthals such as C1, La Chapelle-aux-Saints, La Ferrassie1 etc. which, unlike C4 and C5, present an anterior position of the glabella with respect to the nasion. In norma lateralis the upper profile of the C5 calvarium is high and rounded as in the Indonesian fossils (Sangiran, Sambungmacan, Ngadong) showing a convex frontal contour (absent in C4) which increases in the protrusion of the bregmatic eminence. The distance from the glabella to bregma (frontal chord and arc gl-br), taken in the mid-sagittal plane, is greater in C4 (~114.8mm and ~120mm) than in C5 (107mm and 112mm) but both fall within the Javanese range (105-120mm). In the post-obelic region of C5 there is a slight inflection followed by an occipital protuberance which does not correspond to the classic bun. The occipital profile described by Schwartz³⁴ for the specimens Sangiran 2 (S2) and Sambungmacan1 (SM1): "rounded between the anteriorly inclined occipital and nuchal planes which gives the short occipital supero-inferiorly a blunt V-shaped profile »” shows similarities with C5 especially in comparison with SM1. In C5, Ngawi 1 and Sangiran3 (S3), the morphology of the torus occipital is similar to the Ngandong specimens, but less prominent³⁴. As mentioned above, the C5 calvarium, the focus of this analysis, displays apomorphic and plesiomorphic characteristics known in H. erectus s.s proto-Neanderthals, classical European Neanderthals, and Sapiens.

The frontal bone of C5 shows, contrary to C1 skull and presumably also to C4, a frontal "keel" (Extended Data, Fig.1, Supplementary, Fig. S5) with a morphology described by Schwartz et al.³⁴ as unique in Trinil 2 (autapomorphy) and present in Sangiran specimens. The frontal Keel of C5, like Trinil 2, is defined by a pair of anteroposteriorly long and mediolaterally wide depressions in the frontal squama^{60, 34} (Extended Data, Fig.1, Supplementary, Fig. S5). C5, like the Indonesian specimens, also has a bregmatic eminence that does not extend bilaterally into the coronal keels or posteriorly into a sagittal keel, although it does have a pair of small depressions located posterior to the bregma^60,34. Contrary to the Ngandong specimens⁶⁹ the bregmatic eminence of C5 is not separated from the frontal keel. In all proto-Neanderthal samples from Atapuerca SH, a mid-sagittal keel on the squama frontalis is described⁶⁶, although the authors believe that it does not exactly reflect the morphology and autapomorphic characteristics of the Asian Homo erectus holotype Trinil 2 a data that, according to the authors, would confirm the absence of this trait in Neanderthals⁶⁶. Contextually the supraorbital torus of C5 would seem more similar to that of Lazaret 24⁷⁰and BSV2^{69, 68}. The latter was defined as type III in the Cunningham classification system⁶⁸ and considered similar to that of Sima de los Huesos 5, Bilzingsleben and the Neanderthals⁶⁸. The sagittal profile of the C5 calvarium shows a similar contour to S2, SM1 and Ngandong. The curve of the parieto-temporal bone in the coronal plane is more vertical than the rounded profile of classic Neanderthals such as C1, La Chapelle-aux-Saints, Ferrassie 1 and is very similar to the “tent” morphology (due to the presence of the bregmatic eminence, Extended Data, Fig. 1C) of the Indonesian sample SM 4 and very similar to that of the West Asian (Israel) specimen Manot1 (55 Ka,⁷¹). In C5, as in Manot1 and modern humans, the maximum cranial width is positioned high, and the lateral walls are vertical and almost parallel⁷¹. The biasterionic breadth of C5 is larger than that of Manot 1, which is extremely small, but is similar to that of Shanidar 1, Sale (Erectus, Morocco), Xuchang (XUC2) and within of the Java range (Supplementary, Table S2). The convexity (bunning) of the occipital bone of C5 and C8 is not as marked as in C1 (although in C8 it is more defined than in C5), Manot 1, the Chapelle-aux-Saints and as in the Middle Pleistocene fossils upper of Africa (Jebel Irhoud in Morocco) and Europe (Neanderthal). According to Hershkovitz et al.⁷¹ the presence of a bunning is not necessarily related to interbreeding between Neanderthals and modern human as it is not present in Middle Eastern Neanderthals (e.g., Amud 1). The authors therefore consider it reasonable to suppose that this morphological trait originated in modern Near Eastern humans, or even earlier, in some African populations such as Aduma (~79–105 ka), who later migrated to the Levant. Furthermore, we observed in C5 the presence of a slight parietal flattening that extends into the lambdoid region. In Manot 1 as in BSV1, some characteristics considered typical of the classical Neanderthal but sometimes also present in other fossils are described. These characteristics refer to a lambdoid flattening of the parietal bones associated with the occipital conformation (double arched-shape profile parietal and occipital concavities). This medial change in the posterior parietal curve has been identified as a prelambdic depression indicating the presence of an occipital bun. An appearance that would correspond to a classic Neanderthal trait described for C1, La Chapelle-aux-Saints, Spy 2 and La Ferrassie 1. C5, as mentioned above, presents a slight parietal flattening that extends into the lambdoid region but does not present an occipital conformation referable to the classic Neanderthal defined by the presence of an occipital chignon. We therefore believe that it is not the double-arch parietal and occipital profile described for Manot 1 and BSV1 but of a characteristic of the Ngadong specimens, described by Zhang (Doctoral dissertation⁷²) corresponding to a depression in the posterior parietal region that ends at the lambda. Also, regarding the temporal bone, the presence/absence of a mosaic of very specific characters (autapomorphic and symplesiomorphic) relating to H. erectus s.s., H erectus s.l. (late Indonesian) and Neanderthal have been detected. H. erectus is usually described as having a “well-developed or marked” mastoid and supramastoid crests, which are separated from each other by a supramastoid groove or in some cases fused (Doctoral dissertation⁷²). These crests, separated by a slight supramastoid sulcus, would appear to be present in C5 in a sort of generalized hypertrophy of the temporal (without the angular torus). The tympanomastoid fissure, which separates the tympanic plate from the mastoid process, is absent on the right but may be present on the left. On this side, a slight line of separation between the plate tympanic and the mastoid process is in fact visible, interrupted by a small post-mortem damage. This trait is considered an autapomorphy of Asian H. erectus⁶¹. The mandibular fossa of C5 (Extended Data, Fig.2), bilaterally preserved (Supplementary, Fig.S6), presents in a very similar morphology to the Ngandong specimens^63,73, with a coronally oriented tympanic plate (plesiomorphy⁶³) and an STF fissure that runs in the roof of the fossa itself with the posterior wall of the TMJ formed exclusively by the tympanic plate. In C1 the tympanic plate is oriented coronally, but the STF fissure is posterior to the apex of the fossa. The tympanic plate is thought to be oriented coronally in H. erectus and sagittally in modern humans. The opinion regarding the Neanderthal condition is controversial: For Weidenreich⁷⁴ and Stringer^61,75, the tympanic bone is positioned sagittally in Neanderthals while for other authors^{76, 77} it is positioned coronally. C5, it does not present the stylomastoid process, i.e. it is not fused to the skull base and does not present the postglenoid process as in the Ngandong specimen. In Asian H. erectus the postglenoid process is much reduced (apomorphy⁶³), the styloid process is absent (apomorphy⁶³). A well-developed postglenoid process is a feature of the proto-Neanderthal SH sample, is present in BSV2⁶⁸ and in classical Neanderthals (including C1 skull). The European Middle Pleistocene fossils, Castel di Guido and Ceprano, also show a well-developed postglenoid process⁶³. The styloid process is fused to the petrous bone in all SH specimens and in Neanderthals as C1 (except some specimens from Krapina and Shanidar 1⁶³). In Middle Pleistocene Asian fossils, both conditions are present (Narmada, Dali, and Xujiyao show the styloid process although Hexian and Yunxian 2 lack it⁶³). In C5 the digastric sulcus and the stylomastoid foramen do not are aligned. In BSV2 and in classical Neanderthals the digastric sulcus, the base of the styloid process and the styloid foramen do not are aligned, because the styloid process is located more medially compared to the digastric sulcus⁶⁸.

In C5 the vaginal process of the petrous bone is absent but has a thickened and wrinkled crest [Extended Data, Fig.2 (process supratubalis?)] extended, only on the left, up to the meatus as in Sts19⁷⁸(Fig.18A⁷⁸), in Sangiran (2, 4 and 17), Ngandong and Sambungmacan 4⁶⁴. As in Sangiran (4 and 17) and Ngandong (6, 7, 10, 11 and 12) the carotid foramen of C5 is posterior to the STF fissure.

In similar form to the Ngandong and SM3 specimens, as described by Zhang (Doctoral dissertation⁷²) the mandibular fossa of C5 is deep. A short lateral part of the posterior margin of the mandibular fossa is open, due to the absence of the postglenoid process. The tympanic plate, mediolaterally short and coronally oriented, is higher than the articular eminence; its anterior surface is convex. The auditory meatus is oval and oriented almost vertically; it is separated from the mastoid process.

In C5 the mastoid process is small as a conservation of the primitive condition of H. erectus^{74, 75, 36}, the anterior mastoid tubercle is absent, and the digastric sulcus is closed anteriorly (plesiomorphies). The presence of an anterior mastoid tubercle is a trait considered to be autapomorphic in Neanderthals^{79, 80, 81, 69, 61, 82, 83} although Frayer⁸⁴believes to have found several Neanderthal specimens without the anterior mastoid tubercle (Gibraltar 1, La Quina 27, Saccopastore 1 and 11 adult specimens of Krapina), it is also absent in the proto-Neanderthal BSV2 sample⁶⁸. The anteriorly closed digatric sulcus is a very particular morphology consistently found in Neanderthals although it may be present in several specimens from the Lower Zhoukoudian Cave⁶⁶. This tract is described as consisting of an elevation of the floor of the digastric sulcus in its anterior part, a sort of saddle-like elevation that almost obliterates the sulcus^63,⁶⁶. A similar character was also described by Guipert et al.⁶⁸, in the proto-Neandertal BSV2 sample.

C5 calvarium, unlike C1 and similarly to the Ngandong specimen, has a squama temporalis with a flat upper edge. The apomorphic state of the squama temporalis with a convex upper border is present in Middle Pleistocene samples from Africa (Bodo, Salé), Europe (SH sample, Petralona and Steinheim) and Asia (Dali), Neanderthal and modern human^63,66. Furthermore, in C5 it is possible that traces of an atypical intracranial sinus drainage pattern (arborizing sigmoid sinus) found, and described by Schwartz³⁴, in S2 and S4, consisting of a distinct groove that diverges from the sinus sigmoid. In C5, a distinct but small sulcus is visible near the left sigmoid sinus (Supplementary, Fig. S7) which could represent the residue of the same system or a variant but in any case, a drainage model of the sinus Erectus considered by the author to be potentially apomorphic in as referable the Trinil 2 hypodigma (and therefore to the Erectus)³⁴.

In C5 the inion is located well above the endinion, in contrast to Manot 1, where the inion is located below the endinion. In C8 the endinion region is strongly concretioned, nevertheless it is possible to determine that the inion is located immediately above the endinion. The separation between inion and endinion is an important trait from a taxonomic point of view as the spatial relationship of the endinion located well below the inion is considered a classic anatomical characteristic of Homo erectus⁸⁵. Nonetheless, this condition has occasionally also been found in Neanderthals and in this case considered a primitive character. The external squama occipitalis of C5 has a small, shallow, rounded suprainiac fossa located between the supreme and superior nuchal lines in a central localization. This localization determines a depression of the external occipital protuberance which interrupts the slight and straight torus occipital resulting in a double arch morphology reminiscent of that of some Indonesian specimens (Ngandong 7 and 12). Schwartz and Tattersall^86,72 describe the occipital torus of all Ngandong specimens as having a variable prominence, lateral extension to the asterion, and two curved nuchal lines that join at the midline to produce a strong external occipital protuberance. Therefore, on each side, the lower edge of the torus appears bow shaped. According to the authors⁸⁶, this explains why the occipital torus of the Ngandong specimens has been described as double-arched. In C5, Ngawi1 and S3, the morphology of the occipital torus is similar to the Ngandong specimens, but less prominent^{86, 72}. On the contrary, in C8 the occipital plane is convex and low and flattens into the suprainiac fossa. There is no occipital bun present. The heavily eroded "torus nuchal" is an ectocranial thickening located above the upper nuchal line. The supraniac fossa, located at the upper edge of this thickening, contributes to defining the "bilateral arch" morphology. This morphology, curved bilaterally and poorly defined laterally, is typical of Neanderthals⁶⁵. The torus has no margins, but tapers above and below. The transverse torus is thickened medially and not defined laterally. The external occipital protuberance is absent. What has been described defines the "classical" morphology of the Neanderthal posterior neurocranium⁷¹. Another relevant and characterizing aspect C4 and C5 emerges from the presence of a significantly marked cranial bone thickness compared to that of classic Neanderthal skull such as C1 and to that of the European diachronic specimens (Supplementary, Table S7), which it turns out to be very close to thickness of Proto-neanderthals (thickness at lambda), H. erectus, early archaic Humans and H. sapiens Middle Eastern (Tables 2,6 and Supplementary, Tables S4-S7). C4 and C5 are therefore characterized by a significant cranial thickness, slightly greater in C4, made up of an expanded diploic bone and thin laminae (inner and outer tables). In both samples the thickness of the supraorbital torus decreases in the lateral direction while the thickness values of the frontal bone exceed those of the parietal bone (Supplemmentary, Tables S6, S7). The high values of the parietal eminence of C5 (Table 6, Supplemetary, Table S6) are lower than the Australian sample (WLH 50), are close to those of the Asian and Indonesian sample (Sangiran, ZKD, Ngandong, Hexian and Xujiayao 9) and in general they diverge from the Middle-Superior Pleistocene values (Table 6). The thicknesses of C8 are higher than the Neanderthal average (except for Spy 1) and close to Proto-Neanderthals, Indonesian Asian samples, and Arcaic H. sapiens (Table 2, Supplementary, Table S4).

The fossil specimen C6, represented by a mandibular symphysis, has peculiar morphological features, such as the absence of mental trigone, a slight hint of chin eminence (mentum) with incurvatio mandibulae in lateral view, and the morphology and localization of the foramen mandibular in a horizontal position parallel to the masticatory plane. The mandibles of Circeo II (C2) and Circeo III (C3) also lack features suggestive of the presence of a true bony chin (Extended Data, Fig.3). In C2, the outlines of the symphysis are difficult to discern, there is no incurvatio mandibulae, and no evidence of a mental trigone. The lateral marginal tubercles, which are barely perceptible, are at levels C-P3, as in the primitive state (e.g., Dmanisi), and the mental pits and central keel are only indicated. C3 and C6 have the same features as C2, except for a slight suggestion of incurvatio mandibulae, which in C6 may be due to the presence of bone atrophy caused by intra-vitam tooth loss. C6 has a smaller bicanine width than C3 and is very similar to C2. As reported by Vialet et al.⁸⁷, the absence of a bony chin is predicted for the middle Pleistocene, and the mental trigone appeared early in the evolution of the genus Homo. According to the authors reports, the mandibles of OH 7 and OH 3 from the lower Pleistocene have both the mentum osseum and the mental trigone. The latter is present in KNM-ER 730, Sangiran 9, and Sangiran 22, while a small mental protrusion is described in the mandibles of Dmanisi and in specimen ATE9-1 from the Sima del Elefante site (Sierra de Atapuerca). Finally, in the Middle Pleistocene, it is described in Tighenif 1 and 2 and in the Zhoukoudian mandible. It is interesting to note that the symphysis of the Circeo mandibles has a configuration very similar to that described for the Montmaurin-LN mandibles, i.e., "primitive, devoid of any characteristic that defines the bony chin derived from H. sapiens like most of the mandibles from the Middle European Pleistocene, with the exception of two of the specimens from the Atapuerca-SH site⁸⁷”. In mandible C6, the fossa digastrica is directed downward and posteriorly, as in C2 and C3. A pattern documented in Neanderthals that appears to diverge from the downward-facing primitive model and the generally posterior-facing modern model⁸⁷. The C6 mandible has only one horizontal oval mandibular foramen (Neanderthal-like) on the right side (the left side is incomplete) below the M₁(P₄) localization (Supplementary, Table S8). It measures 3.3 x 2.4 mm and is located approximately 15.3 mm from the alveolar ridge (bone loss due to tooth loss) and approximately 15.5 mm from the basal ridge. The C2 mandible, like the Montmaurin-LN mandible, has two foramina on the right (not very pronounced) and left sides of the body (Supplemetary, Table S8). The main foramina are located below the M₁ position. The smaller foramina are located below the main foramina on both sides. The two foramina appear to be connected and are separated only by a bone bridge, which has a longitudinal groove on the left side. The C3 mandible has two foramina on both sides, with the second foramen on the left side not clearly visible. The large foramina are located below the localization of M₁-P₄. The smaller foramina, such as in C2, are located below the main foramina on both sides and appear to be connected and separated only by a bony bridge (Supplementary, Table S8). The presence of multiple foramina is not uncommon in the early and middle Pleistocene and is most commonly found in Pleistocene Asian mandibles⁸⁷. Regarding the position of the foramina, a primitive state seems to correspond to a more advanced position (P₃-P₄), while in contrast, the foramen below M₁-P₄ and M₁ is common in Neanderthal and most Central European Pleistocene hominins⁸⁷.

In C6, the severely atrophied alveolar areas show residual alveolar ridge morphology consistent with tooth loss before death (Supplementary, Table S8a). After tooth loss, a series of alveolar bone changes (new bone formation and volumetric resorption) occur, resulting in a change in the dimensions and contours of the alveolar ridge⁸⁸. Data from one study (meta-analysis) conducted on a modern sample showed an average reduction in buccolingual alveolar ridge thickness of 3.87 mm and vertical mid-buccal resorption of 1.67 mm after unassisted alveolar bone healing⁸⁹. The multifactorial etiopathogenesis of tooth loss does not allow us to determine a specific cause, but for C6, gradual tooth loss due to pyogenic factors (exogenous or endogenous) is excluded, at least as far as the central incisors are concerned. In fact, the alveolar ridge of the central incisors does not show horizontal atrophy and the bone level is normal. Bacterially induced alveolar bone resorption usually proceeds by a flattening of the alveolar crest (horizontal bone loss) and an enlargement of the bone socket in which the tooth is located (vertical bone loss⁹⁰). We therefore believe it is probable that the loss of the incisors of the C6 individual can be more easily traced back to a traumatic event which could be confirmed by the presence of a short fracture line in correspondence with the external alveolar bone. Circeo 9 (C9), a palatine process of the maxilla, due to its poor state of preservation, heavily eroded and incomplete, did not allow for an in-depth comparative morphometric analysis. The presence of osteolytic alterations associated with tooth loss (with various degrees of atrophy), and the presence of a thickness asymmetry that emerged between the two portions of the palatine bone, require a targeted tomographic analysis which is currently outside the scope of this study. From an exclusively morphological point of view, we cannot completely exclude a hypothetical relationship with C6, as well as with C2 or C3, a hypothesis that will require future investigations and insights. The only comparative data that emerged concerns the pyriform opening with the presence of the probable residue of a lateral crest (Supplementary, Fig. S9C) documented in SH skull 5⁶⁶ but above all in C1 skull. An aspect that could prove interesting from a phyletic point of view.

The dental sample consisting of a total of seven teeth, of which only two pertain to a single individual (upper M² and M³, C10a-b), confirms the presence of a mosaic of characters found in late Erectus, Neanderthals and Sapiens, as documented for the entire Circeo human sample. From a non-metric morphological point of view, in fact, dental traits emerge that are strongly indicative of a Neanderthal morph, such as the presence on the lower molars of an anterior fovea associated with the middle trigonid crest (C12), and the presence of an archaic character from the middle and upper Pleistocene, i.e. a buccal vertical groove on P⁴(C14) [Extended Data, Fig.4], a rare character present in H. luzonensis and 15,000-year-old H. sapiens (Dushan1)^35,4.

The metric results (Supplementary, Table S9) confirm the phenetic relationships that emerged from the morphological analyses: The entire dental sample shows values well within the Neanderthal variability, including C2 and C3, except for C15 (M¹) and C14 (P⁴) which are at outside the variability of all hominins except H. luzonensis (M¹ and P⁴ HlCCH6 and P⁴/P³ HlCCH8). It is interesting to note that the crown of C15, although incomplete, is small in size and compressed mesiodistally while the residue of the root portion shows small and divergent roots (Supplementary, Fig. S12), a morphology shared with the dental specimen from Southeast Asia (Luzon and Dushan)^35,4. The general characterization of this dental sample associated with a simplification of the occlusal basin, as found in H. sapiens, confirms the presence of a mosaic morphology as found for the entire human sample from Circeo.

Regarding the postcranial skeleton, some interesting data emerge from the analysis of the coxal bones. C16 a and b are two left and right iliac portions with female morphology. Due to the presence of some variations relating to thickness, size and morphology, we believe that they do not belong to the same individual. In medial view C16a and b show the presence of a single iliac buttress and of the supra-acetabular sulcus, while the interspinous notch is absent (Supplementary, Figs.S15, S16). The supra-acetabular sulcus is a fossa (fossa supra-acetabularis) between the iliac buttress and the acetabular rim in a similar way to SK50, SK3155, to the first representatives of the genus Homo (KNM ER 3228, KNM WT 15000) to African fossil samples from the lower and middle Pleistocene (OH 28 and Broken Hill E 719) and finally to the European Neandertals^91,67. Most Pleistocene hominins are thought to have a supra-acetabular sulcus/fossa, including Arago XLIV, OH 28, Skhul IV, and most Neandertal hip bones, including Krapina, Amud 1, La Chapelle-aux Saints, La Ferrassie I, Hortus XLV, Neandertal 1 and Sima Pelvis 1⁹¹. Rarely, some Australopithecus (e.g., Sts 14, TM-1605, SK 50) and some modern humans show a supra-acetabular fossa^{91, 67}. The comparison between C16a and C16b highlights differences in the morphology of the iliac buttress and in the thickness values. C16a presents a single ventral acetabulocrystal buttress (a primitive character) while C16b presents a single acetabulospinal buttress as in Sts14 (Supplementary, Figs.S15, S16). Indeed, A. Africanus Sts14 displays a single ventral iliac buttress (acetabulospinal buttress) near the anterior margin⁶⁷as C16b. Regarding the genus Homo, two buttresses are found in specimens attributed to Homo ergaster (KNM ER 3228, OH 28), Homo heidelbergensis (Arago 44, sample Sima de los Huesos) and Homo neanderthalensis (Neandertal 1, Kebara 2, Amud 1, La Ferrassie 1, La Chapelle-aux-Saints 1, and Krapina⁶⁷). Among modern human fossils, Qafzeh 9 shows a single ventral acetabulospinal buttress near the anterior edge, while Skhul 4 shows the acetabulocrystal buttress. Homo sapiens has when present, a single acetabulocrystal buttress⁶⁷. The only comparable metric values concern the height and thickness of the acetabulocrystal buttress. C16a has a height of the iliac buttress (79.0mm) lower than Krapina 207 (90.9mm) while the thickness is greater (19.5mm in C16a and 12.4mm in Krapina 207). C16 a and b differ in thickness and the presence of an analogy between C16b, and Omo 1 emerges⁹¹. The iliac thickness measured at the greater sciatic notch is: 23.3mm in C16b, 22.7mm in Omo 1 and 20.7mm in C16a; the ilium, at the base of the auricular surface, has a thickness of 27.3mm in C16b, 26.4mm in Omo1 and 25.7mm in C16a. Finally, there is a thickening of the bone above the acetabulum which corresponds to the very base of the Anterior Inferior Iliac Spine (AIIS) in both C16b and Omo1.

The iliosciatic buttress, consisting of the surface that extends from the arcuate line to the deepest portion of the greater ischial notch, shows in C16a and b a robust pillar-like morphology as in Krapina 207⁹¹. Among fossils, iliosciatic morphology is variable: narrow and pillar-shaped (SK 3155, SK 50, Arago 44, AT-Pelvis 1, AT-800), broad and flat (AL 288-1), and intermediate (Sts 14, KNMER 3228, OH 28, AT3807-3809, AT3300 and AT1004)⁹¹. The characters detected on C16a and b, which in summary consist of a probable oblique auricular surface (C16b), a laterally flared iliac blade (C16b) and robust acetabulocrystal, acetabulosacral and iliosciatic buttresses, could also be among the traits characterizing H. erectus⁹². Finally, we believe that C16b compared to C16a presents a complex morphology characterized not only by the presence of a notable thickness but above all by a reduced height from the center of the acetabular cavity to the iliac crest of only 106 mm (~) which brings it closer to H. floresiensis Indonesian (105 mm⁹³).

The C7 right femur, lacking the distal and proximal epiphysis, has curved diaphysis, linea aspera with a medio-distal deviation in a medial direction, probable pilaster (Supplementary, Figs. S13, S14) thought to be absent in Neanderthals⁹⁴, an evident sub-trochanteric plathymer and a medium cortical thickness. These characteristics fall within the ranges of morphological variation of H. erectus, Neanderthals, and modern humans. The periosteal contour is subcircular. In the comparative analysis (Table 4) the values of the proximal, distal and mid-diaphyseal dimensions of C7 do not highlight the presence of significant variability. In the analysis of single values⁹⁵ the mid-diaphyseal dimensions (M6, M7 and distal) of C7 do not fall within any range of variation of the samples compared, with the exception of Ferrassie1 [Early Pleistocene, Middle Pleistocene, Neandertals, MPMH (Middle Paleolithic Modern humans) and EUP/MUP (Early/Mid Upper Paleolithic Modern humans)]⁹⁵. While a divergence clearly emerges in the relationship between the mid-diaphyseal diameters (AP-ML) which highlights the absence, in C7, of the classic circular morphology documented in almost the entire fossil sample. C7 is characterized by antero-posterior diameter values (M6) lower than the transverse diameter (M7) and therefore inverted compared to the values of all the comparison samples which present a more circular morphology (Table 4).

In C7 there is therefore a variation compared to the late Pleistocene samples but documented in some early and middle Pleistocene samples (KNM-ER 737 and 803; Ehringsdorf 5, Kresna11, OH28, Zhoukoudian 1,4-6, Ferrassie 1,2, Quina5, Tabun1,3)⁹⁵. The shape of the femoral section shows some reduction in proportions from anteroposterior to mediolateral compared to the Early Pleistocene specimen. C7 presents an anteroposterior convexity, a characteristic observed on the femoral shafts of Neanderthals. Based on the overall morphometric results we hypothesize a phyletic relationship with Neanderthals and modern humans by placing C7 within the range of variation of European Neanderthals.

The Circeo sample shows autapomorphic features independent of Homo erectus and synapomorphic features shared with proto-Neanderthals, Neanderthals, late Erectus of Southeast Asia, and Sapiens which suggest a phyletic link between these taxa. The morphological qualitative data find a positive response in the quantitative metric results (both in linear measurements and in thicknesses) which place the entire Circeo sample in a mixed but geographically well-defined context between Europe and Asia as was predictable but with a new and unexpected extension towards Southeast Asia.

The first consideration to be made concerns the two reference chronologies: the older one, which refers to the area outside the cave (currently under study) and dated to around 120 ka, and the internal one, the so-called Antro del laghetto, dated at approximately 65-66ka²⁸. These two chronologies indicate that the site was visited at different times (MIS5.5, MIS5d and MIS4) by multiple human lineages, including Neanderthals. The hominin remains almost all come from the internal area called Antro del laghetto, except for two teeth (C10a, b) and a mandible (C3) found in an external fault, but with the same stratigraphy as the Antro del laghetto. It is important to remember that the first finds (C1 skull and one of the two mandibles, C2) were found inside the Guattari Cave and therefore fall within the chronology of the Antro del laghetto. Considering all the finds from the first (I) and second (II) discovery as a whole, a substantial morphological variability is noted. In general lines, the C1 skull shows all the classic morphological characteristics of the latest contemporary Neanderthals such as Feldhofer, La Ferrassie, La Chapelle-aux-Saints, La Quina. In contrast, the C5 calvarium shows a complex mosaic of primitive and derived features that make it difficult to classify it within the group of so-called classical Neanderthals. Despite the smaller volumetric dimensions of C5, the thicknesses of the frontal bone and parietal bone are notable, as in C4 and do not fall within the Neanderthal variability. The mandibles confirm what was underlined for the cranial findings. The three mandibles C2, C3 and C6 show apomorphic characteristics, such as the presence of a slight incurvatio mandibulae in lateral view (C3 and C6) and the localization of the mental foramen, which is in the direction of the symphysis between M1 and P4. Typically, Neandertal characters emerge from the dental sample, such as the presence of the middle trigonid crest, rare characters such as the buccal vertical groove and a general tendency towards a modern simplification of occlusal morphology.

Going into detail, the morphometric analysis of the sample (I and II discovery) indicates the presence of a mosaic of characteristics shared with proto-Neanderthals, classical Neanderthals, H. erectus s.s. and s.l., and archaic Middle Eastern (Israel) H. sapiens.

In C4 and C5 a close similarity of the supratoral region is observed with Biache-Saint-Vaast 2. Nonetheless C5 differs from the European fossils of the Middle Pleistocene (SH, Steinheim, Petralona, Castel di Guido, Ehringsdorf), which share numerous traits including the derived feature of a relatively flat articular eminence, and from the SH specimen characterized by a strongly protruding postglenoid process, which appears to be shared, at least, by Castel di Guido, Petralona, and Steinheim⁶³. All Neanderthal specimens, including C1 and C5, share the plesiomorphic tract in the mastoid region consisting of an anteriorly obliterated digastric groove. The European Middle Pleistocene fossils from Ehringsdorf H, La Chaise (Suard) and Biache-Saint-Vaast 2 also share this feature. "Classic" European Neandertals display as C1 an autapomorphy (anterior mastoid tubercle), which is not present in C5 as in earlier Asian or European Neanderthal specimens ^62,63.

The morphological similarities of C5 with H. erectus s,s. they are essentially linked to the presence of a frontal keel, described in Trinil 2 holotype of Erectus, a trait that allows us to place this specimen in the lineage Erectus³⁴. The supratoral region of C4 and C5 highlights an affinity with the European late Erectus (Lazaret 24) and more generally with H. erectus s.l. for some features found on the mandibular fossa. According to Martínez and Arsuaga⁶³, two derived features can be used to characterize the temporal bone of H. erectus: a strong reduction of the postglenoid process and the absence of the styloid process and both are documented in C5. Furthermore, the particular morphology of the temporomandibular joint of this specimen, very similar to that described in Indonesian samples (Javanese H. erectus p-deme), highlights the existence of a possible phenetic relationship also with the late Erectus of south-east Asia. This particular morphology is in fact considered a distinctive anatomical characteristic of the Ngandong specimen with which the human sample of Circeo share several other cranial morphometric characteristics. A further element confirming the existence of an affinity with the South-East Asian lineages is given by the singular presence, within the Circeo sample, of a rare dental tract (buccal vertical groove) from the Middle Pleistocene, found on find C14 (upper premolar) which has been documented in late H. erectus (H. luzonensis) and H. sapiens (Dushan 1). Therefore, H. luzonensis and Dushan 1 show in analogy with the Guattari cave dental specimen a mosaic of primitive and rare dental traits together with some characteristics of H. sapiens, such as a simplified occlusal surface^35,4. Traits of Middle Eastern archaic Sapiens (Israel) also emerge in the vertical parieto-temporal morphology of C5 very similar to Manot1⁷⁰ and from the coxal bones (C16a, b) characterized by a single iliac buttress as documented in the Skhul/Qafzeh group⁶⁷.

The human sample from Guattari Cave would therefore appear to be characterized by a high variability which would suggest not only the coexistence of multiple morph/taxa within the same site but above all the existence of complex phyletic relationships which would involve synchronic, diachronic and geographically distant Eurasian lineages. In the reconstruction of the dispersions and evolutionary trajectories of Homo in Eurasia in the final Pleistocene, the identification of a Javanese morph in the context of Circeo represents an important element of evaluation for the reconstruction of new evolutionary scenarios in the first half of the final Pleistocene. The first consideration we can make concerns the close chrono-morphological similarity that emerged between the Circeo sample and the last Indonesian Erectus, including H. luzonensis, and which could modify the hypothesis regarding the extinction of H. erectus in south-east Asia. It is believed that the hominins of Southeast Asia, in the final stages of the Pleistocene, have lived in a sort of insular isolation until extinction ³⁸, but this may not be the case. The late discovery ⁴¹ of a Denisovan molar (TNH2-1) in the Tam Ngu Hao2 cave in Southeast Asia, which presents Neanderthal characters (middle trigonid crest), indicates the possibility that a phyletic link exists between Neanderthals and meridional Denisova of Southeast Asia and therefore between Europe and Southeast Asia. In confirmation, genetic studies on ancient and modern human mitochondrial DNA (mtDNA) have revealed the existence of important turnover of the Eurasian population in the late Pleistocene⁵². In the absence of molecular findings, searching for combined features in the human fossil record from Circeo may help define this as an alternative hypothesis on human movements in Eurasia:

Between 120 and 110Ka (after the final stage of the interglacial MIS 5.5) the late Erectus of south-east Asia may have come into contact, in continental Asia, with the Erectus-Neanderthal/Denisovia (Altai and meridional) and early Sapiens who circulated in the geographical area which extends from the Altai mountains to central-eastern Europe up to the extreme south-east Asia. The mixture of distinct characters, documented in the Circeo sample, would suggest that the migratory flows of the first half of the late Pleistocene in Eurasia also included South-East Asia. This hypothesis foresees the possibility that a first and older dispersal from Asia → Europe (Italy) and a second late and rapid dispersal from Europe → Asia → South-East Asia may have occurred (Fig. 2). The morphometric results on the human sample from Circeo highlight a high degree of individual variability and therefore the prospect of a possible crossing between multiple lineages. According to what emerged, the hypothesis of a process of hybridization and dispersal in a late phase of the Pleistocene (66-65Ka) could emerge. Therefore, the high variability found, and the presence of small individuals (C5 and C16b) could document the result of hybridization between archaic and modern humans. According to Martinón-torres et al. ⁴³ “Hybrid skeletons of extant primates tend to show an increase or decrease in size (heterosis and dysgenesis), and hybrid populations are characterized by high degrees of individual variability.”

The Circeo hominins and the hominins of south-eastern Asia share on the one hand similar time intervals but on the other enormous geographical distances, an incongruity that could be explained by placing the Circeo hominins in the second dispersal, proposed by Zanolli et al. ³⁷, by modern humans, which pushed from Europe into continental Asia and Southeast Asia during the late Pleistocene. Genetic data suggest that Denisovans interbred with modern humans, Neanderthals, and an unknown third archaic hominin lineage, perhaps a late surviving H. erectus, although its identity remains unclear^{7, 96}. Among the archaic or post-erectus hominins that could represent the Denisovans⁹⁷, the Xuchang skull⁹⁸ and the Maba skull have been reported and present a mosaic of features similar to H. erectus and of Neanderthal, the first, and some typical Neanderthal traits⁹⁹ and a morphology considered congruent with the genetic proximity of Denisovans and pre-Neanderthal populations^100,101, the second. Could the mosaic of H. erectus- and Neanderthal-like features found on the Circeo 5 calvarium make this specimen a further candidate to represent the Denisovans?

According to Kaifu³ the archaic Denisovans lived over a wide geographical and ecological range, from Siberia to tropical Asia and according to the author there is no doubt that the first settlers of Sahul were descendants of populations who migrated using the southern routes of the Himalayan mountains in the Late Pleistocene. Considering the existing controversy on the times and paths followed by populations pre-modern human and the vast geographical area taken into consideration, we believe that a European involvement within this turnover that involved the last Asian Erectus (Indonesian), could be plausible Denisovians (Altai and meridional), Neanderthals and archaic Middle Eastern Sapiens in multiple dispersals, in the final Pleistocene, to and from Southeast Asia, as demonstrated by mitochondrial DNA results⁵² and Denisovan admixture (southern) detected in extant Australo-Melanesian populations ³ .

The human sample from Circeo, based on the numerous characteristics highlighted and the combination of primitive and derived traits, could therefore be involved in the transition between H. erectus, Neanderthal e Sapiens. Morphometric analyses support this statement and above all indicate the existence of a close phyletic relationship between European and Asian fossils from the final Pleistocene and modern humans. The long-term presence of H. erectus and Neanderthals in Eurasia suggests that they were meta-populations, with a long and undoubtedly successful biological history, having survived multiple ice ages with climatic fluctuations and related climatic-environmental changes that represented an uphill battle for survival. The hominins who resided in Guattari cave between 120 and 60 ka probably represent the result of a biological mix between a first wave of migration towards the Italian peninsula and the native populations that populated the region. It was undoubtedly a dynamic meeting of different genetic flows, in which a unique territorial adaptation to a climatically and nutritionally advantageous area can be observed. The new population, belonging to a Neanderthal time horizon and found in the Guattari cave site, may have finally pushed, due to the rigid climatic-environmental conditions and through land bridges, towards new geographical horizons up to the extreme south-east Asia, joining to the second late dispersal that contributed to determining the genetic diversity of the first modern humans who spread across Eurasia during the late Pleistocene.

We thank Doctor Flavio Altamura for his contribution to the historical section.

Table 1

Circeo 5 (C5) calvaria morphology compared with lower, middle and upper Pleistocene specimens
Specimens	Styloid process fused to the basicranium	Specimens	Anterior mastoid tubercle	Specimens	Bridge of bone on the digastric groove
C5 (present study)	No	C5 (present study)	No	C5 (present study)	Yes
Circeo 1	Yes	Circeo 1	Yes	Circeo 1	Yes
ZKD 102	Yes	ZKD 101–102	No	ZKD 101–102	No
Qafzeh 9	Yes	Dolni Vestonice 3	No	Dolni Vestonice 3	No
Skhul 5	Yes	Predmostì 3	No	Predmostì 3	No
Dolni Vestonice 3	Yes	Predmosti 4	No	Skhul 5	No
Predmostì 3	Yes	Qafzeh 9	No	Qafzeh 6-7- 9	No
Predmosti 4	Yes	Skhul 5	No	Spy 1	Yes
Spy 1	Yes	Gibraltar 1	No	Gibraltar 1	Yes
Spy 2	Yes	Spy 1	Yes	Saccopastore 1	Yes
La Quina 5	Yes	Spy 2	Yes	Saccopastore 2	No
La Chapelle	Yes	Saccopastore 1	No	La Quina 5	No
La Ferrassie 1	Yes	La Quina 5	Yes	La Ferrassie 1	Yes
Le Moustier	Yes	La Chapelle	Yes	La Chapelle	Yes
Engis 2	No	La Ferrassie 1	Yes	Le Moustier	Yes
La Quina 18	Yes	Amud	Yes	Engis 2	Yes
Shanidar 1	No	Saccopastore 2	No	La Quina 18	Yes
Krapina sample	Yes	Shanidar 2	No	Tabun C1	Yes
Steinheim	Yes	Shanidar 5	No	Amud 1	Yes
Petralona	Yes	La Quina 18	Yes	Shanidar 1	No
SH sample	Yes	Krapina sample	No	Krapina sample	Yes
Laetoli 18	No	BroKen Hill	No	Steinheim	No
Omo 2	Yes	Ndutu	No	La Chaise Suard	Yes
Ndutu	Yes	Omo 2	No	Biache-Saint-Vaast	Yes
BroKen Hill	Yes	Laetoli 18	No	SH sample	No
Yunxian	No	SH sample	No	Laetoli 18	Yes
Xujiyao	Yes	H. erectus sample	No	Omo 2	No
Hexian	No	ER 3883	No	Ndutu	No
Dali	Yes	ER 3733	No	BroKen Hill	No
Narmada	Yes	OH 9	No	Ngandong 12	No
Ngandong sample	No			Skull XI	No
Sangiran 4	No			Skull III	Yes
ZKD sample	No			Sangiran sample	No
OH 9	Yes			OH 9	No
ER 3733	Yes			ER 3733	No
ER 3883	No			ER 3883	No
ER 3735	Yes

Comparison data taken from Ref. ⁶³

Table 2

Circeo 8 and Circeo 5 - Occipital bone thickness (measurements mm)
Specimen/Sample	Lambda	Inion	Asterion
Circeo 8 (present study)	10.5	Concretions	12.9
Circeo 5 (present study)	13.5	17	11
Circeo 1	-	11	-
Proto-Neanderthals mean ± s.d. (n)	10 (1)	-	9.5 (1)
Neanderthal (Early - Late) mean ± s.d. (n)	8.6 ± 1.36 (7)	-	8.9 ± 2 (14)
Neanderthal mean ± s.d. (n)	8.2 ± 1.2 (8)	10.67 ± 2.24 (9)	8.9 ± 2 (14)
late H. erectus (Indonesian) mean ± s.d. (n)	10.50 ± 3.91(5)	22.16 ± 2.83(5)	-
WLH 50	16.2 (1)	18 (1)	-
H. sapiens Arcaic (Israel) mean ± s.d. (n)	9.38 ± 1.80 (4)	-	-
Cro-Magnon 1	9 (1)	-	-
Mladeč 5	7.5 (1)	-	-
H. sapiens mean ± s.d. (n)	8.8 ± 1.7 (6)	-	-

Comparison data was taken from:

Ref. ¹⁰² Proto-Neanderthals and Neanderthal (Early - Late).

Ref. ^103,104 Neanderthal and H. sapiens.

Ref. ¹⁰⁵ late H. erectus.

Table 3

Circeo 8 and Circeo 5 - Occipital bone linear measurements (mm)
Specimen/Sample	Bi-asterionic breadth M12	Lambda-inion M31(1)	Lambda-asterion M30(3)	Inion-asterion
Circeo 8 (present study)	123.2	61.5	86.9	⁓73.2
Circeo 5 (present study)	118.5	59.8	86.3(r) 87.8(l)	71.1
Circeo 1	124	63,1	94,3	67.7
Proto-Neanderthals mean ± s.d. (n)	123.4 ± 11.6 (11)	-	-	-
Neanderthal mean ± s.d. (n)	115.02 ± 7.43 (14)	60.01 ± 3.17 (16)	86.83 ± 5.63 (11)	67.64 ± 4.32 (11)
H. erectus (Asia) mean ± s.d. (n)	122.63 ± 7.95 (8)	53.25 ± 4.10 (8)	-	-
Late H. erectus (Indonesia) mean ± s.d. (n)	125.11 ± 3.73 (10)	77.36 ± 14.29 (8)	59.13 ± 4.42 (8)	74.58 ± 4.35 (6)
H. sapiens mean ± s.d. (n)	112 ± 12.3 (4)	64 ± 2 (3)	-	-

Comparison data was taken from:

Ref. ¹⁰² Protoneanderthal

Ref. ^104,23 Neanderthal

Ref. ^36,105, H. erectus and late H. erectus

Ref. ⁷¹H. sapiens.

Table 4

**Circeo 7 (C7) femur diaphysis - Linear diaphyseal diameters** (measurements mm)
Specimen/Sample	Proximal		Midshaft		Distal
	A-P (M10)	M-L (M9)	A-P (M6)	M-L (M7)	A-P	M-L
C7 (present study)	27.2	36.5	27.8	31.5	28.5	32.4
Early Pleistocene	(5) 24.9 ± 3.3	(5) 34.1 ± 4.1	(6) 28.2 ± 4.7	(6) 30.5 ± 5.3	-	-
Middle Pleistocene	(11) 24.4 ± 2.8	(12) 33.7 ± 3.7	(19) 27.6 ± 3.8	(19) 28.6 ± 2.5	-	-
NTK-F-07-05*	-	-	-	-	(1) 38.05	(1) 44.85
H. erectus (Java)*	-	-	-	-	(1) 34.15	(1) 37.65
H. erectus (Tautavel)*	-	-	-	-	(1) 32.55	(1) 36.9
Neanderthals	(27) 26.8 ± 2,9	(27) 33.5 ± 2,8	(22) 29.3 ± 3.4	(22) 29.4 ± 2.3	(1) 40.7*	(1) 47.3*
MPMH	(9) 28.1 ± 2.1	(9) 33.1 ± 3.6	(12) 34.0 ± 5.0	(12) 27.4 ± 1.7	-	-
EUP/MUP	(62) 25.7 ± 3.3	(60) 34.5 ± 4.1	(56) 31.4 ± 4.8	(56) 27.1 ± 2.6	-	-

M–L, Medio-lateral and A–P, Antero-posterior diameter. Mean and Standard deviation (±), number (n)

Ref. ⁹⁵

*Central Narmada Valley (India) Ref. ¹⁰⁶

Table 5

Circeo 4 (C4) and Circeo 5 (C5) - Linear measurements (mm)
Specimen/Sample	Length Max Glabella-Opisthocranion g-op M1	Breadth Max Euryon-Euryon eu-eu M8	Frontal diameter Least frontal breadth ft-ft M9*	Frontal Breadth Max co-co M10	Bioccip breadth ast-ast M12	Porion-Bregma height M20
C4 (present study)	-	-	112	-	-	-
C5 (present study)	195	145	112	123	118,5	99
Circeo 1	204	155	109	127	124	111
ProtoNeanderthal mean ± s.d. (n)	195.25 ± 11.73 (5)	140 ± 27.76 (4)	108.20 ± 6.35 (4)	118.52 ± 5 (5)	120.72 ± 7.38 (5)	-
Neanderthal mean ± s.d. (n)	199.73 ± 10.34 (11)	150.29 ± 6.26 (11)	107.74 ± 6.06 (8)	127.50 ± 2.12 (2)	120.93 ± 3.90 (6)	109.67 ± 6.78 (9)
H. erectus (Asia) mean ± s.d. (n)	192.05 ± 7.58 (9)	142.14 ± 6.20 (6)	86.54 ± 4.51 (9)	106.83 ± 4.88 (6)	115.45 ± 9.82 (9)	93.81 ± 14.51 (7)
Late H. erectus (Indonesia) mean ± s.d. (n)	201.22 ± 11.84 (11)	147.94 ± 9.57 (9)	103.13 ± 3.80 (8)	119.07 ± 4.12 (9)	126.01 ± 3.93 (11)	106.38 ± 4.98 (8)
H. sapiens mean ± s.d. (n)	197.40 ± 5.27 (5)	144.10 ± 2.92 (5)	94.83 ± 14.58 (3)	102 (1)	115.67 ± 5.69 (3)	99 (1)

Comparison data was taken from:

Ref. ^{68, 66, 107, 87} Proto Neanderthal and Neanderthal.

Ref. ^{3, 36, 108,105} H. erectus and Late H. erectus.

Ref. ⁷¹ H. sapiens.

Table 6

**Circeo 4 and Circeo 5 - Cranial vault thickness** (measurements mm)
Specimen/Sample	Bregma	Parietal eminence
Circeo 4 (present study)	9.6	-
Circeo 5 (present study)	10.3	12
Pleistocene Middle and superior		(35) 8.66 ± 2.2 5.0–17
Neanderthal	(13) 6.7 ± 1.4	(30) 8.3 ± 2.2
H. erectus*	(25) 9.4 ± 2.0	(25) 9.7 ± 2.3
Early archaic Humans	(14) 9.0 ± 2.2	(15) 10.3 ± 2.4
Pleistocene modern Humans	(17) 7.4 ± 2.0	(27) 7.4 ± 2.5
Holocene modern Humans	(16) 6.5 ± 0.7	(17) 5.8 ± 1.4

Mean and Standard deviation (±), number (n).

Comparison data was taken from:

Ref.^{109, 7,1110}

*Samples Ngandong1, 5, 10 and 11 were added

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New horizons on the knowledge of the population during the Middle/Late Pleistocene. The human remains of
Guattari Cave (S. Felice Circeo, Lt, Italy)

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2. Materials and methods

3. Results

Discussion

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New horizons on the knowledge of the population during the Middle/Late Pleistocene. The human remains ofGuattari Cave (S. Felice Circeo, Lt, Italy)

Status:

Version 1

Abstract

Figures

1. Introduction

2. Materials and methods

3. Results

Discussion

Ref. 95

References

Additional Declarations

Supplementary Files

Status:

Version 1

New horizons on the knowledge of the population during the Middle/Late Pleistocene. The human remains of
Guattari Cave (S. Felice Circeo, Lt, Italy)

Ref. ⁹⁵