Giorgio Manzi

Encephalization and allometric trajectories in the genus Homo: Evidence from the Neandertal and modern lineages

The term “encephalization” is commonly used to describe an enlargement in brain size, considered as either absolute endocranial volumes or relative values in relation to body size. It is widely recognized that a considerable endocranial expansion occurred throughout the evolution of the genus Homo. This article aims to evaluate whether this phenomenon was the outcome of distinct evolutionary lineages, reaching similar brain expansions but through different trajectories. Endocranial morphology was studied in a sample of fossil hominines by multivariate approaches using both traditional metrics and geometric morphometrics. The analysis was focused on the transition from a generalized archaic pattern within the genus Homo to the modern morphology and compared with changes that occurred along the Neandertal lineage. The main result was the identification of two different evolutionary trajectories, in which a similar expansion in endocranial size has been reached by different changes in shape. Along the Neandertal lineage we observed maintenance of an “archaic” endocranial model, in which a large amount of variability is based on a single allometric trend. By contrast, when modern endocasts were compared with nonmodern ones, we found important differences apparently led by a parietal expansion. In this light, the origin of our species may have represented the opportunity to surpass the constraints imposed on encephalization by the ontogenetic pattern shared by nonmodern Homo representatives.

Dental evidence on the hominin dispersals during the Pleistocene

A common assumption in the evolutionary scenario of the first Eurasian hominin populations is that they all had an African origin. This assumption also seems to apply for the Early and Middle Pleistocene populations, whose presence in Europe has been largely explained by a discontinuous flow of African emigrant waves. Only recently, some voices have speculated about the possibility of Asia being a center of speciation. However, no hard evidence has been presented to support this hypothesis. We present evidence from the most complete and up-to-date analysis of the hominin permanent dentition from Africa and Eurasia. The results show important morphological differences between the hominins found in both continents during the Pleistocene, suggesting that their evolutionary courses were relatively independent. We propose that the genetic impact of Asia in the colonization of Europe during the Early and Middle Pleistocene was stronger than that of Africa.

A cranium for the earliest Europeans: Phylogenetic position of the hominid from Ceprano, Italy

The human fossil evidence unequivocally pertaining to the first inhabitants of Europe at present includes the sample from Atapuerca-TD6 (Spain) and the incomplete adult calvaria discovered near Ceprano, in Southern Latium (Italy). On the basis of regional correlations and a series of absolute dates, the age of the Ceprano hominid is estimated to range between 800 and 900 kilo-annum (ka). In addition, the association with archaic (Mode 1) Paleolithic findings from the same area is suggested. After the completed reconstruction of the calvaria, we present here a new study dealing with the general and more detailed aspects of the morphology displayed by Ceprano, in comparison to fossil samples ranging between Early and Middle Pleistocene. According to our results, cranial features indicate that Ceprano represents a unique morphological bridge between the clade Homo ergaster/erectus and later Middle Pleistocene specimens commonly referred to Homo heidelbergensis (and/or to Homo rhodesiensis), particularly those belonging to the African fossil record that ultimately relates to the origin of modern humans. In conclusion, given its geographical, chronological, and phylogenetic position, an attribution to the species Homo antecessor is considered, although the sample from Atapuerca-TD6 is not directly comparable to Ceprano. Alternatively, a new species—ancestral to later European and African hominines—should be named to accommodate such a unique fossil specimen.

Discontinuity of life conditions at the transition from the Roman imperial age to the early middle ages: Example from central Italy evaluated by pathological dento-alveolar lesions.

Teeth are highly informative in the study of past human populations. In particular, the occurrence of lesions in the masticatory apparatus relates diseases, diet, and living conditions. The dental pathology of three skeletal samples from the north‐central part of Latium (central Italy) is reported. Two of them belong to the Roman Imperial Age (1st–3rd century AD): the first (including 942 permanent teeth and 1,085 tooth sockets) represents the rural town of Lucus Feroniae and is mainly composed of slaves and/or war veterans, whereas the second (872 permanent teeth and 1,325 tooth sockets) comes from the Isola Sacra necropolis at Portus Romae and represents the “middle class” segment of an urban population. The medieval sample (912 teeth and 1,097 tooth sockets), dated to the 7th century AD, belongs to the Lombard necropolis of La Selvicciola. All of the samples were examined for caries, abscesses, antemortem tooth loss, calculus, alveolar resorption, attrition, and enamel hypoplasia; standard methods were used to identify, classify, and quantify these conditions. The results reveal different patterns of dental and alveolar lesions for the three populations, indicating a different combination of dietary factors and hygienic conditions in the Roman samples compared to the Lombard series. As evidenced by multivariate correspondece analysis, the Romans show afffinites between each other, whereas the Medieval sample appears associated with the incidence of caries and the pathological conditions related to them, thus indicating increase of these lesions and deterioration of the quality of life in the transition to the early Middle Ages. These data agree with the respective archeological characterizations of the necropolises and the hypothetical social composition of each population. Am. J. Hum. Biol. 11:327–341.

The new chronology of the Ceprano calvarium (Italy)

IntroductionThe fossil human calvarium known as Ceprano (Latium, Italy) iscommonly dated to 800e900 ka, on the basis of geological andstratigraphical inferences (Ascenzi et al., 1996, 2000). This chro-nology appeared somehow consistent with the “archaic”morphology of the calvarium and its peculiar combination offeatures, which gave rise to a controversial taxonomic identity(Ascenzietal.,1996,2000;Clarke,2000;Manzietal.,2001;Mallegniet al., 2003; Bruner and Manzi, 2005, 2007). A re-evaluation of thislate Early Pleistocene chronology has been advanced by Muttoniet al. (2009) on the basis of paleomagnetic data. This hypothesis istested here, based on the combined evaluation of the multidisci-plinary evidence collected during recent systematic excavations.The specimen was discovered on 13 March 1994 within a claylevel partly destroyed by bulldozers working for a new road ina locality known as Campogrande (Fig. 1), about 3 km SW ofCeprano and 100 km SE of Rome, in Central Italy (for review andreferences see Manzi, 2004). The sediment containing the cranialfragments yielded more than 50 fragments. However, the craniumremainedincompletebecauseneitherportionsof thefacenorteethwere retrieved.The geological history of the Campogrande area was initiallyreferred to two main stratigraphic complexes (Ascenzi et al., 1996,2000; Ascenzi and Segre, 1997a,b): 1) upper fluvio-colluvialdeposits, with variable occurrence of volcanoclastic products (lateEarly to Middle Pleistocene); 2) lower lacustrine deposits, withoutvolcanoclastic products (roughly predating 1.0 Ma). The layercontaining the human calvarium was considered to belong to thelower portion of the upper stratigraphic complex. Its chronologywas inferred as more ancient than the Acheulean site of FontanaRanuccio, near Anagni (458 5.7 ka; Segre and Ascenzi, 1984),possiblyolderthan700ka,adatecorrespondingtothebeginningofthe volcanic activity in the region (Fornaseri, 1985).Given the presence in the Ceprano basin of various LowerPaleolithic assemblages, the archaic features of the calvarium andits hypothetical chronological position were considered in associ-ation with Mode 1, or Oldowan, techno-complexes (Biddittu,1984;Ascenzietal.,1996,2000).Mode1Paleolithicintheareacomefromvarious localities, including Arce, Castro de’ Volsci, Fontana Liri(Biddittu, 1972, 1974), as well as from the Campogrande area itself(see SOM-1), whose assemblages are characterized by flint orlimestone pebble-tools (mostly choppers, chopping-tools andpercussion tools), by debitage with hammerstone flakes, and byrelatively frequent cores, with a low degree of exploitation, mostoften unifacial, and high frequencyof cortical striking platforms. Asfor Mode 2 or Acheulean assemblages, new recent data (excava-tions 2001e2006; see below) have made it possible to bettercharacterize the material from Campogrande. These materials arenot numerically rich, but they yield evidence of each production

The Stem Species of Our Species: A Place for the Archaic Human Cranium from Ceprano, Italy

One of the present challenges in the study of human evolution is to recognize the hominin taxon that was ancestral to Homo sapiens. Some researchers regard H. heidelbergensis as the stem species involved in the evolutionary divergence leading to the emergence of H. sapiens in Africa, and to the evolution of the Neandertals in Europe. Nevertheless, the diagnosis and hypodigm of H. heidelbergensis still remain to be clarified. Here we evaluate the morphology of the incomplete cranium (calvarium) known as Ceprano whose age has been recently revised to the mid of the Middle Pleistocene, so as to test whether this specimen may be included in H. heidelbergensis. The analyses were performed according to a phenetic routine including geometric morphometrics and the evaluation of diagnostic discrete traits. The results strongly support the uniqueness of H. heidelbergensis on a wide geographical horizon, including both Eurasia and Africa. In this framework, the Ceprano calvarium – with its peculiar combination of archaic and derived traits – may represent, better than other penecontemporaneous specimens, an appropriate ancestral stock of this species, preceding the appearance of regional autapomorphic features.

A human deciduous tooth and new 40Ar/39Ar dating results from the Middle Pleistocene archaeological site of Isernia La pineta, southern Italy

Isernia La Pineta (south-central Italy, Molise) is one of the most important archaeological localities of the Middle Pleistocene in Western Europe. It is an extensive open-air site with abundant lithic industry and faunal remains distributed across four stratified archaeosurfaces that have been found in two sectors of the excavation (3c, 3a, 3s10 in sect. I; 3a in sect. II). The prehistoric attendance was close to a wet environment, with a series of small waterfalls and lakes associated to calcareous tufa deposits. An isolated human deciduous incisor (labelled IS42) was discovered in 2014 within the archaeological level 3 coll (overlying layer 3a) that, according to new 40Ar/39Ar measurements, is dated to about 583–561 ka, i.e. to the end of marine isotope stage (MIS) 15. Thus, the tooth is currently the oldest human fossil specimen in Italy; it is an important addition to the scanty European fossil record of the Middle Pleistocene, being associated with a lithic assemblage of local raw materials (flint and limestone) characterized by the absence of handaxes and reduction strategies primarily aimed at the production of small/medium-sized flakes. The faunal assemblage is dominated by ungulates often bearing cut marks. Combining chronology with the archaeological evidence, Isernia La Pineta exhibits a delay in the appearance of handaxes with respect to other European Palaeolithic sites of the Middle Pleistocene. Interestingly, this observation matches the persistence of archaic morphological features shown by the human calvarium from the Middle Pleistocene site of Ceprano, not far from Isernia (south-central Italy, Latium). In this perspective, our analysis is aimed to evaluate morphological features occurring in IS42.

Fractal dimension of the middle meningeal vessels: variation and evolution in Homo erectus, Neanderthals, and modern humans.

The middle meningeal vascular network leaves its traces on the endocranial surface because of the tight relationship between neurocranial development and brain growth. Analysing the endocast of fossil specimens, it is therefore possible to describe the morphology of these structures, leading inferences on the cerebral physiology and metabolism in extinct human groups. In this paper, general features of the meningeal vascular traces are described for specimens included in the Homo erectus, Homo neanderthalensis, and Homo sapiens hypodigms. The complexity of the arterial network is quantified by its fractal dimension, calculated through the box-counting method. Modern humans show significant differences from the other two taxa because of the anterior vascular dominance and the larger fractal dimension. Neither the fractal dimension nor the anterior development are merely associated with cranial size increase. Considering the differences between Neanderthals and modern humans, these results may be interpreted in terms of phylogeny, cerebral functions, or cranial structural network.

Paleoneurology of an "early" Neandertal: endocranial size, shape, and features of Saccopastore 1.

The Saccopastore 1 cranium was found near Rome in 1929, and its most probable age is about 120 ka (OIS 5e). The Neandertal morphology of the specimen was recognized just after the discovery by the Italian anthropologist S. Sergi, and subsequently confirmed by several authors. The present paper provides a complete description and analysis of the endocranial shape and features of this specimen, considering anatomical traits, metrics, and landmark data. The main endocranial diameters and the vascular traces resemble the morphology displayed by Middle Pleistocene humans, although lacking some traits described in the European samples referred to as ante-Neandertals. Nevertheless, proportions and endocranial shape support a definite Neandertal morphology, mostly taking into account the lateral development of the frontal lobes and the shape of the parietal areas. Therefore, it may be hypothesized that the Neandertal neurocranial architecture was present since at least OIS 5, as already suggested on the basis of ectocranial morphology.

New footprints from Laetoli (Tanzania) provide evidence for marked body size variation in early hominins

Laetoli is a well-known palaeontological locality in northern Tanzania whose outstanding record includes the earliest hominin footprints in the world (3.66 million years old), discovered in 1978 at Site G and attributed to Australopithecus afarensis. Here, we report hominin tracks unearthed in the new Site S at Laetoli and referred to two bipedal individuals (S1 and S2) moving on the same palaeosurface and in the same direction as the three hominins documented at Site G. The stature estimates for S1 greatly exceed those previously reconstructed for Au. afarensis from both skeletal material and footprint data. In combination with a comparative reappraisal of the Site G footprints, the evidence collected here embodies very important additions to the Pliocene record of hominin behaviour and morphology. Our results are consistent with considerable body size variation and, probably, degree of sexual dimorphism within a single species of bipedal hominins as early as 3.66 million years ago. DOI: http://dx.doi.org/10.7554/eLife.19568.001