Solo man in question: Convergent views to split Indonesian Homo erectus in two categories

Abstract

Between the famous Man of Java and the new star of paleoanthropology id est the Man of Flores, embedded in the bank of the river Solo or in the shadow of the volcanoes of Sangiran, Homo erectus remains apart. Driven from evolved Homo erectus to archaic Homo sapiens, for a long time Solo man did not find a real place in taxonomy and in the scientific debate, whereas Neandertal is still famous for its cultural or biological struggle against the ancestors of modern humans. Are there two human evolutionary trends: one in Europe with its first inhabitants over 1.3 Ma that became Neandertals, and another one in Asia, where human fossils are assessed to be older than 1.5 Ma? In 1932, Oppenoorth described Homo (Javanthropus) soloensis from the skull series gathered from the deposits of the Solo River. Since that time, some authors followed the point of view that this series belong to archaic Homo sapiens, but most paleoanthropologists considered them as evolved Homo erectus. To take stock of the taxonomy of Indonesian Homo erectus, three independent approaches and the authors' research done using different techniques and methods were compared. Considering the studies separately undertaken on Homo erectus (Brain structure analyses, 3D morphometry study, cladistic analysis performed from a biometric and morphological database), two categories existed. As far as a chronological gap splits these two categories, this reappraisal of Homo erectus poses the question of the possible occurrence of two different species. This question is still debated among the authors, but the convergent point of view brings new light on the multi-regionalism hypothesis within Homo. This Asian point of view sheds light on the older European evidence of human inhabitants.

Global and local perspectives on cranial shape variation in Indonesian <i>Homo erectus</i>

“…He attributed this combined pattern to geographic and genetic isolation of these populations on Java. In contrast, analysis of vault shape via 3D landmarks demonstrated distinct neurocranial shape in the Sambungmacan/Ngawi, Ngandong, and Trinil/ Sangiran groups, and the differences among them were non-linear (Baab, 2010;Zeitoun et al, 2010). At least some of the differences between the early Indonesian and the Ngandong fossils appear to relate to the increased size of the latter Baab, 2016b).…”

“…It was demonstrated that Asian, along with numerous African and Georgian fossils assigned to H. erectus, were distinct from or displayed minimal overlap with other archaic Homo species on the basis of threedimensional (3D) neurocranial shape (Zeitoun et al, 2010;Baab, 2016b). There is substantial variation within this sample that spans three continents and more than a million years of evolutionary change.…”

“…More recent work that has focused on the cranial morphology of the Asian H. erectus fossil record includes evaluations of the metric and non-metric diversity of Asian or specifically the Indonesian fossil record Kaifu et al, 2008), cranial shape variation in the Asian fossils (Baab, 2010;Zeitoun et al, 2010), and analyses focused on the affinities of particular fossils (Delson et al, 2001;Widianto et al, 2001;Widianto and Zeitoun, 2003;Durband, 2006;Kaifu et al, 2006Kaifu et al, , 2015Indriati and Antón, 2010). It was demonstrated that Asian, along with numerous African and Georgian fossils assigned to H. erectus, were distinct from or displayed minimal overlap with other archaic Homo species on the basis of threedimensional (3D) neurocranial shape (Zeitoun et al, 2010;Baab, 2016b).…”

“…Some of this variation is attributable to diachronic change (Wolpoff et al, 1994;Antón, 2003;Kaifu et al, 2005Kaifu et al, , 2008, and to geography (perhaps related to genetic drift or local adaptation) Kidder and Durband, 2004;Durband, 2006;Baab, 2010), but is also influenced by cranial size (Santa Luca, 1980;Antón et al, 2007;Baab, 2008b;Kaifu et al, 2008). Some studies have found that the Zhoukoudian hominins are particularly distinct in their craniometric dimensions Kidder and Durband, 2004), while others have indicated that the Ngandong/Sambungmacan/Ngawi series of calvaria are at least as distinct (Baab, 2010;Zeitoun et al, 2010).…”

“…At least some of the differences between the early Indonesian and the Ngandong fossils appear to relate to the increased size of the latter Baab, 2016b). A small number of workers argue that the morphological distance between the Trinil/ Sangiran and later Indonesian fossils should perhaps be recognized at the species level (Schwartz and Tattersall, 2005;Zeitoun et al, 2010), with a further possible split between Sambungmacan/Ngawi and Ngandong (Tattersall and Schwartz, 2009), but with the recognition that these samples form a single clade. Methodological and sample details differed among these studies.…”