Stone artifacts and hominins in island Southeast Asia: new insights from Flores, eastern Indonesia

This study reexamines the current understanding of Pleistocene stone-artifact assemblages in island Southeast Asia. A differentiation has long been made between assemblages of large-sized "core tools" and assemblages of small-sized "flake tools." "Core tool" assemblages are often argued to be the handiwork of early hominin species such as Homo erectus, while small-sized "flake tool" assemblages have been attributed to Homo sapiens. We argue that this traditional Southeast Asian perspective on stone tools assumes that the artifacts recovered from a site reflect a complete technological sequence. Our analyses of Pleistocene-age artifact assemblages from Flores, Indonesia, demonstrate that large pebble-based cores and small flake-based cores are aspects of one reduction sequence. We propose that the Flores pattern applies across island Southeast Asia: large-sized "core tool" assemblages are in fact a missing element of the small-sized flake-based reduction sequences found in many Pleistocene caves and rock-shelters. We conclude by discussing the implications of this for associating stone-artifact assemblages with hominin species in island Southeast Asia.     

Continuities in stone flaking technology at Liang Bua, Flores, Indonesia

This study examines trends in stone tool reduction technology at Liang Bua, Flores, Indonesia, where excavations have revealed a stratified artifact sequence spanning 95 k.yr. The reduction sequence practiced throughout the Pleistocene was straightforward and unchanging. Large flakes were produced off-site and carried into the cave where they were reduced centripetally and bifacially by four techniques: freehand, burination, truncation, and bipolar. The locus of technological complexity at Liang Bua was not in knapping products, but in the way techniques were integrated. This reduction sequence persisted across the Pleistocene/Holocene boundary with a minor shift favoring unifacial flaking after 11 ka. Other stone-related changes occurred at the same time, including the first appearance of edge-glossed flakes, a change in raw material selection, and more frequent fire-induced damage to stone artifacts. Later in the Holocene, technological complexity was generated by “adding-on” rectangular-sectioned stone adzes to the reduction sequence. The Pleistocene pattern is directly associated with Homo floresiensis skeletal remains and the Holocene changes correlate with the appearance of Homo sapiens. The one reduction sequence continues across this hominin replacement.     

The Liang Bua faunal remains: a 95 k.yr. sequence from Flores, East Indonesia

Excavations at Liang Bua, a limestone cave on the island of Flores, East Indonesia, have yielded a well-dated archaeological and faunal sequence spanning the last 95 k.yr., major climatic fluctuations, and two human species - H. floresiensis from 95 to 17 k.yr.¹, and modern humans from 11 k.yr. to the present. The faunal assemblage comprises well-preserved mammal, bird, reptile and mollusc remains, including examples of island gigantism in small mammals and the dwarfing of large taxa. Together with evidence from Early-Middle Pleistocene sites in the Soa Basin, it confirms the long-term isolation, impoverishment, and phylogenetic continuity of the Flores faunal community. The accumulation of Stegodon and Komodo dragon remains at the site in the Pleistocene is attributed to Homo floresiensis, while predatory birds, including an extinct species of owl, were largely responsible for the accumulation of the small vertebrates. The disappearance from the sequence of the two large-bodied, endemic mammals, Stegodon florensis insularis and Homo floresiensis, was associated with a volcanic eruption at 17 ka and precedes the earliest evidence for modern humans, who initiated use of mollusc and shell working, and began to introduce a range of exotic animals to the island. Faunal introductions during the Holocene included the Sulawesi warty pig (Sus celebensis) at about 7 ka, followed by the Eurasian pig (Sus scrofa), Long-tailed macaque, Javanese porcupine, and Masked palm civet at about 4 ka, and cattle, deer, and horse - possibly by the Portuguese within historic times. The Holocene sequence at the site also documents local faunal extinctions - a result of accelerating human population growth, habitat loss, and over-exploitation.     

Vegetation and soil seed bank of successional stages in tropical lowland deciduous forest

Abstract. We studied vegetation structure and soil seed bank composition in different successional stages of secondary lowland tropical deciduous forest in Yucatán, Mexico. The series of study sites includes: slashed (S), slashed-and-burned (SB), and regenerating for 1, 6, 10, 15, 30, 40 and 100 yr. Species richness (S = 42 - 65), evenness (E = 0.32 - 0.38), and diversity (H' = 1.2 - 1.6) do not vary much as the forest grows older. 20 species of shrubs and trees were present in at least six of the seven regrowth years studied; 10 of these account for more than 50% of the total density values per regrowth year. These species dominate the vegetation due to their capacity to withstand repeated fire and felling. One third of the individuals sampled had regenerated from coppiced shoots. Species composition little resembles that in earlier accounts. The area is now largely covered by young regrowth stages (1 - 20 yr). Species constituting the original woody structure of the mature forest are rare or absent due to the lack of seed sources and failure of dispersal (which is due to limited dispersal capacities), lack of dispersal agents, or long distances. Herbs were the most important life form in the soil seed banks; only one tree species was found. The number of viable seeds varied between sampled areas: 70/m² in the 40 yr-old, to 1 815/m² in the slashed-and-burned (SB). The vegetation of S- and SB-areas was the same, but the number of viable seeds germinating in SB was twice the number in S; the number of species in the seed bank is the same for both areas. We speculate that fire modifies species dominance early in succession, allowing seeds of some species to germinate in great numbers.     

Preface: research at Liang Bua, Flores, Indonesia

Excavations at Liang Bua, Flores, Indonesia, have yielded evidence for an endemic human species, Homo floresiensis, a population that occupied the cave between ∼95-17 ka. This discovery has major implications for early hominin evolution and dispersal in Africa and Asia, attracting worldwide interest. This preface describes the rationale for the excavations in historical, geographical, and wider research contexts, as well as the methods used. It also introduces the other papers on aspects of Liang Bua research that feature in this edition of the Journal of Human Evolution.     

Triassic Conifers as the basis for stratigraphical correlation

Floras with abundant Conifers have been recentlydiscovered in Siberia and China. They are correlated with the floras of the Voltzia sandstones of Western Europe.     

The fellowship of the hobbit: the fauna surrounding Homo floresiensis

The Late Pleistocene Flores fauna shows a pattern observed on many other islands. It is neither aberrant nor exclusive, but the result of non‐random selective forces acting upon an impoverished and disharmonic insular fauna. By comparing the Flores vertebrate fauna with other fossil insular biotas, it is apparent that the evolution of Homo floresiensis is part of a general pattern affecting all the inhabitants of Pleistocene Flores. Vertebrate evolution on Flores appears to have been characterized by phylogenetic continuity, low species richness and a disharmonic fauna. All three aspects stem from the isolated position of the island and have resulted in the distinct morphological characteristics of the Flores fauna. Evidence reviewed herein shows that features exhibited by H. floresiensis, such as small stature, a small brain, relatively long arms, robust lower limbs and long feet, are not unique, but are shared by other insular taxa. Therefore, the evolution of H. floresiensis can be explained by existing models of insular evolution and followed evolutionary pathways similar to those of the other terrestrial vertebrates inhabiting Pleistocene Flores.     

Geochronology of cave deposits at Liang Bua and of adjacent river terraces in the Wae Racang valley, western Flores, Indonesia: a synthesis of age estimates for the type locality of Homo floresiensis

A robust timeframe for the extant cave deposits at Liang Bua, and for the river terraces in the adjoining Wae Racang valley, is essential to constrain the period of existence and time of extinction of Homo floresiensis and other biota that have been excavated at this hominin type locality. Reliable age control is also required for the variety of artifacts excavated from these deposits, and to assist in environmental reconstructions for this river valley and for the region more broadly. In this paper, we summarize the available geochronological information for Liang Bua and its immediate environs, obtained using seven numerical-age methods: radiocarbon, thermoluminescence, optically- and infrared-stimulated luminescence (collectively known as optical dating), uranium-series, electron spin resonance, and coupled electron spin resonance/uranium-series. We synthesize the large number of numerical age determinations reported previously and present additional age estimates germane to questions of hominin evolution and extinction.     

The ecological impact of oceanic island colonization – a palaeoecological perspective from the Azores

Aim In many cases, human colonization drastically modified the ecosystems of remote oceanic islands before scientists arrived to document the changes. Palaeoecological records before and after human colonization provide insights into the original ecosystems and an assessment of subsequent human impact. We used pollen analysis to compare the impact of 15th century colonization of the Azores with that of natural disturbances such as volcanic eruptions and climate changes. Location Azores archipelago, Atlantic Ocean. Methods Sediment records from three highland sites in the Azores (on the islands of Pico and Flores) were dated radiometrically and analysed palynologically. Pollen taxa were classified as native, endemic or introduced based on comparison with flora lists. Data were statistically zoned and temporal trends identified using detrended correspondence analysis. Results Human colonization of the Azores resulted in rapid, widespread, persistent vegetation changes on a scale unprecedented in the last 2700 years, detectable through the decline of dominant trees, the spread of grasses and fire‐tolerant species, the introduction of exotic plants, evidence for grazing and fire, and changes to soils and moisture availability. During the same period, volcanic eruptions appear to have had more localized impacts on the vegetation, lasting 500–1000 years and favouring endemic taxa. The effect of late Holocene climatic changes on the highland vegetation of the Azores seems to have been minor. Palaeoecological data indicate that at least two plant species went extinct on Pico after human colonization and that some plants regarded as introduced were almost certainly part of the original flora of the islands. Despite a consistent signal of human impact, compositional differences between Juniperus brevifolia communities on Pico and Flores remained after colonization. Main conclusions Human colonization had a greater impact on the pristine vegetation of Pico and Flores than climatic changes and volcanic activity during recent millennia. The similarity between post‐colonization changes on the Azores and other oceanic islands suggests a consistent pattern and scale to historical‐era human impact on otherwise pristine ecosystems. These characteristics could be used to further elaborate biogeographical theory and direct conservation efforts towards species that appear most susceptible to human activity.     

The early lithic productions of Island Southeast Asia: Traditions or convergences?

Island Southeast Asia has been the subject of intense prehistoric investigations since the seminal work of Eugene Dubois in the late XIX^th century. This has resulted in several discoveries of a very diverse type of lithic productions of oftentimes debated age. Recent and old excavations have now secured the production of stone artefacts as early as 1 million years on Flores Island, 800,000 years on Java Island, 700,000 on Luzon Island and at least 118,000 years on Sulawesi Island. Along with these findings, several surface collections which most certainly date back to the Lower Palaeolithic are known, and adds to the diversity of the lithic productions. In this paper, we report what is at stake regarding our current knowledge over the early lithic productions of Island Southeast Asia, without giving more importance to one type of artefact over another. After describing the findings from each islands taken one by one, we compare the similarities and dissimilarities between these sometimes isolated and sometimes connected geographic entities. It appears that each of these islands might have had its own evolutionary trend with its own rhythm.