Katsuhiro Sano

New geological and palaeontological age constraint for the gorilla–human lineage split

The palaeobiological record of 12 million to 7 million years ago (Ma) is crucial to the elucidation of African ape and human origins, but few fossil assemblages of this period have been reported from sub-Saharan Africa. Since the 1970s, the Chorora Formation, Ethiopia, has been widely considered to contain ~10.5 million year (Myr) old mammalian fossils. More recently, Chororapithecus abyssinicus, a probable primitive member of the gorilla clade, was discovered from the formation. Here we report new field observations and geochemical, magnetostratigraphic and radioisotopic results that securely place the Chorora Formation sediments to between ~9 and ~7 Ma. The C. abyssinicus fossils are ~8.0 Myr old, forming a revised age constraint of the human–gorilla split. Other Chorora fossils range in age from ~8.5 to 7 Ma and comprise the first sub-Saharan mammalian assemblage that spans this period. These fossils suggest indigenous African evolution of multiple mammalian lineages/groups between 10 and 7 Ma, including a possible ancestral-descendent relationship between the ~9.8 Myr old Nakalipithecus nakayamai and C. abyssinicus. The new chronology and fossils suggest that faunal provinciality between eastern Africa and Eurasia had intensified by ~9 Ma, with decreased faunal interchange thereafter. The Chorora evidence supports the hypothesis of in situ African evolution of the Gorilla–Pan–human clade, and is concordant with the deeper divergence estimates of humans and great apes based on lower mutation rates of ~0.5 × 10−9 per site per year (refs 13, 14, 15).

Advanced maritime adaptation in the western Pacific coastal region extends back to 35,000-30,000 years before present.

Significance Moving into oceanic islands after c. 50,000 years ago was a remarkable step forward in the history of worldwide expansion of modern humans. However, the developmental process of Pleistocene maritime technology remains unclear. So far, the only secure sources of information for such discussions were the Indonesian Archipelago and northern New Guinea as steppingstones from the Asian continent to Australia. This article reports a successful maritime adaptation that extended from ∼35,000 to 13,000 years ago on a small island environment in the southern Japanese Archipelago. The new evidence demonstrates a geographically wider distribution of early maritime technology that extended north to the midlatitude areas along the western Pacific coast. Maritime adaptation was one of the essential factors that enabled modern humans to disperse all over the world. However, geographic distribution of early maritime technology during the Late Pleistocene remains unclear. At this time, the Indonesian Archipelago and eastern New Guinea stand as the sole, well-recognized area for secure Pleistocene evidence of repeated ocean crossings and advanced fishing technology. The incomplete archeological records also make it difficult to know whether modern humans could sustain their life on a resource-poor, small oceanic island for extended periods with Paleolithic technology. We here report evidence from a limestone cave site on Okinawa Island, Japan, of successive occupation that extends back to 35,000−30,000 y ago. Well-stratified strata at the Sakitari Cave site yielded a rich assemblage of seashell artifacts, including formally shaped tools, beads, and the world’s oldest fishhooks. These are accompanied by seasonally exploited food residue. The persistent occupation on this relatively small, geographically isolated island, as well as the appearance of Paleolithic sites on nearby islands by 30,000 y ago, suggest wider distribution of successful maritime adaptations than previously recognized, spanning the lower to midlatitude areas in the western Pacific coastal region.

Multidisciplinary Approaches to the Study of Stone Age Weaponry

Archaeologists have long sought a reliable means to identify whether certain pointed stone artifacts represent weapon armatures, and more specifically, whether specific types of pointed artifacts are associated with specific weapon technologies. These attempts have generally relied on ethnographic data; morphological, and more recently, morphometric, criteria; experimentation; use wear analyses; residue analyses; and combinations thereof. This paper is concerned with the reliability of established methods of identification of the stone arming tips of ancient weaponry, and in particular established means of differentiating weapon delivery technologies. The author presents a critical review of major attempts to isolate criteria intended to identify such artifacts and technologies; identifies deficiencies in the methodologies and criteria employed to date; and concludes that due to underlying subjective methods and a lack of comprehensive experimentation, current methods for identifying weapon armatures and delivery technologies lack sufficient scientific rigor.

Experiments in Fracture Patterns and Impact Velocity with Replica Hunting Weapons from Japan

Recent anthropological and archaeological studies in western Eurasia indicate that long-range projectile hunting was innovated by modern humans, and that complex projectile technology, such as using spearthrowers or bows (Shea and Sisk 2010), was an important component of behavioral modernity. The morphometric analysis of stone tips, including tip cross-sectional area (TCSA) and tip cross-sectional perimeter (TCSP), may facilitate suggestions for an optimum delivery method of stone tips as hunting weaponry. However, the suggested method does not always coincide with the true functions of the stone tips. Thus, this study developed a projectile experiment project to confirm additional indicators for identifying the delivery methods of prehistoric hunting armatures and to detect the emergence of spearthrower darts and bows and arrows in East Asia. Furthermore, macroscopic and microscopic analyses of the experimental specimens reveal a correlation between both the formation patterns of impact fractures as well as microscopic linear impact traces (MLIT) and impact velocities. This paper presents results of the projectile experiments, which provide indices to examine spearthrower darts and arrowheads in archaeological assemblages.

Mobility and Lithic Economy in the Terminal Pleistocene of Central Honshu

During the Terminal Pleistocene in central Honshu, which coincided temporally with the emergence of pottery, lithic raw material reduction sequences ceased to be rational and economical, instead becoming expedient and wasteful. Furthermore, hunter-gatherers had stopped importing lithic raw materials over long distances, and attempts made previously to attain a maximum number of usable edges on artifacts upon one nodule had ceased. Their reduction sequences might have no longer required a sparing strategy, since they now used abundant local raw materials, probably due to reduced mobility. It is suggested that the emergence of pottery allowed them to exploit more diverse plant sources and enabled them to survive within smaller territories, while the lithic reduction strategies changed as they adapted to use of available lithic raw materials.

Ecological Niche and Least-Cost Path Analyses to Estimate Optimal Migration Routes of Initial Upper Palaeolithic Populations to Eurasia

This paper presents a computer-based method to estimate optimal migration routes of early human population groups by a combination of ecological niche analysis and least-cost path analysis. In the proposed method, niche probability is predicted by MaxEnt, an ecological niche model based on the maximum entropy theory. Location of known archaeological sites and environmental factors derived from palaeoterrain and palaeoclimate models, are input to the model to calculate the niche probability at each spatial pixel and weights of the environmental factors. The inverse of probability score is then used as an index of relative dispersal rate to accumulate the travel cost from a given origin. Based on this cumulative cost surface, least-cost paths from the origin to given destinations are visualised. This method was applied to the Initial Upper Palaeolithic population group (probably of modern humans) in Eurasia. The model identified three migration routes from the Levant to (1) Central Europe via Anatolia and Eastern Europe, (2) the Russian steppe via Caucasus Mountains, and (3) the Altai region via the southern coastal Iran and Afghanistan.

Were tanged points mechanically delivered armatures? Functional and morphometric analyses of tanged points from an Upper Paleolithic site at Jingeuneul, Korea

A total of 99 tanged points have been unearthed from the Jingeuneul site in Jinan-gun, Korea. The exceptionally large number of tanged points suggests a specific site function at this location. Even though the tanged point is one of the representative tool types for Korean Upper Paleolithic assemblages, the function of this tool is not well known because no systematic use-wear analyses have yet been undertaken. Here, we conduct a use-wear analysis of 95 tanged points from the Jingeuneul site. The use-wear analysis reveals that a considerable number of the tanged points show diagnostic impact fractures (DIFs). Because a large number of the tanged points appear to have been used as hunting weapons, a morphometric analysis is also undertaken to examine the potential projectile capability of the tanged points with DIFs. The large dimension of the DIFs and the complex fracture pattern of the tanged points, as well as the small morphometric values of the tip cross-sectional area, tip cross-sectional perimeter, and neck width of the tanged points, all suggest that the tanged points from the Jingeuneul site were mechanically propelled using a spear-thrower or a bow.