The Pleistocene Later Stone Age south of the Limpopo River

The earliest Later Stone Age (LSA) industries from southern Africa are microlithic and unstandardized and include the bipolar technique. The dating of these industries is controversial and the earliest microlithic industry is said to occur at Border Cave at about 39,000 B.P. By 18,000 B.P. a bladelet tradition was established and this was replaced in many parts of southern Africa, at about 12,000 B.P., by a widespread and prolific nonmicrolithic industry, characterized by side-struck flakes. The late Pleistocene environment was colder than present, with particularly harsh conditions during the Last Glacial Maximum (LGM), between about 20,000 and 18,000 B.P. Populations may have been isolated because archaeological visibility is low during the LGM and decreases further after the LGM. After 13,000 B.P. there is a dramatic increase in sites and this implies that there may have been widespread colonization of territory previously unoccupied for tens of thousands of years. By the end of the late Pleistocene there was a change in hunting patterns, in parts of southern Africa, from an emphasis on the capture of large, gregarious grazers to an emphasis on small, solitary browsers. Social complexity increased during the late Pleistocene, and by 12,000 B.P. it seems possible that Stone Age people were observing some social practices recorded historically among Bushmen (San).     

The Virgin Anasazi,far western Puebloans

In the American Southwest, the Virgin Anasazi region included the western part of the Colorado Plateaus and the river valleys of the adjoining Mojave Desert in Utah, Nevada, and Arizona. This occupation spanned the Puebloan periods from Basketmaker II to Early Pueblo III, roughly A.D. 1 to A.D. 1200. Virgin Anasazi subsistence combined cultivation with hunting and gathering. Current research is unveiling a prehistoric society with flexible food procurement strategies and group organization. They underwent a version of the pit house-to-pueblo transition familiar from the Kayenta and northern San Juan areas. Both intra- and interregional exchange seems to have peaked in Late Pueblo II times and then fallen off prior to the end of their culture history. Face-to-face communities remained small, even into the late 1100s, when other Anasazi areas saw the beginnings of aggregation. Their fate, early in the widespread abandonment of the northern Southwest, remains to be understood.     

Holocene prehistory of the northernmost north Pacific

We examine evidence for Holocene contact between Asia and North America across what is now the Bering Strait, emphasizing maritime adaptation. After 10,000 B.P. residual influence of the Siberian Paleolithic is clear, and derivative Americans were moving southward along the open Pacific coast and settling in the eastern Aleutian Islands. By 6000 B.P. maritime adaptation is evident in the Kodiak Island region, and expansion westward brought colonization of the entire Aleutian chain of islands before 3000 B.P. In Asia there was marine subsistence on Hokkaido by 6000 B.P, but in the lower Amur River region, the southern and northern regions of the Okhotsk Sea, the coast of Kamchatka, and the Chukchi Peninsula no major maritime interest can be dated until after 2700 or even 2500 B.P In north Alaska, the mainland was cut off from Siberia by 6000 B.P with the rise of postglacial seas, but contact was reestablished 5000 B.P at the cultural level of the nonmaritime Siberian Neolithic. Pronounced marine orientation appears intrusively in north Alaska somewhat before 3000 B.P, when the only known source for the technology was the region extending from the Gulf of Alaska through the Aleutian Islands. Thereafter developed the maritime culture of the historic Eskimo people.     

Prehistoric Human Impacts to Marine Mollusks and Intertidal Ecosystems in the Pacific Islands

From long-term stratigraphic records in Pacific Island archaeological sites, researchers have documented alterations to molluskan species richness and abundance, decreases or increases in mollusk shell size and, in rare cases, human foraging may have contributed to the extirpation of mollusk taxa. Mollusks perform critical ecosystem functions in tropical intertidal environments, including improving water quality through filtration, regulating algal cover, and increasing habitat and substratum complexity through ecosystem engineering. These critical ecosystem functions can be negatively affected by human foraging, possibly contributing to decreased resilience of coral reefs to climatic alterations. We review modern ecological research on human impacts to mollusks and intertidal ecosystems that illustrates the mechanisms and effects of human foraging. We then examine centuries to millennial scale archaeological records from the Pacific Islands to understand long-term, time-averaged trends in human impacts to intertidal ecosystems.     

Effect of stereotomy on the lower bound value of minimum thickness of semi-circular masonry arches

Constructing structural systems with the minimal required cross section of its members was a strong motivation for progress whole along the history of building. This article investigates the effect of stereotomy on the minimum thickness value of a semi-circular arch made of masonry: a material with negligible tensile strength. The arch is modeled with its center line to which the loading is assigned according to arch length. Here, instead of some scalar parameters such as the rupture angle and the location of the middle hinge on the intrados, the geometry of the stereotomy is associated with a continuous function. Stereotomy-related constraints are introduced to keep the results feasible from an engineering point of view, and it is also demonstrated that they are essential for a well-posed constrained optimization problem. The necessary condition for a non-vanishing lower bound of minimum thickness values is derived analytically considering the assumptions of limit state analysis, infinite friction, and a no-tension material model. The lower bound thickness to radius ratio (t/R) is found to be t/R = 0.0819. A numerical method is introduced to demonstrate the existence of a valid stereotomy at the lower bound. Multiple admissible stereotomy patterns are presented at various minimum thickness values (higher than the lower bound) to demonstrate that suitable stereotomy for a fixed (t/R) ratio is far not unique—in general even the location of the middle hinge and the rupture angle might vary.     

Bone stable isotope studies in archaeology

Stable isotope ratios of carbon and nitrogen in bone have become increasingly frequent inclusions in archaeological reports over the past few decades. The majority of such studies has been done in North America, where the use of marine foods and the introduction of maize have been monitored. Similar questions have been addressed in Mesoamerica and South America. In Europe, stable isotope ratios have documented the shift from marine fishing and gathering to agriculture in coastal areas and the introduction of millet in parts of eastern and southern Europe. Much work remains to be done in Asia, where millet replaced early C3 plant foods and, in turn, was replaced by rice. In Africa marine adaptations, freshwater fishing, agriculture, and pastoralism all yield diagnostic isotopic signatures. We review these studies, discuss areas requiring further study, and close with discussions of areas promising interesting future developments.     

The Natufian: Settlement variability and economic adaptations in the Levant at the end of the Pleistocene

The relationship between current interpretations of Natufian settlement and subsistence and available archaeological data are examined in light of recent research, particularly in Jordan. Regional variability in adaptive strategies is discernible, particularly between forest and coastal sites versus steppe and desert sites. Greater evidence of plant processing and more intensive occupation characterize settlement in the former, although year-round occupation has yet to be conclusively demonstrated. Patterned variability also exists between two classes of steppe and desert area settlements. One set of steppe and desert sites is characterized by a broad range of activities and moderate settlement permanence and activity intensity, while less permanent occupation and more specialized activities focused primarily on hunting typify the other set of sites. Evidence for food production in the Natufian is examined and, although the domestication process may have begun, no morphological evidence exists for the domestication of plants or herd animals. Finally, worthwhile areas for future research are outlined.     

Identifying food provenience using Sr/Ca ratio in human enamel

The strontium (Sr) concentration in bioapatite of human bone and teeth reflects the Sr concentration in food that is differentiated by two major factors: an abundance of Sr in local soils and the biopurification effect along the trophic levels. Eastern Syria is an area with a relatively high concentration of Sr within the Euphrates valley and a low concentration of Sr beyond the valley. For this reason, the strontium/calcium (Sr/Ca) ratio in human enamel retrieved from skeletons buried in cemeteries within the Euphrates valley may be used as a proxy for food provenience in a local population. A sample of human teeth (N = 72) from Tell Ashara and Tell Masaikh was divided into seven temporal subsets covering periods between c.2200 bce and the early 20th century ce . A significant difference in Sr/Ca values between temporal subsets is observed. The Sr/Ca values in later subsets are negatively correlated with δ¹³C values, indicating the wider exploitation of steppe areas outside the valley with more wild C4 grasses and a low Sr concentration. For periods with lower Sr/Ca values (c.2200–1900 bce and 19th–20th centuries ce ) there is additional textual and isotopic evidence for food transportation from outside the river valley, supporting the interpretation of Sr/Ca values as a proxy for food provenience in this specific area.     

当代中国城市低保制度的演进及反思

当代中国城市低保制度从1993年起,经历了初创及试点、正式确立及全面实施、应保尽保、规范管理和全面法制化五个阶段。随着该制度的日益完善和操作程序的不断规范,城市低保制度开创了一种既符合我国国情,又与国际接轨的社会救助新模式,对保障城市困难群众的基本生活、维护城市社会稳定、推动经济体制改革都起到了重大促进作用。城市低保工作呈现出保障人数大体稳定、财政投入逐年增加、保障水平不断提高的态势。该制度面临的困难和问题需要结合国际扶贫的新模式和当前我国的低保工作的实践进行完善和创新。     

河南邓州八里岗遗址出土植物遗存分析

植物遗存的分析显示,八里岗遗址前仰韶时期的植物性食物资源主要是水稻和橡子等,经济方式上农业与采集并存。自仰韶时期开始,则一直保持了稻粟黍的作物组合,但各种作物的比例在不同时期存在一定的变化,同时这种变化与该遗址的考古学文化变迁是相符的,从农业经济的角度体现了南北方文化的消长过程。稻属穗轴形态的分析则表明该遗址驯化穗轴自前仰韶时期开始一直保持了很高的比例,驯化过程可能很早就已完成。此外,从对杂草遗存的分析结果来看,该遗址整个新石器时代的作物加工模式或许没有发生太大的变化,作物加工的大部分步骤都是在遗址上进行的。